FIELD CROPa -IN- SOUTH AFRICA BY LEPPAN AND BQSMAN SOUTH AFRICAN AGHICULTUlAi SERIES, Md. S CENTRAL NEWS AGENCV. LTP. SOUTH hfmCh % §. p. -BtU ^tbrarg vi ^orl{| Carolina ^tate College S00493195 V Date Due -EB 5 '4' i ' P&!k um^ UfC 1 U 1^ r # ,. ,. .. L. B. Cat. No. 1137 FIELD CROPS IN SOUTH AFRICA South African Agricultural Series — No. 1 ARGUS 1 printed by the Argus Printing and Publishing Co.. Ltd.. Johannesburg. South African Agricultural Series — No. 1 FIELD CROPS IN SOUTH AFRICA H. D. LEPPAN, B.Sc.A. (professor in agronomy, TRANSVAAL UNIVERSITY COLLEGE, UNIVERSITY OF SOUTH AFRICA) AND G. J. BOSMAN, B.Sc.A. ^TECHNICAL ASSISTANT, UNION DEPARTMENT OF AGRICULTURE.) WITH FORTY-TWO ILLUSTRATIONS 21/- PRICE V I /- NEXT SOUTH AFRICA CENTRAL NEWS AGENCY, ITMITED, 1923 s^U "' ^' ^^«^e Col/ege PREFACE South African agriculture, by reason of extremely diversified climatic conditions and peculiar economic factors, presents a great variety of problems to the beginner, and especially to the settler, who is unfamiliar with local conditions. It is unfor- tunate, too, that the supply of local agricultural literature is very meagre and often difficult to obtain. The aim of the authors has been to give a concise account of the cultivation of crops in the Union, in the hope that it will be of service to our farmers and prospective farmers. It has been written not only for these, but to assist students and teachers at the various institutions where agriculture is taught. To some it may not be sufficiently technical, to others it may appear too much so. The former will have to supplement their reading by the use of more specialised works, a selected list of which is given below ; the latter are advised to pass over technical descriptions, and it is hoped that sufficient practical information will be found to be useful. No doubt a great deal that is contained herein will need to be revised as more data are accumulated ; owing to lack of con- clusive data, much is necessarily speculative. It is, therefore, the earnest wish of the authors that criticisms and additional information will be sent to them, so that if a new edition is called for, it may benefit by such criticism and information. A great many publications have been consulted and duly acknowledged. In some cases, however, there may have been unwitting omissions, and here the authors crave the indulgence of those whose publications may have been consulted without due acknowledgment. This opportunity is taken to thank Dr. J. C. Eoss for reading the manuscript of certain chapters, and for his valuable suggestions in regard to Chapters III. and IV. We are especially indebted to him for the account given under " Brak Soils." The authors also wish to express their appreciation of Mr. H. W. Taylor's kindness in allowing them a free use of his articles on tobacco. -5, f-^mtr^* iij The list of text-books given below may prove useful to those wanting an elucidation of points which have not been given in sufficient detail, or, to those requiring further informa- tion : Botany of Crop Plants ... Agricultural Botany Breeding Crop Plants ... Genetics in Pielation to Agriculture ... Fungous Diseases of Plants Plant Genetics ... ... Soils, Their Preparation ^r Management Soils Soil Physics and Management The Feeding of Crops and Stock Principles of Irrigation Practice Soil FertilJtv t't Permanent Agriculture ]\obbins. Percival. Hays & Gerber. Babcock &: Clausen. Duggar. Coulter. Lyon, Fippin &: Buckman. Hilgard. Mosier d' Gustafson. Hall. Widstoe. Hopkins. HUBERT D. LEPPAN. G. J. BOSMAN. Pretoria, March, 1923. I'lUUA'lA. On |)a-i' 18 (No. S) lUi.^ic .S7nf/ .-—Containing about 8 lo lit* per cent, iiitroo-en. This sliould read 8 to 20 per cent. l?lioiiphoricAckL On page 1 10, line 22, reading M. jaicata the seed is earned in sp'iral pods. This sliould read M. Sativa the Beed is (.aiiie.i in spiral pods. CONTENTS Page. CHAPTEE I Historical and General Survey 1 CHAPTEE II Agro-geographical Conditions in Eelation to Crop Distri- bution in South Africa 7 CHAPTEE HI Soil-Management : Tillage, Irrigation, Drainage and Brak Soils 17 CHAPTEE IV Soil Management (Continued) : Fertilizer Practice, Green-manuring and Weed Control 44 CHAPTEE V The Eotation of Crops 62 THE PRINCIPAL SUMMER CROPS CHAPTEE VI Maize 73 CHAPTEE VII Sorghums 108 CHAPTEE VIII Potatoes 122 CHAPTEE IX Lucerne 139 CHAPTEE X Cow Peas, Soy Beans and Peanuts 152 vii CHAPTEK XI Cotton 167 CHAPTEK XII Tobacco 184 CHAPTER XIII Sugar Cane 216 THE PRINCIPAL WINTER CROPS CHAPTER XIV Wheat 226 CHAPTER XV Oats ....'. 259 CHAPTER XVI Barley and Rye 270 MISCELLANEOUS CHAPTER XVII Grasses and Millets 281 CHAPTER XVIII Root and Allied Crops 301 CHAPTER XIX Flax , Buckwheat , Sunflowers and Pumpkins 311 CHAPTER XX Minor Crops 323 CHAPTER XXI Dry-land Farming 340 Index 355 vui LIST OP^ ILLUSTRATIONS. To FACE Plate. Page I.— Land in Good Tilth 88 II. — Teosinte (Euchlaena Mexicana) ; Species of Maize 88 III. — Ear of Iowa Silvei' Mine; Ear of Maize, showing Poor Fertilization 88 IV. — Maize with Cowpeas grown between the rows ; Maize with Cowpeas grown in the row 88 V. — Silos, showing Cutter and Blower 120 VI. — Types of Sorghums 120 VII.— Heads of Kaffir-Corn 120 VIII.— Plant of Feterita 120 IX. — Potatoes of Good Quality and Poor Quality; Amount of Internal Medulla and Cortex 136 X. — Potatoes in Ridges being Cultivated; Lucerne Plant 136 XI. — Cowpea Roots, showing Nodules; Soybeans 136 XII. — iCowpeas in Centre with Soybeans on Left and Right ; Green-Seeded Bancroft Cotton 136 XIII.— Peanut Plant, Runner Type; Peanut Plant of Erect Type 168 XIV. — Picking Cotton; Tobacco Seed-Beds 168 XV. — Field of Turkish Tobacco ; Joiner Tobacco, showing the Inflorescences of Selected Plants covered with Manilla Bags 168 XVI.— Conveying Virginia Tobacco (Whole Plant Method) from the Field; Turkish Tobacco on Curing Racks 168 XVII.— A Field of Algerian Oats; Rye Kernels, Soft Wheat Kernels 264 XVIII.— Uba Sugar-Cane 264 XIX.— Oat Kernels, Cross-Section of Oat Seed; Wild Oats, Common Oats 264 XX. — Heads of Various Varieties of Barley 264 XXI. — Kernel of Awned, Two-Rowed Barley; Kernels of Hooded Six-Rowed Barley 280 XXII. — Barley Kernels with Hull Removed : Good Malting Barley, Poor Malting Barley 280 XXIII.— Millets 280 XXIV. — Mangels; Sugar Beets 280 XXV. — Sections of Young Mangel, showing Rings of Vascular Bundles 328 XXVI.— Plot of Sunflowers 328 XXVII. — Mung Bean (Phaseolus Aureus) 328 XXVIII.— Old Man Saltbush (Atriplex Nummularia) ; Spineless Cactus 328 FIELD CROPS IN SOUTH AFRICA CHAPTER I HISTORICAL AND GENERAL SURVEY Field Husbandry, Agronomy and Phytotechny are synonyms used to denote that branch of agriculture which treats of the theory and the practice of the production of crops. The Chinese saying, " Public prosperity is like a tree ; agriculture is its roots ; industry and commerce are its branches and leaves. If the root suffers the leaves fall, the branches break and the tree dies," is as true to-day as it was centuries ago. On account of its importance to the welfare of humanity a brief review of the development of field husbandry and its present status is not unwarranted. Early Evolution. — Excepting the very recently developed countries , the embryonic stage of agriculture has presented a development along very similar lines in the various parts of the world. Even the pioneer farming of to-day, as found in parts of Africa, South America and elsewhere, has certain features showing very little advance over that of twenty centuries ago. During the early history of a tribe and of the compara- tively younger pioneer communities, ^he growing of food crops on cultivated J[and was seldom the_&stdevelbpment^^^^^^ Allowed only when' t~be~ returns 7rom hunting," filing, and the ga;t^herrng"of wildTruits and roo^s were no longer sufficiently stabte or plentiful to supply the needs of a growing population. In most cases the domestication and herding of animals with- out the cultivation of crops followed this phase; in some, e.g., the Eed Indian, who, before the advent of Europeans had domesticated onlv the turkev and the dog, the agricultural 2 CHAPTER I stage was reached without passing through the pastoral stage. Some nomadic tribes continued for many centuries as pasto- rahsts only. As populations grew, and for reasons political, economic and otherwise, became more restricted to certain localities, the purely pastoral sta^e gave way to a combmed^ricultural and f;3:sf(5rarpliase, and animaTliusbandry slowly merged with f5^d liQsbandfT:~"The cultivation of crops was necessary to supplement the natural "sTrpplie^,—- particularly during those seasons of the year when the l^ittcr were unobtainable, and also to support the domesticated animals during the periods when the natural pasturage was inadequate. Directed by experience, a remarkable choice of animals and crops was effected in the earliest times, since all the domesticated animals and nearly all the important crops of to-day have been employed in farming since the beginning of recorded history. Wheat and barley seed have been found in the remains of the Stone Age ; petrified maize ears have been found in Peru, together with evidences of ancient human activities; and so forth. Considering the vast accumulation of botanical knowledge of the last two centuries, it is astound- ing that of the important cultivated crops of to-day, practi- cally none has been discovered during this period. A few new fodder plants have been found, it is true; but in most cases their superior utility is still to be proved. The great civilisations based upon agriculture began in three regions which had no inter-communication — viz., China, where rice, the sweet potato, wheat, sorghum and millet (Setaris italica) were grown ; the south-west of Asia (with Egypt) growing the bean, lucerne, pea and water-melon; and inter-tropical America, where the potato, maize and tobacco were cultivated.^ While some of these and other cro))s were originally grown in other parts, it is generally held that the regions mentioned were really the birthplaces of great civilisations established on the products of cultivation. Here it might 'be mentioned that in no case do the pro- genitors of either domesticated animals or crop plants, when measured by their utility for men, compare with the strains employed to-day. This is due, of course, to the selection of superior and permanent variations, and in later years partly to ariificial hybridisation. Among the early agricultural writers none excels either Cato or Varro in precision and clear description. A great ' " Origin of Cultivated Plants." — De Candolle. HISTORICAL AND GENERAL SURVEY. 6 many of their observations relate to rural economy — their deductions are amazingly accurate and inaccurate. They attributed a great many diseases and disasters to the influence of certain stars and phases of the moon. It is natural that they should have done so, since, knowing no science, they attributed the inexplicable to the malevolent action of things over which they ha.d no control. On the other hand, the benefits to be derived from land drainage, seed selection, the use of barnyard manure and lime, and the residual elfect of legumes on the soil were recognised by these writers in no uncertain manner. As previously stated, practice in field husbandry has developed along very similar lines all the world over. In most cases the primary stages were characterised by the small variety of crops grown ; the first and most important crop almost invariably being one of the cereals ; the same crop was grown continuously on the same land, with the inevitable result that the productivity declined steadily. Finally, the land was abandoned, and virgin land cultivated in its stead. " This custom of abandoning partly worn out land has been almost universal in the history of all nations and their agriculture." The Early Use of the Bare Fallow." — " Along with such agricultural experience as taught man that cultivated lands continuously growing cereals soon lost their producing power came the knowledge that idle lands had to recuperate their power to yield good crops. The experience of the farmers of many nations, in many climates, showed that idle, aban- doned land would regain productivity. In man's early dis- covery of this principle we find the origin of the practice of ' bare fallowing.' As land became scarcer, and as agriculture increased in importance, the bare fallow became a systematic feature of agriculture. Instead of working land to a. condition of unproductivity and then abandoning it to nature, the farmer cropped the land continuously, with regular fallow periods every second or third year. " Modern agricultural science reveals the fact that, while the 'bare fallow acts as a temporary stimulus to soil produc- tivity, it is a practice that serves to hasten the ultimate im- poverishment of a soil area. It is now used less often, and then only to destroy weeds and, in some regions, to conserve moisture." To-day the green-manure fallow has taken its place among progressive farmers. 2 " Field Management and Crop Rotation." — Parker. 4 CHAPTER I The Use of Legumes. — As previously stated, the Komans were aware of the beneficial residual effect of these plants on the land, and their use has been since then increasingly advocated. Towards the end of last century bacteriologists discovered the relationship that exists between legumes and nitrogen-gathering bacteria. This definite knowledge gave a decided impetus to the use of legumes, and to-day the greater number of rotations practised in all countries contain one or more of these plants. Rotations. — In a sense Varro had advocated rotative ^ cropping , and it is known that in a very intensive manner 'fhe Chinese have practised crop rotations for centuries. Systematic cro^jo rotations, as understood to-day, were not common until the beginning of the eighteenth century, when Lord Townshend introduced the famous Norfolk rotation. The subject of rotation is dealt with more fully in a later chapter. Manuring. — The beneficial effect of the use of animal excreta on the soil, and even the superiority of that of certain animals over others, was known to the ancients, and the liming of soils had been practised in the days of Varro. How- ever, it was not until after de Saussure, about 1805, had shown the mineral character of plant-food that the use of artificial manures was practised. Their use has grown rapidly in all parts of the world and they are utilised in the cropping systems of all countries to-day. Apart from the points above- mentioned, the remarkable advance in field husbandry of the last two centuries is due to a great many factors, chief among' whicli are the following : — (1) The discovery of the gaseous assimilation by plants. (2) The use of improved farm machinery. In 1701, Jethro TuU invented the seed-drill, to be followed afterwards by others, with improved ploughs, and, later, mowing and thresh- ing machines. (3) The application of genetic laws to the improvement of plants. (4) Economic entomologists and plant pathologists came forward with remedial measures against insect pests and plant diseases. (5) The establishment of technical agricultural institutions. Agronomy and Animal Husbandry. — Histoi-y shows that the productivity of the soil is best maintained, and often increased, in those parts where the rearing of animals is an essential feature of the farming practised; more particularly, of course, where concentrates are fed and the manure returned HISTORICAL AND GENERAL SURVEY. 5 to the soil. Again, a study of the development of agriculbufe shows conclusively that, as a system of permanent farming, the practice of utilising the land for pasturage and at the same time feeding the greater part of the crops grown and '-eturniag the manure to the soil, has characterised those parts where agriculture is stable and prosperous. Moreover, in a given region, the possibilities for animal production are ultima t'ly dependent upon the potentialities o£ that region for crop production. Development in South Africa. — In much the same way as in other countries, field husbandry practice in South Africa was based on a single cropping system. Wheat was, and still is, the principal crop in the Western Pro'^ltoce. In a short while the introduction of the bare fallow (braaking) was found necessary, and in that area it is only of _ recent years that the necessity JfliL.£rop rotations, manuring and_Jbe rearing of stock as an integral part of profitable and permanent larining tave been recQRQJsed. *" It is to be expected that in a new country crops w^ere grown in parts totally unsuited to their profitable cultivation ; e.g., wheat in the Eastern Province and Natal. Experience has demarcated the cultivation of the various crops into distinct zones; so that to-day we have a maize belt, definite wheat areas, a sugar cane belt, and so forth. Until recently South Africa imjported a great deal of ordinary farm produce, such as meat , "Butter ,e^£a_n(J^maize; all 'oT whicTT are to-'Hay' ISeiBg' g:S:porte(r: in the history'oT'any agricurEuraT c6uhT,fyli,' ^IBrie coines" when agricultural development progresses from petty local trade into world commerce. This stage may be said to have commenced in South Africa in 1907, when maize was first exported in quantity, and to-day the increasing value of her exported agricultural products is fast decreasing the disparity that existed between her exports from mining and agriculture . The total production . dir.eatly i rom the soil (apart from the aniinal industry) approximates in value that of min- ing. However, bearing in~miTrd'"Oiir UgilculHral resources, Sr~si3rvey of the agricultural production of other countries, more favoured in regard to the possibilities of agriculture, forces one to the conclusion that South Africa will never compete seriously in the value of her agricultural production with countries like Canada or Argentine. The remarkable change in field husbandry that has taken place during the last two decades is due to the introduction 0 CHAPTER I of technical men, the establishment of experimental stations and schools, and the importation by the Department of Agri- culture of improved strains of crops. The Scope of Agronomy. — While field husbandry in the broadest sense may be held to include horticulture, with its sub-divisions of pomology, olericulture, floriculture, and forestry, nevertheless it is customary to limit the study to the following crops : — (a) Grain crops — e.g.. Wheat, rye, oats, barley, buck- wheat and maize. (b) Forage and fodder crops — e.g.. Lucerne and the various grasses. (c) Eoot and allied crops — e.g.. Mangels, turnips and potatoes. (d) Fibre crops — e.g., Flax, sisal and cotton. (e) Sugar crops — e.g., Sugar cane and sugar beets. (f) Drug crops — e.g.. Tobacco and tea. The study of agronomy is too comprehensive to be fully dealt with in 'a small treatise of this nature, and where more detailed data are required the reader must consult the various texts. It involves, broadly speaking, four main avenues for investigation. (1) Edaphies. — This includes a study of the chemistry, physics and biology of the soil in relation to plant culture. (2) Phenology. — Here the effect of climate in relation to growth is studied, e.g., temperature, humidity and move- ments of air, duration of light, etc. (3) Carpoies. — Which involves a knowledge of plants as' crop plants, and embraces questions dealing with adaptation (bionomics), plant breeding (genetics), cultural methods, and the control of pests (plant pathology and economic ento- mology). (4) Rural Econaonics. — A study of rural communities, their organisations and problems. Faculties of agriculture and schools of agriculture are now fully established in the Union, in which agricultural subjects form part of the curricula. CHAPTEE II AGRO-GEOGRAPHICAL CONDITIONS IN RELATION TO CROP DISTRIBUTION IN SOUTH AFRICA Agronomic production is, of course, directly correlated with the natural factors of production. It is necessary, therefore, to discuss these somewhat in detail : Eainfall. — Too often the capacity of a region to produce crops is estimated on the average annual precipitation. That this, especially in South Africa, is misleading will be shown in the following discussion, in which the very important modi- fying influence of yearly fluctuation, seasonal distribution, character, evaporation and run-off of rainfall are taken into account. The average annual rainfall on the east coast of England is only 26 inches ; in Lincolnshire and Essex the averages are as low as 18 and 20 inches respectively, yet the lack of moisture is never so acute there as in parts of South Africa where the average is nearly 30 inches per annum. The reasons for this are as follow : — (1) In this part of England the seasonal rainfall is more evenly distributed throughout the year ; 20 per cent, of rain falls in spring, 23 per cent, in summer, 31 per cent, in autumn and 26 per cent, in winter. In the Transvaal approximately 90 per cent, falls in the six hottest months. (2) The evaporation from a free water surface near London is only 20.6 inches per annum, whereas in South Africa it ranges from 65 inches to 75 inches. (3) The rain is of a soft, misty character in England, while in South Africa it is precipitated generally in heavy torrential downpours. Consequently the loss from run- 8 CHAPTER II off, while negligible in England, becomes extraordinarily severe in South Africa. Instances are by no means uncommon in the Karroo, where the precipitation during 48 hours has equalled the average annual rainfall for that part. Local Annual Fluctuations. — These should be noted most carefully, particularly in those parts of the country where the rainfall is below 30 inches per annum. The following examples will serve to emphasise the importance of this point : — Average 13.31 ins. Average 18.80 ins. Average 23.69 ins. Griquatown, Bethulie, Zeerust, C.P. O.F.S. Transvaal. Year. Total for year. Total for year. Total for year. 1901 14.39 ins. — — . 1902 12.91 ,, — — 1903 5.73 ,, — — 1904 10.07 „ — 24.35 1905 8.92 „ — 17.26 1906 11.72 „ — 27.37 1907 17.03 „ — 28.87 1908 6.06 ,, 8.65 16.04 1909 18.54 ,, 29.24 39.79 1910 9.23 „ 14.36 18.73 1911 15.15 „ 22.67 28.73 1912 5.66 ,, 11.76 16.71 1913 15.18 „ 16.33 20.01 Presuming these to be areas where crop production is general, which they doubtless would have been were the fluc- tuations more infrequent, and the rain less torrential, then an examination of these figures would tend to show that the farmer at Griquatown growing a crop which might be expected to give fair yields on 13.31 inches per annum would have crop failures during the years 1903, 1905, 1908, 1910 and 1913, while during the three years 1902, 1904 and 1906 he would have three veiy indifferent crops. Thus out of the thirteen years he would have five normal yields, five total failures and three probably poor crops. Out of the six years at Bethulie, the grower, relying on an average of 18"80 ins. per annum, would have two normal crops, three failures and an indifferent one. At Zeerust, relying on a rainfall of 23"69 ins., he would have five failures and five normal crops. A summary of this nature, while very theoretical, shows how often the expectation of an average annual precipitation might lead to disappointment. AGRO-GEOGRAPHICAL CONDITIONS IN SOUTH AFRICA. In some areas, fortunately, the fluctuations are less, and in these crop-growing is more assured, e.g. : — Bethal, Transvaal (average 30.39 ins.). Year. Inches. 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 '26.69 35.3 22.6 39.81 30.36 33.83 26.44 22.84 42.60 32.88 Bethal is situated in one of the largest and most certain maize and potato producing districts in the Union. That it is so is attributable not only to the high average rainfall, but to the small yearly fluctuation. In the period taken, only once (in 1908) was the precipitation as low as 74 per cent, of the average annual rainfall, whereas at Griquatown, Bethulie and Zeerust, during several of the bad years, the rainfall was between 42 and 45 per cent, of the average annual rainfall. In parts of Natal, too much rain occurs in some years ;, resulting in crop failures, because of the water-logged condition of the soil in those seasons. Evaporation, Character, Distribution and Eun-off. — In considering the dissipation of the rainfall, these factors are intimately connected. Generally speaking, in a country like South Africa, where the evaporation is usually three to four times as large as the precipitation, a precipitation of half an inch or less is of very doubtful utility, since the penetration of the rain is so small that the evaporation of the whole would take place probably before capillary connection with the lower soil moisture has been accomplished, and before succeeding showers have taken the penetration to an effective depth. Over the greater part of South Africa 20 to 30 per cent, of the annual rainfall occurs in light showers of this nature, which on the whole is of very little advantage in crop production. With the exception of a few localities, to be mentioned later, the rainfall in the Union is mainly of a pelting, torrential character which soon deflocculates the surface soil particles into a relatively impervious layer. The air is imprisoned in the interstices of 10 CHAPTER II the soil, consequently the water is admitted very tardily and the run-off becomes very heavy. The amount, of run-off depends largely, of course, on the topography of the ground, whether mountainous or otherwise, the nature of the soil and the date of the occurrence of the last rains. If the region is mountainous and rocky, the run-off might very well be as high as 80 per cent., and on heavy clay soils it will naturally be much higher than on porous, sandy soil. It is not an exaggera- tion to say that under most South African conditions, when measured agronomically, the run-off varies from about 20 per cent, to 80 per cent, of the rainfall occurring in heavy showers, and is seldom as low as 5 per cent. The causes are now sufficiently clear of the low crop pro- ductivity in South Africa as compared with parts of England or countries similarly favoured, notwithstanding a superior total rainfall. Seasonal and Annual Distribution Throughout South x\frica. — The average annual rainfall in South Africa varies from about 50 inches on the Natal coast to less than 2 inches at Luderitzbucht, on the coast of the South- West Protectorate. With the exception of the south coast and the south-west corner of the Cape Province, the rainfall decreases from east to west, and naturally the agriculture changes in correlation. At Wemmer's Hoek and Berg Eivcr Hoek, in the south- western Cape, the rainfall is as high as 200 inches per annum, and in some limited localities in the north-eastern Transvaal and near Maritzburg, in Natal, it is nearly 70 inches per annum. Over one-half of the territory comprised in the Union receives a rainfall varying from 20 inches to less than 5 inches per annum. Less than a quarter receives more than 24 inches, sufficient, in effect, for grain crops to be reasonably productive and profitable without the aid of irrigation. Nearly the whole of this latter territory lies in the eastern portion of South Africa, in which about 80 per cent, of the precipitation falls during the summer months. The whole of Natal, Basutoland, approximately one-third of the Transvaal and Orange Free State, and less than one- tenth of the Cape Province, Griqualand East, Pondoland and a few isolated areas receive about 25 inches of rainfall during the year. The Union, generally speaking, may be divided into three distinct areas as far as the seasonal distribution is concerned, viz. : (1) The winter rainfall area, which includes the Western AGRO-GEOGRAPHICAL CONDITIONS IN SOUTH AFRICA. 11 Province as far as Cape Agulhas and in which the precipitation is of a less torrential character than in the remaining areas. Here the rainfall is more effective, since the loss from evapora- tion is less because of the relative low temperatm'es found in winter. (2) The all-the-year-round area, which includes the coastal section from Agulhas to Port Alfred. (3) The summer rainfall area, which includes the coastal parts east of Port Alfred as well as the plateaux inland. The agriculture prac- tised in these three areas is necessarily directly related to the seasonal rainfall. ' In (1) winter crops, in (2) summer and winter crops — though neither are very assured because of the torrential character of the rainfall — and in (3) summer crops are those which are most successful. Based on the average annual precipitation in the summer rainfall area, crops without irrigation are roughly successful as follows : — Rainfall. Crops. 45 inches and above. Sugar-cane. 24-45 inches. Practically all common summer field crops. 20-24 inches. Peanuts, cotton, sorghums, millets and sunflowers. 15-20 inches. Fodder crops such as Sudan grass and millets. 5-15 inches. Saltbushes, prickly pear, Mexican aloe, Prosopis juliflora, etc., i.e., perennial fodder trees and shrubs. The cultivation of crops is rapidly becoming demarcated and characterised for the different rainfall zones, and doubtless will become more marked as experience of our conditions in- creases. Kunning from east to west up to the 24-inch isoheyt (isoheyt, an imaginary line connecting places which have an equal annual rainfall), summer grain growing is reasonably secure and the favourable precipitation has permitted the in- auguration of more intensive farming. Thus on the high veld of the north-eastern Free State and the Transvaal, in East Griqualand and Natal, besides crop cultivation, dairy, pig, poultry and fruit farming are increasing markedly. Between the isoheyts of 20 and 24 inches we find grain farming as the chief feature of agronomy is fast being sup- planted by the cultivation of the more drought resistant cereals, i.e., flint maize, grain sorghums and fodder crops. 12 CHAPTER II West of the •20-inch isoheyt farmers are wisely paying more attention to fodder crops, except on irrigated land, where the winter cereals are still commonly grown. Even on this irri- gated land there is evidence that lucerne will take the place of wheat and oats where soil conditions allow. A number are also recognising the necessity of growing fodder trees and shrubs, such as the saltbushes and spineless cactus, where climatic conditions are too uncongenial even for the drought- resistant fodder crops, e.g., millets, Sudan grass, etc. In the south-west Cape, where the rainfall is a wintry one and fairly high, the winter cereals, vetches, field peas and other winter crops are being grown. It is likely that in this region dairy farming will become a more prominent feature , as already the poor sandy soils are fast becoming unproductive, owing to the policy of growing grain for sale, instead of growing grain and fodder for stock on the farms. The latter policy will con- serve the plant food, in that the manure of the animals will be applied to the lands. Where the grain is sold, naturally the land is severely drained of plant food, since the valuable ele- ments in the grain are not returned to the fields from which the crops are taken. In the south-eastern Cape, where the rainfall is a constant one, but for the greater part insufficient and too uncertain for summer or winter crops without irrigation, farmers are giving their attention more to the production of fodders than cereals. On irrigated land in the Union both summer and winter crops are grown, and among the more progressive farmers the tendency is to grow fodder crops, if possible lucerne. While the possibilities for successful irrigation in the Union, especially in the lowveld, are undoubtedly immense, at the same time the pitfalls are numerous, and, before embarking upon this type of agriculture, the uninitiated should obtain full in- formation in regard to the suitability of soils, alkali and silt. A wise policy is to stimulate individual enterprise rather than spectacular irrigation schemes, on which too much capital is often expended. Hail and Snow. — Hail is of considerable severity in some parts, particularly in the middle districts of Natal, in the south- eastern Transvaal, eastern Free State, and in Kaffraria. While fruit growers are the chief sufferers from hail in the parts men- tioned, it is also a serious factor to the grain grower. In the eastern Free State, where wheat and oats are sometimes exten- sively grown on dry lands, these crops mature in November AGRO-GEOGRAPHICAL CONDITIONS IN SOUTH AFRICA. 13 and December, at a time when not only most susceptible to hail, but also when hailstorms are most prevalent. Snow, unfortunately, is of infrequent occurrence and is usually confined to the mountainous districts, e.g., Basutoland and Barkly East. Length of Growing Season. — This is affected by the days of the commencement of the rainy season, the intervals between killing frosts, the altitude and, of course, the latitude. In some parts the commencement of the rainy season is frequently so late as to delay agricultural operations very con- siderably, and the growing season becomes a short and unsatis- factory one. This is especially the case in central and north- western Transvaal. The modification of the length of the growing season by frosts is often a serious one, more particularly to the horticul- turist, but also to the farmer dependent on summer crops. In the Karroo, at Colonies Plaats, records show that during the period of twenty years there is no month throughout the year in which frosts are not liable to occur. However, in general, the interval between killing frosts is usually sufficiently long not to affect the maturity of most of our commonly grown summer crops. It is in seasons when the commencement of rains is late that frosts are apt to be a very limiting factor. As with the rainfall, it is found that there is a gradual increase in temperature along any parallel from west to east. This is true in a general way, provided the stations chosen to exemplify this are fair distances apart, since there are limita- tions imposed by local circumstances. Almost throughout the whole of South Africa the mean temperature is approximately 62° Fah. However, the mean maximum and the mean minimum temperatures differ widely in the different parts. The mean daily range in temperature for the whole of South Africa is approximately 24.5° Fah. It is interesting to compare these with those occurring in the tropics, e.g., at Colombo, where the daily range is only 11° and the thermometer practically never registers lower than 75° or higher than 86°. The peculiar and marked difference between the conditions on the east and west coasts alluded to has been accounted for by the fact that the warm Mozambique current washes the eastern shores in its southerly course, while the colder Benguela current in its northerly course performs an exactly contrary office for the western shores. The first gradually loses its 14 CHAPTER II warmth, while the second rises in temperature as it approaches the equator. Altitude is also of importance in this connection. The growing season is naturally shorter and the nights often cooler on the inland plateaux than at low altitudes. Thus we find that cowpeas in high altitudes will be found more useful than velvet beans; flint maize better than dent maize, and so on. Latitude naturally also affects the length of growing season, but its effect is not so apparent in the Union, because this is largely offset by the increase in altitude from south to north. Soils of South Africa. — As must be expected from the widely differing geographical formations, the soils from these are very divergent in character and productivity. For example, those derived from the Bokkeveld series, composed of soft sand- stones and shales, are very fertile soils and markedly different from the poor sandy soils formed from the often adjacent Table Mountain sandstone series, composed of highly siliceous rocks which weather into coarse, angular fragments. In general it may be said that the soils of the sub-continent are markedly deficient in phosphates, but moderately well sup- plied with potash and nitrogen. That they usually contain sufficient nitrogen is fortunate, as the application of artificial nitrogenous fertilisers is an expensive item in countries not favourably situated in regard to supply. It is impossible to deal with the subject of South African soils in detail. However, certain areas have predominating types, and these are briefly given : — (1) The South- West Cape. — The soils of this region are on the whole poor in fertility, of a light, sandy texture, and of low humus content. Loams do occur, but unfortunately the physical condition of these has deteriorated owing to the poor methods of farming practised. (2) South and South-Eastern Coastal Belt. — Fine sandy loams prevail here ; the nitrogen content is usually higher than in those of the south-west Cape, and more lime is found, but phosphates remain low. (3) Namaqualancl. — Chiefly sandy soils, poor in humus and nitrogen, occur. In some cases calcareous soils are found, and a clay soil found in the Calvinia area appears to be well supplied with phosphates. AGRO-GEOGRAPHICAL CONDITIONS IN SOUTH AFRICA. 15 (4) The Karroo. — As a whole these are probably the most fertile in the Union. In some cases, due largely to the aridity of this part, alkali has proved a serious obstacle. Further, the heavy charges of silt carried in the irrigation waters of this part have an injurious effect on crops like lucerne. The Karroo abounds in dolerite, which accounts largely for the fertility of the soils found there. (5) IS! orth-E astern Cape and Griqualand East. — This area is to a great extent the extension of the Karroo area. In the Albert division a red sandy clay is found. Some very fertile soils are found, but in some parts of East Griqualand some extremely infertile soils occur. Throughout the soils are extremely variable in character and fertility. (6) Eastern Orange Free State and Transvaal Highveld. — These soils are somewhat sandy in character, but much superior to the inferior soils of the south-west Cape and Namaqualand. On the whole they are deficient in phosphates. In both the Transvaal and the Orange Free State large tracts of heavy soils sometimes occur, which, because of their undesirable phj^sical characteristics, are generally not well suited for the growth of ordinary crops. (7) Natal. — Natal soils may be divided roughly into three types, viz. : — (a) A compact calcareous clay loam, found in the sweet- veld and in most parts where crops are successful. (b) An open red soil deficient in lime on which crops do badly. (c) Soils of a very ferruginous character of poor physical condition. Aeration and soil moisture movement are poor, resulting in crop failures because of water-logging in wet seasons and drought in dry seasons. (8) Western Orange Free State. — In the south the soils resemble those of the north-eastern Cape ; possibly alkali is more prevalent, and in the north they are of a very sandy character, though fairly productive. Labour. — As compared with North America, farm labour, generally speaking, is plentiful, cheap and at present inefficient. The South African farmer in many areas finds difficulty in obtaining labour because of the higher wages paid by the organ- isations of the big mining companies. In the cotton growing areas, which coincide with the densely populated native areas, labour is plentiful and suffi- ciently efficient for the requirements. Much might be done to 16 CHAPTER II mitigate this inefficiency, as witness the eastern Free State, where the system in vogue, operating through a generation, has produced very satisfactory results. The apathy of the European employer, coupled with the pernicious three months' system of the Transvaal, are the chief factors preventing the same efficiency being attained in other crop producing districts. The three months' system may be well adapted to ranching, but to no other system of farming. Transportation. — Under the poor facilities for transpor- tation, one finds one of the most serious drawbacks to crop pro- duction. This factor, coupled with the sparse population, is mainly the reason why some areas of enormous crop potentiali- ties are relatively undeveloped. Unfortunately, too, South Africa does not possess the inland waterways offering cheap transportation such as are found in a country like Canada. Capital and Kdral Organisation. — On the whole farmers are under-capitalised for the projects undertaken. In most cases the South African farmer invests too much in acquiring his land, probably because he wishes to avail himself of the unearned increment due to the abnormal increase in the price of land found in young countries. They are extremely unorganised, and in consequence the long term, cheap credit required by them is unobtainable, and they therefore farm under disadvantageous conditions with regard to capital when compared with their brothers in, say, Denmark. Disease. -The development of some areas, particularly in the lowveld, has been seriously restricted owing to diseases like malaria in human beings and ngana in animals. Natural Features. — The amount of arable land, owing to the rugged mountainous condition of the country, is very limited in parts like East Griqualand. Indeed, the percentage of valuable arable land in the Union is very much less than many optimists would have us believe. CHAPTER III. SOIL MANAGEMENT— TILLAGE, IRRIGATION, DRAINAGE AND BRAK SOILS TILLAGE. Jethro Tull (1674-1741) made the statement " tillage is manure," his belief being that if soil particles are sufficiently fine they can be absorbed by the plant. Although the reason he gave was incorrect, nevertheless the practice resulting from his belief proved to be substantially correct. Tillage has been defined as " the manipulation of the soil by means of implements so that its structural relation- ships may be improved for crop growth." It includes the use of all those implements that are employed to stir the soil in any way in the practice of crop production. The most common operations performed with these implements are ploughing, harrowing, rolling and cultivating. Objects of Tillage. — These may be briefly summarised as follows : — 1. To stir and loosen the entire soil to a sufficient depth for the roots of plants to extend themselves fully. 2. To pulverise the soil and to mix thoroughly its consti- tuent parts. 3. To develop various degrees of structure and uni- formity of soil conditions suitable for the planting of seeds and the setting of plants. 4. To modify the movements of moisture and air in the soil. 5. To place beneath the surface manure, stubble, stalks, and other organic matter, where it will be out of the way and where it will be rapidly converted into humus. B 17 18 CHAPTER III 6. To destroy or to prevent weed growth, and in some cases to control insect pests. Weed seeds dormant in the soil are often (through tillage) induced to germinate, after which they can be destroyed by further tillage. 7. To promote optimum conditions for the development of beneficial soil micro-organisms. 8. To increase the available plant food. 9. To keep the soil in good condition during growth. The most important function of tillage is the preparation of a good seed-bed, which may be defined as " land free from weeds and surface trash, sufficiently mellow to permit easy penetration of the plant roots, sufficiently compact to hold moisture, and to be free from large air spaces, and sufficiently fine in structure to bring many soil particles in contact with the seed and thus to supply an abundance of moisture to the germinating plant.'" Terms Commonly Used. — Even a brief survey of the subject of tillage, such as given herein, necessitates the use of certain terms which are defined below : — Texture has reference to the size of the individual particles of which a soil is composed. Structure refers to the arrangement of soil particles inde- pendent of size, i.e., the grouping of the particles. Tilth has reference to the mechanical condition of the soil and is largely dependent upon the texture and structure of the soil particles. Good tilth implies a thorough, deep and strong granulation resulting in a well-marked crumb structure and, consequently, a friable soil. Plasticity. — " Any material which allows a change of form without rupture, and which wall retain this form not only when the pressure is removed, but also when dry, is said to be plastic."^ Cohesion. — " The tendency of the particles of a soil to stick together and conserve the mass intact."* The cohesion of a soil in the moist condition is generally known as " tenacity." Cohesion is closely related to plasticity. Granulation. — " By this is meant the drawing together of the small particles around a suitable nucleus, so that a crumb structure is produced. It is nothing more or less than a condition brought about by a variable water film and the pulling and binding capacities of colloidal material operating at numberless localised foci."^ In this condition plasticity and cohesion are at a minimum. SOIL MANAGEMENT. 19 Puddling. — This process is directly opposed to granula- tion, and implies a complete breakdown of crumb structure. In a puddled soil plasticity and cohesion are at a maximum. " Light " and " Heavy," when used in connection with soils, are terms referring to their mechanical condition — whether or not they are easily workable. Thus a sandy soil is said to be light on account of the ease with which it is ploughed. These terms have no reference to the specific gravity of soils. Root-zone may be regarded as that layer of soil in which the roots of plants are distributed and in which all the physical, chemical and biological processes are most active. Pore-space is the total volume of the spaces between the soil particles and usually amounts to about 30 to 50 per cent, of the volume of a soil. Structure to a great extent determines the amount of pore space. In puddled soils the granules are deflocculated {i.e., broken down), the pore-space is at a mini- mum and, consequently, the aeration is poor. It has been estimated that in a clay soil of good granular condition 50 to 65 per cent, of its volume is pore-space, while in the same soil when puddled this is reduced to 25 to 45 per cent. The average size of the pores is more important than the total volume, and soils of intermediate texture, and consequently of intermediate size of pores, are suited to a large variety of crops and command the highest prices. Hardpan is a layer of soil that is particularly dense and difficult to penetrate. It may be due to a thin stratum of clay or to the packing caused by continuously ploughing at the same depth ; but in arid areas it is more frequently caused by the cementing together of soil particles under the influence of such substances as lime, iron compounds, carbonate of soda, etc. Soil Tilth. — The promotion and maintenance of good tilth are of fundamental importance in crop production. The state of tilth is closely related to the condition of the soil in regard to granulation. A puddled soil is necessarily in a bad state of tilth , and the promotion of granulation is the first step to- wards improving the tilth. The chief agencies which promote granulation, and con- sequently oood tilth, are as follow : — (a) Wetting and Drying.— The changes in volume due to alternate wetting and drying tend to reduce the soil mass into a large number of small aggregates, i.e., granules. (b) Freezing and Thawing.— The soil moisture on freez- ing exerts an enormous force, shattering the soil. On thawing 20 CHAPTER III the water is further distributed and on freezing again the soil is broken up to a further extent. Drying and freezing have a tendency to coagulate the soil colloids and by so doing promote a granular condition. (c) Plants and Animals. — The root residues of plants upon decay assist granulation. Earthworms and other burrow- ing animals have also a beneficial effect on the tilth of the soil. (d) Addition of Lime. — Lime tends to granulate clay, thus making it more friable. (e) Tillage. — At the correct time, i.e., under proper mois- ture conditions, tillage tends to promote granulation. (f) Drainage assists granulation by the removal of surplus water. (g) Addition of Organic Matter. — Decaying organic matter assists granulation directly, but also to a very large extent indirectly, due to its great changes in volume upon wetting and drying, thus making processes (a) and (b) more effective. The chief agencies which destroy good tilth are : — (a) Excessive Moisture, which causes deflocculation or breaking down of the granules. The poor physical condition of over irrigated (water-logged) soils bears testimony to this. (b) Tillage at the wrong time, i.e., when certain soils are too wet or too dry. (c) Depletion of Humus. — The tendency of soil to settle and bake into large clods after years of cultivation is often due to humus depletion. (d) The Presence of Sodium Carbonate. — This substance has a strong deflocculating effect. It is a characteristic con- stituent of black " brak " in soils. When to Till. — The correct stage at which the various classes of soil should be tilled is indicated when a mass of moist soil pressed in the hand retains its form but does not show free water. A clay soil will become puddled if worked when too wet and if ploughed when too dry will produce a cloddy condition. Sandy soil, however, can be manipulated without detrimental results even when the moisture content is very high or very low. A brief review of some of the fundamental facts relating to plasticity and cohesion of soils will make the matter clear. The following is a short summary of the remarks of Lyon, Fippin and Buckman in this connection : — ' SOIL MANAGEMENT. 21 " The main cause of plasticity is probably the presence of gelatinous colloidal matter, together with a certain optimum amount of water. These conditions facilitate the ready move- ment of the particles, while at the same time sufficient force is exerted to prevent the body from splitting apart at the time of movement or when the pressure is removed or the material dried. When highly developed, plasticity promotes ease in puddling. The three factors that affect plasticity to the greatest extent are texture, granulation and moisture. The finer the texture the higher the plasticity, and the more granular a soil the lower is the plasticity or the tendency to puddle when ploughed. The amount of water is the third vital factor. A soil will exhibit its maximum plasticity at a definite moisture content. This point will be somewhere between the flowing, or viscous, condition and the point at which a soil refuses to mould, or, in other words starts to become crumbly. With a soil such as clay, in which the plasticity is high, ploughing should be done when the moisture condition is such that there is no likelihood of puddling, and yet the soil will turn over with a maximum granulating effect . . . " In general the greater the plasticity of a soil the higher is its cohesion. Cohesion exists under two conditions — when the soil is wet and when the soil is dry. When a soil is moist cohesion is developed by the moisture films and the colloidal materials that may be present (tenacity) ; when dry by the inter-locking of the particles and the deposition of cementing materials. The greatest force, however, is developed by the drying and shrinking of the gelatinous colloidal material. As a general rule the greater the amount of colloidal material, the more firmly the soil is bound together when dry, or, in other words, the greater is its cohesion. " Cohesion is important in tillage operations, in that soils having a high co-efficient of cohesion tend to become cloddy when ploughed and may thus be rendered poor in physical condition. This may be avoided by timing the operation so that the moisture content is somewhere above the point at which excessive cohesion is exerted. As cohesion is not greatly developed, except in a heavy soil, it is only when fine texture is found that such a danger exists. The danger is a double one, for, since high plasticity and high cohesion go together, a soil ploughed when too wet may puddle, while one ploughed when too dry may clod. ..." Every soil has a moisture zone at which neither cohesion nor plasticity is excessive. 22 CHAPTER III The finor the texture the narrower is this zone, i.e., the shorter the period during which good ploughing can be done. Granulation lowers cohesion and plasticity, thereby widening the moisture zone for proper ploughing. It follows then that the promotion of granulation tends not only to eliminate the danger of bad structural relationships, but also to bring the soil into condition for easier and more convenient tillage." Soil Class. — Soils are composed essentially of varying proportions of sand, silt and clay, together with more or less decayed and decaying organic matter. The leading types "of farm soils are roughly classified according to the relative proportions of these constituents present. The chief physical difference between sand, silt and clay is in regard to size of the particles. Thus, we may arbitrarily designate as sand all particles the diametres of which lie betw^een *04 — 1 mm ; as silt, those between 'OO^ — '04 mm ; and clay those smaller than •002 mm. The clay properties are of great importance to fertility from both chemical and physical points of view. No soil con- stituent is more necessary in proper proportion ; at the same time, however, no constituent is more harmful in excess. For practical purposes the sand properties may be regarded simply as the negatives of those which characterise clay, while silt occupies an intermediary position. The percentage of clay present is very generally the dominant consideration in deter- mining the class of a soil. For our present purpose the follow- ing classification of soils, based on their relative content of the three " separates " as defined above will serve : — (a) Coarse sands — consisting almost entirely of sand alone. (h) Sandy soils — about 75 per cent, or more sand and a small amount of silt, but very little clay. (c) Sandy loams — about 50 to 75 per cent, sand, a fair amount of silt and about 10 per cent. clay. (d) Loams — about 40 to 50 per cent, sand, 10 to 15 per cent, clay, and the rest silt. (e) Clay loams — about 15 to 25 per cent. ; the rest sand and silt. (/) Clays — about 25 to 35 per cent, clay ; the rest sand and silt. (fj) Heavy clays — over 35 per cent, clay ; the rest mainly silt. (h) Silt loams — about 50 to 75 per cent, silt ; 10 to 15 per cent, clay ; the rest sand. SOIL MANAGEMENT. 23 (i) Silts — more than 75 per cent, silt and a small amount of sand, but very little clay. The name in every case indicates the fraction whose pro- perties dominate in the soil, except in the case of loams, where the properties of no one fraction dominate. It is understood, of course, that all normal soils contain a small amount of organic matter, and frequently also a small amount of free carbonate of lime. When present in relatively large quantities these substances modify the soil structure to sucli an extent that the above classification is of little or no value, and the soil is given a class name which indicates the dominance of OT-ganic matter or lime, as the case may be. Tillage, Treatment and Characteristics of Various .Soils. — (1) Coarse Sands. — These are quite useless for general farm crops and will, therefore, not be discussed. (2) Sandy Soils. — Their cohesiveness is low, consequently they are light (easily worked) and in extreme cases show a tendency to blow. They are generally poor in plant food and leach readily, especially if the particles arc large. Their reten- tive power for moisture is low, but the movement of soil moisture is rapid. Consequently, they are apt to dry out quickly and very soon suffer from drought. Irrigations must be more frequent than on the heavier types of soil. Sandy soils are usually poor for general farming crops, but since they warm up rapidly they are eminently suitable for vegetable- growing. Moreover, in the intensive cultivation practised by the vegetable-grower, heavier applications of manures are employed than can be afforded by the ordinary farmer. The former finds it profitable to maintain and to increase the fertility of a sandy soil, while the latter may find it un- economical. Organic matter is required to give body to these soils and increase their moisture retention. Consequently, their treat- ment should include a rotation having a leguminous green- manure. Stable or kraal manure is particularly valuable for these soils. The character of the sub-soil must not be overlooked, since a sandy soil resting on a more impervious sub-soil may be a very good soil for general farming. On the poorer types sweet potatoes and rye are the most successful crops. (3) Sandy Loams. — These possess the same character- istics as sandy soils, but in a less marked degree. They are more retentive of moisture and plant-food, fairly easy to ia: 24 CHAPTER III work and, on the whole, are fairly good for ordinary farm crops. Eye, maize, potatoes, peanuts and lucerne are among the best crops for these soils. (4) Loams. — These are the most useful " all-round " soils, combining the lightness and earliness of the sands, with the strength and retentiveness of the clays. They are easily manipulated, do not readily crush or crack, and are usually well supplied with plant-food. Water moves through them « freely yet they do not leach badly. Practically all farm crops 5P thrive satisfactorily on loam soils. They require no special !2: treatment, except such attention to good tillage, manuring, ;3 ^nd the addition of organic matter as is a necessary part of a ^ good farm practice. ■^ (5) Clay Loams, Clays and Heavy Clays. — Soils contain- c55 ing a high percentage of clay are often worthless for ordinary . cropping. However, the lighter types under favourable con- ^ ditions may be considered to be among the most productive of soils. Their characteristic properties are to a great extent the reverse of those of sandy soils. Air and moisture move slowly through them, the percentage of colloidal matter is higher than found in sandy soils, and they are more retentive of moisture and plant-food than the lighter types of soil. They tend to form surface crusts after rains and on drying-out crack badly. The cracking is due to the great shrinkage of the gelatinous colloidal matter when drying-out. The treatment of a clay soil should be of such a nature that it will remedy the chief defect of this type of soil — viz., heaviness. This may be brought about by green manuring, tillage at the right time, drainage where the soil happens to be waterlogged, and by liming. Clay soils are usually rich in plant-food, and plants once established in them thrive well. Grasses and wheat are the most profitable crops on these soils. They are relatively difficult soils to work, because when too wet they puddle readily, and ploughing when too dry results in a cloddy con- dition. When too wet, plants growing in clay soils suffer from poor aeration, and during drought crops suffer pre- maturely. They heat up slowly and are therefore looked upon as cold soils. While sandy soils should be disturbed as little as possible by tillage, clay soils should be worked as often as is economically possible. (6) Silt Loams and Silts. — These soils exhibit the same qualities as clay loams and clays, but to a much less marked SOIL MANAGEMENT. 25 extent. As a rule they possess sufficient tenacity to give the necessary stability without being unduly heavy. They are highly retentive of moisture, yet sufficiently coarse to allow free movement of water, and consequently form some of the best soils for resisting drought. They are well supplied with plant-food, are suited to a wide range of crops and are gener- ally highly productive. In some cases the quantity of fine silt present is so large that the soil is very intractable, closely resembling clay. Liberal incorporation of organic matter will most efficiently remedy this condition. Implements and Their Uses. — According to their effect on the soil implements may be divided roughly into two groups: (1) those that loosen the soil, e.g., ploughs, and (2) those that compact the soil, e.g., rollers. Ploughs. — " The primary function of a plough is to take up a ribbon of soil , twist it upon itself and lay it down bottom side up or partially so. In the process tw^o things result : (1) If the soil is in " proper condition for ploughing it will be shattered and broken up. The furrow slice is sheared or split into many thin layers both vertically and horizontally, result- ing in the complete pulverisation of the soil ; (2) the soil is partially inverted and any rubbish is put beneath the surface.'' The degree to which ploughs will pulverise the soil is dependent on the condition of the soil, the type of plough and the rate at which it is drawn along. Ploughs are of two general types : the mouldboard and the disc. The latter has a lighter draft for the same amount of work done because of its rolling friction as opposed to the sliding friction of the former. While not suited to sod or stoney land, the disc plough is especially effective on very dry, hard soil, and for turning in and covering rubbish. The mouldboard ploughs have more varied shapes and consequently more varied uses than the disc ploughs. For general purposes those having a decided overhang are the most useful, because they have a marked pulverising action. On the other hand, those with a long sloping mouldboard are more adapted to ploughing sod land, beca.use the furrow slice is well packed against its neighbour without being broken. Besides taking the precaution to plough only when the soil is in a suitable condition, some other considerations should also he observed. The furrow slice should not be completely inverted but should be at an appreciable angle with the 2G CHAPTER III horizontal. By so doing a mat of vegetation does not separate the soil from the sub-soil, consequently soil moisture and air move to better advantage, and in subsequent operations the organic matter is better distributed throughout the soil. A drag chain is of service in ploughing under ground heavily covered with vegetation, and a coulter lessens the draft and gives a clear cleavage. Harrowing, if required, should always follow ploughing almost immediately, because the soil is not so liable to form clods as when a period of a day or two or even a few hours is allowed to elapse. The Sub-Soil Plough " consists essentially of a small mole-like point on a long shin. It is drawn through the bottom of the furrow and loosens the sub-soil to a depth of 18 inches to 2 feet without mixing the sub-soil with the soil." Its use in South Africa has never been popular. It is apt to loosen the soil to such an extent that excessive drying-out will take place. Moreover, since the condition of the sub-soil can- not be readily seen, if of a clayey nature, it may be badly puddled by sub-soiling. The Lister Plough is a double mouldboard plough, used in the drier parts for planting maize and sorghum in the furrow. It leaves the ground in ridges which, by subsequent cultivation, are spread over the roots of the plants. It is used chiefly in sandy soils, and is supposed, by promoting lower root growth, to enable plants to withstand drought. Cultivators. — These implements are to-day extraordinarily varied in design. They are used chiefly for destroying weeds, reducing clods and for bringing the soil into a good condition for seeding purposes. Wheeled cultivators are fast coming into general use and have maxiy advantages over other types, e.g., the depth of cultivation can be better regulated, the man operating them is less fatigued, and they are easier to manipulate. The spike-tooth, smoothing, spring-tooth and disc harrows and weedcrs arc used to level the ground as well as to loosen and pulverise the surface of the soil. The spike-tooth is used for shallow cultivation, the spring-tooth for deeper cultivation and the disc harrow often takes the place of the plough in deep soils. Weeders are modified spring-tooth harrows, having numerous long, narrow prongs, used principally for killing weeds while in the seedling stage. Harrows are also used for covering broadcasted seed. The use of cultivators must be regulated according to the stage of development of the crop. SOIL MANAGEMENT. 27 At first inter-tillage of maize may be fairly deep and close to the row, but as the roots extend cultivation must become shal- lower, and more restricted to the centre of the space between the rows. In the early stage of growth, certain crops, like wheat and maize, seem to profit by harrowing, especially when heavily infested with weeds, or when small crusts have formed after showers. Seeders may be looked upon as cultivators, since most of modern make stir the soil while seeding. Packers and Crushers. — The action of the former is to compact the soil, while the latter by crushing clods acts as a pulveriser — the results having something in common. The ijest known of these implements in the Union is the ordinary barrel-roller, although experienced farmers are now using types like the Cambridge roller, which is more of a sub-surface packer. Hard, lumpy ground cannot be pulverised so easily by the barrel roller as by a corrugated roller. The latter has a number of V-shaped wheels, and in its action compacts the soil and leaves a mulch. The clod crushers are either barred, or more commonly, irregular-rimmed types of sub-surface packers, but not so heavy. These break lumps and, unlike the barrel roller, do not tend to push the clods into the soil without breaking them. The planker or float consists of a heavy, broad weight, which is dragged over the soil, the clods are rolled underneath, and by being ground together, their size is effectively reduced. " The soil at the same time is levelled, smoothed and, to a degree, compacted." General. — With due allowance for the genuine difficul- ties which are often encountered, it is generally true that winter ploughing is not sufficiently undertaken in the summer rainfall area. Winter ploughing permits of earlier planting, makes the soil more receptive for the early rains, assists in controlling insect pests and promotes weathering. Many of our farmers are unacquainted with some of the more modern implements, the use of which would not only facilitate their tillage operations, but would also prove profitable. In some areas the soils are shallow and have extremely raw sub-soils. In such cases ploughing should at first be shallow and subsequently gradually increased in depth. Crops grown on these soils injudiciously ploughed are often disap- pointing in growth, having a stunted and yellowish appear- 28 CHAPTER III IRRIGATION. The artificial watering of land for agricultural purposes is termed irrigation. It forms an essential feature in the profit- able production of crops in areas of insufficient rainfall. The undesirable characteristics of the rainfall in many areas of the Union are such that the annual precipitation, although judged sufficient for the requirements for cropping in many parts of the world, must be supplemented by irrigation. The main considerations may be discussed under the headings : (a) Climate; (h) character of the water supply; (c) nature of the soil; (d) surface conditions and topography of the land, and (e) kind of crop grown. (a) Climate. — This has been dealt with in Chapter II. It cannot be over-emphasised that in parts of South Africa where irrigation is practised the evaporation is extraordinarily high — anything from 65 to 90 inches. This has a practical bearing on the duty of water and on the construction of reser- voirs. With more depth many of the farm dams in the coun- try would be more effective, even if less water were stored, than in the shallow dams so often found. (h) The Character of the Water Supply. — The water of highest value for crops is the sewage from large towns. Such water has an added value due to its definite fertilising action. Irrigation with water of this nature is not confined to arid parts, as the larger towns are usually found in humid and sub-humid areas. Next in value to sewage water is the water of streams carrying considerable quantities of suspended matter and valuable salts in solution. The soils of the Nile owe their fertility to water of this nature, and afford an inter- esting illustration. When the sediment from turbid streams settles on sandy soils, they are not only enriched by the plant- food added, but their physical condition is greatly improved by the addition of silt and organic matter. In Egypt the old system of basin irrigation, which allowed the mud to settle out, kept the fields fertile for thousands of years. Recently introduced systems which have not permitted the utilisation of the mud have effected a rapid deterioration in the productivity of the Nile soils. According to Juritz, a sample of Orange River silt from the Prieska District gave the following figures upon analysis : SOIL MANAGEMENT. 29 Per cent. Water 5-99 Organic matter 14'81 Nitrogen '099 Lime 1"444 Potash -473 Phosphoric oxide '221 Juritz says : " The specific gravity of the silt is 2 "03 on the basis of the dry specimen, so that a cubic foot would weigh about 127 pounds. One acre of land covered with this silt to a depth of half an inch, thus receiving a deposit of 1,815 cubic feet, or 115 Cape tons, would, therefore, be en- riched to the extent of 3,314 pounds of lime, 1,086 pounds of potash and 507 pounds of phosphoric oxide." Some irrigation water in South Africa, having its source in dolomitic formations, contains a high percentage of lime. On this account lucerne, a crop preferring calcareous soils, will often thrive on relatively acid soils when irrigated with water of this nature. Apart from the value indicated above, the fact that irriga- tion water often carries enormous numbers of beneficial soil micro-organisms should not be overlooked. On the other hand some waters in South Africa carry & ;.'igh charge of dis- solved salts, and the irrigated lands gradually become impreg- nated with those salts to such an extent thc>kt typical " brak " soil results. In this way the productivity of valuable fields may be ruined. In some cases, too, especially on lucerne lands in the Karroo, the silt carried in flood water forms a hard impervious surface which is very detrimental to the crops. (c) The Nature of the Soil. — The following table indi- cates the importance of the soil factor in irrigation practice : — Approximate Final mean per cent. water of water Per cent, of Soil. content at which available per cent.* crops wilt. water. Coarse sand ... . .. 10-6 3 7-6 Fine sandy loam . .. 18-0 5 13-0 Light silt loam .. 20-9 10 10-9 Clay .. 30-4 17 13-4 Muck .. 250-0 80 170-0 * Maximum capillary capacity. 30 CHAPTER III It will be readily appreciated from the above that soilc rich in humus, as well as those of fine texture, will not only- have a higher percentage of available water than sandy soils without humus, but that they will require irrigation at less frequent intervals. In general sandy soils should receive water frequently, a small amount at a time. Clay soils and those rich in humus should require relatively large but less frequent applications, since their available water content is high, and percolation both slow and small. The nature of the sub-soil is also an important factor. A sandy soil resting on a clay sub-soil will lose water by percola- tion very slowly. Again, a clay soil resting on a sandy sub- soil will require more frequent irrigations than a clay soil on a clay sub-soil, but the former will have a very much better mechanical condition and will suffer less from water-logging. A point often disregarded is, that when grown on a highly fertile soil plants have a smaller water requirement than on a soil of low fertility. For this reason soils should be cultivated where practicable as soon after irrigation as possible, as this enables the various physical, chemical and biological changes to take place more rapidly. Working with maize, Widstoe* obtained the following results : — Pounds of Water Transpired for One Pound of Dry Matter. Soil. Not cultivated. Cultivated. Fertile sandy loam ... 603 252 Fertile clayey loam ... 535 428 Infertile clay 753 682 Infertile sand 454 732 In every case, excepting the abnormal infertile sand, the careful stirring of the soil enabled the plant to produce one pound more of dry matter with a smaller quantity of water than when the soil was not cultivated. Apart from this, with in- creasing richness in available plant-food, the rate of evapora- tion of water from the soil tends to decrease. (d) The Surface Conditions and Topography of the Land.— -On this will depend the method of water distribution. " Flooding " and " furrow " irrigation are the two methods commonly employed. The former method is used as a rule on gently sloping land, while furrows are used where the slope is more decided, where the water supply is limited, and for cer- tain crops like potatoes, tobacco, etc. "^ Flooding is conducted in two ways. One way is to cover the field with a thin sheet of SOIL MANAGEMENT. 31 running water, maintained until the desired degree of saturation has been reached. The alternate method is to cover the surface with a sheet of standing water until the soil has absorbed enough, when the balance is drawn off; or, more simply, to place as much water as is desired upon the land and allow this to be completely absorbed. Flooding is used mostly for crops like the winter cereals and lucerne. The preparation of the land for flooding may be briefly described as follows : — When plougliing is com- menced the entire fields are divided into lands about 10 to ]5 yards in width, so that after the ploughing and harrowing is completed the land forms parallel ridges at the same distance apart ; along these parallel ridges furrows are made by using a double mouldboard plough, which throws the earth both ways and thus forms distributing furrows. The ridge of earth on either side of each furrow serves as a border, which prevents the return to the furrow of the water after it has been thrown out by damming. Too much care can hardly be exercised in the preparation of the land by levelling and obtaining a desir- able slope for crops like lucerne. Often where the land shows a decided slope, a system of terracing may be found necessary, the terraces, of course, following the contour of the ground. In using the furrow method there is a danger of erosion. To minimise this the furrows should closely follow the contour of the ground. The furrows may be from two to five feet apart, depending upon the crop and the soil. Difficulty is experienced in obtaining an even distribution on account of variations in the soil and the length of furrows. Where a furrow is unduly long, the end nearest the supply receives generally considerably more water than the further end. It is, however, a method economical of water, giving a comparatively smaller evapora- tion from the soil than flooding, because the w^hole of the sur- face is not wet. In this connection it is w^orthy of note that a wet soil surface loses water by evaporation more rapidly than the same area of a free water surface. Furrow irrigation is the only practicable method for inter-tilled crops like potatoes or mangels. (e) The Kind of Crop Grown. — The duty of water or the quantity of water needed to mature the crop will vary with the different crops grown. " The absolute duty of water is the total amount that the crop receives by irrigation, by rainfall, and that contained in the soil. It is expressed as acre-inches. The net duty of water is the amount actually delivered to the 32 CHAPTER III farmer through his head-gate."* The duty of water varies according to (1) the rainfall ; (2) porosity of the soil ; (3) fer- tility of the soil ; (4) the frequency of irrigation and amounts applied ; and (5) the average humidity of the air. Crops require to be irrigated when the soil moisture has reached the pomt of lento-capillarity, i.e., the point at which the capillary movement of the soil moisture becomes too slow to satisfy the requirement of the crop. At and below this point the plant is obliged to expend an unnecessary amount of energy in securing water. At this stage the plants become flaccid and a slight change of colour in the leaves and stalks is apparent. In general irrigation should be curtailed during the early development of crops, so that a deep root development may be stimulated. In the case of grain crops, irrigation should be liberal from the time of flowering to just before maturity, because during this stage translocation of food material and various anabolic processes which involve the use of water are most active. In South Africa the most common error of farmers who have abundance of water at their disposal is over-irrigation, particularly during the early stages of growth. Often, too, the fact is overlooked that, although increased irrigation may give increased yields, it is apt to do so at an increased water cost. Where the amount of water available is limited, and land relatively cheap, the yield per acre is not as important as the yield from a given quantity of water. Widstoe"" found that the amounts of dry matter in pounds produced by the same quantity of water (30 acre inches) spread over one acre and four acres respectively were as follow : — Crop. One acre. Four acres. Wheat 6,951 22,180 Maize 15,294 43,028 Lucerne 8,133 3,272 Potatoes 3,660 10,920 The approximate amount given per irrigation may be taken as 3 inches for a light, 5 to 6 inches for an average, and 8 inches for a heavy irrigation. The irrigation of specific crops is dealt with in later chap- ters in which the various crops are discussed. It should be borne in mind that for all crops, where possible, the soil should contain sufficient moisture at the time of planting to ensure ger- mination and a vigorous seedling growth. Effect of Irrigation on the Crop. — Liberal irrigation tends to delay maturity, to increase the percentage of carbo- SOIL MANAGEMENT. 33 hydrates and ash, and to decrease the protein content of the crop. Besides these effects it is apt to encourage lodging in the cereals and to predispose them to disease, e.g., rust. Injudi- cious irrigation often has the effect of promoting vegetative growth at the expense of fruiting. Losses due to frost may sometimes be lessened by irrigating when frost is expected. DEAINAGE. Land drainage is the quick removal of the excess of free water from the pores of the soil. Effects of Drainage. — (1) Gravitational water is removed by drainage from the pores of the soil and replaced by air, thus ensuring a sufficiency of oxygen. A deficiency of oxygen restricts plant growth, and therefore the crop yield. Moreover, this deficiency results in an increased activity of anserobic bacteria, with the result that nitrates may be reduced to injurious nitrites or even to nitrogen gas, which is then lost from the soil. Harmless ferric compounds may also be changed into harmful ferrous compounds. Further, by drainage the water is lowered, thus enabling crops to root deeper, and, what is more important, abnormal fluctuations of the water-table are reduced. Crops, which may be thrifty with a water-table at a reasonable depth, are in many cases destroyed should the water-table rise considerably for any length of time. A water-table fluctuating widely in its dis- tance from the surface is often more inimical to plant growth than one which is relatively stationary, even if comparatively shallow. (2) In a water-logged soil the crumb structure becomes broken down, and the tilth of the soil suffers in consequence. Under these conditions aeration, too, is poor. Drainage in- duces the formation of granules, thus improving the tilth, and incidentally allows longer periods for tillage operations after rains or irrigation. (3) Drainage does not remove available water. In fact, by reason of the improved tilth of the soil and the deeper pene- tration of the roots of plants, a larger amount of capillary water is made available, and it is found that on drained land crops withstand dry weather better than on land intermittently water-logged. The fluctuations of soil moisture are much greater near the surface than deeper down, where the moisture content is rela- 34 CHAPTER III tively uniform ; therefore the deeper the root zone the more uniform is the water supply hkely to be. (4) Drained soils have a higher average temperature than similar soils in an undrained condition, consequently an earlier growth is obtained on the former than on the latter. Sandy soils, as compared with clay soils, are looked upon as warm and early, due to the fact that the water-holding capacity of clay soils is higher than that of sandy types. (5) The supply of available plant food is increased by the better aeration, higher temperature, deeper root penetration, better tilth, better moisture supply, and more active and fav- ourable bacterial growth in the soil, all of which conditions result from improved drainage of a wet soil. The organisms that cause the decay of roots and manure and those that use the free nitrogen of the air are particularly affected in a beneficial way. (6) Drained land is more receptive of moistujre either in the form of irrigation or rain, and because of this incidentally ciiecks erosion. (7) The provision of adequate drainage prevents the accumulation of brak salts in the surface soil. This is in fact the only method of keeping land permanently free from harm- ful accumulations of brak salts in areas where the trouble is common. The necessity for drainage is indicated when the tilth of the soil is poor, where the crumb structure of the particles is absent, where the water-table is within 2 to 3 feet of the sur- face, and where the growth of the plants is of an unthrifty character and the vegetation of a yellowish colour. Where land is relatively cheap, as in South Africa, artificial drainage will be restricted to land which for some outstanding reason requires it, e.g., horticultural land near a homestead. How- ever, in parts of Natal and Griqualand East, where arable land is often scarce, due to the mountainous character of the country and the high rainfall, drainage efi'ected by open furrows has been profitable and necessary. In many parts of the country land under irrigation might be profitably drained with some cheap form of under-drainage. Types of Drains. — The oldest, apart from open surface ditches, but the least efficient, are those which are made by placing loose stone or closely packed logs in furrows which have been dug with the necessary fall, and then filling in with soil. These are usually short lived. SOIL MANAGEMENT. 35 The objection to open surface ditches is that they are diffi- cult to keep free from weeds and, further, that they restrict cultural operations and occupy valuable land. However, a great deal of unprofitable land can be reclaimed by this method. Care should be taken that the sides are sloping so that they do not become under-washed and subsequently collapse. The most efficient system is tile-draining. Two kinds of tile are in common use — (1) clay tile, well burned, cylindrical and straight, and (2) concrete tile, both being made in about 12-inch lengths. These are placed end to end at the bottom of the furrows, the joints being uncemented. The water per- colates through the sides of the tile and through the joints and then down the drain. System of Drainage. — Naturally the outlet should be towards the lowest part of the land, and the mains should run along the lines of natural drainage. The laterals are generally single lines serving as collecting drains and usually arranged in parallel systems. Intercepting or cut-off drains are those laid at the base of a slope to collect the water that the heavier sub- soil layers are carrying to the lower level lands. Depth and Distance Apart of Drains. — These are matters of extreme importance and are governed by a number of considerations. From the point of view of drainage, the sub-soil is of more importance than the surface soil. In general the finer the texture the shallower the drains and the closer together must the lines be placed. The depth varies from 2 feet in heavy soils to 4 feet in more open types. In clay soils the drains are usually placed from 40 feet to 60 feet apart, whereas in open sandy soils they may be placed from 80 to 150 feet apart. Naturally, too, in most soils, except heavy clays, the deeper the drains are placed the wider should be the inter- vals between the lines. The size of the tile will vary according to the area to be drained and the grade. The laterals usually consist of 4 to 6 inch tiles, while the sub-mains and mains are composed of tiles 9 and 12 inches in diameter. The grade should be as steep as possible, with a fall not less than six inches in every 100 feet. Obstructions may be caused by roots, animals and silting. Usually little difficulty is found in locating these, and if the ends are closed with small meshed wire-netting, small animals will be prevented from entering. It is remarkable how seldom even a deep-rooted crop like lucerne will obstruct a drain. 36 CHAPTER III BEAK SOILS. The two great factors withholding from cultivation millions of acres of land in arid and semi-arid parts of the globe are drought and brak ; and even if the drought factor is elimin- ated by irrigation, the presence of brak may still prevent suc- cessful crop production. In fact, practical experience has demonstrated time and again that the brak evil may be greatly aggravated by irrigation, and in many cases brak salts appear in the surface soil in harmful quantities only after the land has been brought under irrigation. Brak is commonly known as " alkali " in America and other countries. It refers to the presence of soluble salts in the soil in sufficient concentration to injure plants, and may include salts which in smaller concentration are decidedly beneficial to plant growth, e.g., nitrate of soda. All arid soils are, of course, not necessarily affected with brak, but arid conditions in general are favourable to the accumulation of brak salts, whereas humid conditions are not. In the latter case abundant rainfall, coupled with natural drain- age, will effectively prevent any harmful accumulation of soluble salts. Arid and semi-arid conditions prevail over a great part of South Africa, and brak is very commonly present in the soils of these areas. Furthermore, irrigation is playing an ever- increasingly important part in South African agriculture, so that the brak problem demands, and must receive, particular attention in this country. Frequently the concentration of brak salts in the surface soil is not as yet sufficient to injure crops, but unless proper precautions are observed, the almost invariable natural tendency is for the concentration to increase. Crops vary greatly in their tolerance for brak soils, so that concentrations which are decidedly injurious to certain crops may have no harmful effect upon others. There is, however, a limit to the amount of brak which can be tolerated by any crop, and occasionally the concentration is so high that the growth of ordinary farm crops is impossible. The natural vegetation of such lands is generally confined to plants useless to man, known commonly as " saline vegetation." Notable exceptions occur, however, as instanced by much of the Karroo vegetation which forms valuable pasture, and by Australian salt bushes, which are readily eaten by all kinds of stock. In SOIL MANAGEMENT. 37 extreme cases brak lands are wholly destitute of vegetation, or bear only such saline growth as is rejected by all domestic animals. Keclamation of land badly affected with brak is very costly, and frequently not worth attempting, save in the case of excep- tionally valuable land ; but if the brak tendency is recognised while the concentration is still small and comparatively innocuous, the adoption of simple precautionary measures may prevent further accumulation and maintain the crop producing power of the land indefinitely. A noteworthy feature of brak soils is the fact that high concentration of soluble salts generally coincides with richness in plant food, so that these soils are characterised by high potential fertility, which manifests itself in the good crop yields following removal of the brak salts or their reduction to innocu- ous concentration. Nature and Composition of Brak. — In general brak may consist of carbonates (or bicarbonates), chlorides, sulphates and nitrates of sodium, potassium, calcium and magnesium, with the following reservations : — (1) Sodium salts are almost invariably the chief constitu- ents, particularly the carbonate (or bicarbonate), chloride and sulphate. (2) The bicarbonate and sulphate of calcium are not suffi- ciently soluble to be directly injurious. (3) The quantity of potash salts present is generally low, forming as a rule from 5 to 20 per cent, of the total salts. (4) Sodium phosphate is fairly frequently a constituent of brak salts, though never present in large quantities. It may form up to about 4 per cent, of the total salts present. Two general types of brak are recognised, the " black " and the " white " varieties. Black Brak is characterised by the presence of sodium carbonate (or bicarbonate) in considerable quantity. This sub- stance has a solvent effect upon soil humus, thus imparting a dark colour to the soil solution and any incrustation that may appear on the surface of the soil. As a rule there are also pre- sent more or less sodium chloride and sulphate, a little sodium phosphate (due to the solvent effect of sodium carbonate upon insoluble phosphates in the soil), and probably small amounts of potash salts, but no sulphates or chlorides of calcium or magnesium, and very little or not nitrates of any description. White Brak consists essentially of chloride and sulphate 38 CHAPTER III of sodium, together with smaller quantities of the correspond- ing salts of potassium, and very frequently more or less sul- phate and chloride of magnesium and calcium. When these salts come to the surface of the soil they may frequently be seen as a white incrustation. Little or no sodium phosphate is found in white brak, but occasionally large amounts of nitrates are present, up to 20 per cent, of the total salts. The black variety is far more mjurious than the white in its effect upon both soil and plant. Origin of Brak Salts. — For the present purpose it is unnecessary to consider in any detail the various natural agencies responsible for the existence of brak in soils. Brak salts are, of course, ultimately derived from the decomposition of soil-forming minerals. When leaching occurs the soluble salts are carried away, but in comparatively dry areas gradual accumulation during ages of decomposition may account for the brak condition of the present. In other cases the underlying shales and sandstones have been found to be richly impregnated with pre-formed soluble salts, which readily account for the presence of these salts in the soils. Such shales and sandstones are said to have been deposited in past ages from inland seas and lakes containing large quantities of soluble salts. In still other cases the existence of brak is attributed to more recent evaporation of saline lakes and shut-off arms of the ocean, the soluble salts of course being left in the soil. The occasional occurrence of considerable quantities of nitrates in soils has been traced in some cases to pre-formed nitrates found in the underlying shales and sandstones ; in others it is attributed to intense local nitrogen fixation by non-symbiotic bacteria. Secondary reactions are liable to occur in the soil with the possible formation of carbonates of sodium and potassium from other less injurious salts of these metals. Finally, of great significance in present soil management, the use of impure water for irrigation may at least in part account for the presence of harmful salts in the soil. Seepage water from brak areas or from rock formations rich in soluble salts should never be used for irrigation. The safety limit of soluble salt content of irrigation water will vary according to the soil, the crop, the amount of water applied, the drainage and other factors. Hilgard states that 685 parts per million should be the limit under average conditions, though as litt'le as SOIL MANAGEMENT. 39 342 parts per million of sodium carbonate alone may cause seri- ous injury in three or four years, while as much as 2,740 parts per million of the less toxic salts would not be harmful. Mackie considers from 600 to 700 parts per million to be the limit when the salts are mainly sodium bicarbonate and sodium chloride ; when the salts are largely of the sodium sulphate type, larger quantities are permissable. Harris considers that under aver- age conditions the limit is 500 parts per million for sodium carbonate, 1,000 parts for sodium chloride, 4,000 parts for sodium sulphate, and for the mixed salts, 4,000 parts per mil- lion ; on poorly drained soils the limits must be placed lower. Movement of Brak Salts in the Soil and the Effect OF Irrigation. — The greatest problem in connection with the utilisation of brak soils is to control the movement of the sol- uble salts. If kept in the lower depths of the soil, brak salts would be harmless, but it is their natural upward movement and gradual accumulation in large quantity in the top foot or two that finally ruins the land. Under natural conditions in arid regions, when the water- table is far below the surface, the soluble salts tend to accumu- late, not at the surface, but at some little distance beneath, approximately at the lowest point to which the natural rainfall penetrates, perhaps three or four feet deep. The actual point of maximum accumulation will vary according to the rainfall and the porosity of the soil. Any soluble material in the upper soil is carried downward by percolation, and the subsequent upward movement of the moisture by capillarity is greatly restricted, because the rather deep-rooted vegetation extracts most of the water rapidly at some depth below the surface, and at the same time the rapid drying of the surface soil reduces the upward capillary movement of the moisture. Thus the soluble salts are generally not brought to the surface to any appreciable extent. When such lands are brought under irrigation, however, this condition of balance is upset. The' soil is kept so much more moist that capillary action is greatly increased and con- siderable evaporation takes place at the surface. The soluble salts then move upwards and are left at or near the surface. When drainage is poor the condition is still worse, for then the water-table may be raised to within a few feet of the surface. Soluble salts washed downwards in such cases go only as far as the water-table, and are later readily drawn up to the surface again. 40 CHAPTER III Harmful Effects of Brak Salts.— The injury to crop production due to the presence of brak salts in the soil is partly direct, due to their harmful effect on the plant and germinating seed, and partly indirect, due to their effect upon the soil and its micro-organic flora. Summarised briefly, the following are the most important points : — A. Jnjury to Plants.— (1) Plasmolysis of Plant Cells. — The high concentration of salts in the soil solution retards the rate of water absorption and therefore also retards general de- velopment. In extreme cases where the soil solution is more concentrated than the cell sap of the root hairs, the movement is reversed, water passing from the root hairs into the soil solu- tion. This results in plasmolysis of the plant cells followed shortly by the death of the plant. (2) Gemiination of Seeds. — If the soil solution is concen- trated enough, water absorption may be entirely prevented, and the seed, therefore, fail to germinate. In this case it merely lies dormant in the soil. In less extreme cases the water absorption is retarded and, therefore, germination is delayed. In such cases the seed may take three or four times the normal time to germinate. (3) Structure of Plant. — The presence of considerable quantities of soluble salts appears to affect the structure of plants. Harter, working with cereals found a very noticeable thickening of the cuticle and outer walls of the epidermal cells occurred, and a conspicuous bloom or waxy deposit formed on the surface of the leaves. (4) Corrosion of Surface. — Particularly noticeable in the case of trees which have become well-established, and later subjected to a gradual accumulation of soluble salts at the sur- face. The effect is to corrode the plant at the base of the stem or trunk, i.e., at the root-crown. The bark at this point becomes dark in colour and crumbles away readily. The corrosion may go deeper and partly or completely prevent the upward passage of food from the roots to the upper parts of the plant. This effect is most marked in the case of the car- bonates of sodium and potassium. (5) Direct Toxicity. — It is possible that certain brak salts exert a direct toxic effect on the plant, but to what extent this is a factor in the general injury to the plant is not know^n. Some of the salts are extremely toxic when alone in far lower concentrations than frequently occur in soils with little SOIL MANAGEMENT. 41 or no harmful effect ; but combinations of several toxic salts in solution often show greatly reduced toxicity, apparently due to antagonism between different ions, e.g., highly toxic solu- tions of magnesium salts may be rendered innocuous by the addition of a small quantity of a soluble calcium salt. The absence of pronounced toxic effects in many brak soils is pro- bably due to such antagonism among the various salts, and perhaps partly to adsorption of soluble salts by the soil. B. Injury to Soil. — (6) Structure. — Carbonates of sodium and potassium are strong deflocculants. The presence of appreciable quantities of these salts in the soil then leads to puddling with all its characteristic harmful effects upon mechanical properties. Surface crusts may form of such hardness that seedlings cannot push through. Most of the other common brak salts are flocculants and do not injure structure, except in so far as they may be changed in the soil to the harmful carbonates rcfen-ed to, e.g., repeated applica- tion of nitrate of soda to lands is frequently observed to cause deterioration in physical condition, due not to the nitrate it- self, but to the residue of sodium carbonate which is apparently left in the soil by this fertiliser. (7) Hardpan Formation. — The presence of brak in soils seems to facilitate the formation of hardpan. (8) Movement of Soil Moisture. — Tn general capillary movement is retarded by the presence of brak salts, though in low concentrations this effect is very small. Sodium carbon- ate appears to differ from the neutral salts in that it gives a much greater capillary rise than the neutral salts in equal concentration. (9) Evaporation of Moisture. — Evaporation from the soil is lessened by the presence of brak salts, as these reduce the vapour tension of the soil solution. For this reason, brak spots in soils tend to remain moist much longer than the surrounding normal soil. C. Injury to Micro-Organisms. — (10) While a great deal of the present evidence is conflicting, it seems to indicate that decreased bacterial activity is an important phase of the injury to crop production caused by brak salts. Ammonifica- tion, and nitrification in particular, are greatly retarded, in some cases at least. Reclamation of Brak Soils. — Observations in regard to the growth of crops, coupled with chemical analysis, will clearly indicate the presence of brak. The limit of the 42 CHAPTER III quantity of salts that may be present without injury to crops varies greatly, depending upon the kind of salts present, the nature of the soil, the crops grown, and the drainage. In any case it is highly important to recognise the brak tendency before definite injury to crops occurs, so that measures can be taken to prevent harmful accumulation at the surface. The economy of methods of reclamation must be carefully studied ; it may frequntly not pay to reclaim cheap land which is badly affected. Briefly, the chief measures for preventing future harmful accumulation in present mild cases, and for reclaiming badly affected lands, are as follows : — (1) Reduction of Surface Evaporation. — Practise deep and thorough tillage, and maintain an efficient surface mulch. (2) Changing the Form of the Soluble Salts. — This refers particularly to carbonates of sodium and potassium, the most harmful forms. (a) By application of finely ground gypsum (sulphate of lime). The soluble carbonates are thereby at least partly changed to less injurious sulphates. Na2C03 + CaS04— > Na.S04 + CaC0. In order to be effective, the application of gypsum must be several times as great as the amount of NaoCO, present. It is said that gypsum will have no effect if the soil or irriga- tion water used contains appreciable quantities of sulphates. (b) Other methods suggested are based upon neutralisa- tion of the soluble carbonates with acids. Symmonds has used nitric acid with good results, and Lipman found sulphuric acid also useful. The latter has suggested the use of applica- tions of sulphur. This is oxidised in the soil by bacteria to sulphuric a^id. (3) Removal of the Salts from the Surface Soil. — (a) By encouraging the rise of the salts to the surface and then scraping off the incrustation. (h) By flooding heavily and thus washing the soluble salts into the lower soil depths well beyond the reach of the roots of crops. The salts will, of course, rise to the surface again after a time. (c) By encouraging the rise of the salts to the surface, and then flooding over the surface and running the water off the land. SOIL MANAGEMENT. 43 (4) Drainage. — The institution of efficient drainage is the only really effective and permanent remedy. In this way the water-table can be kept at a desirable distance from the surface and prevented from rising after irrigation. With good drainage the soluble salts can then be washed out of the soil by successive floodings. When much soluble carbonate is present, the percolation of water may be facilitated by previous application of gypsum or large quantities of coarse straw. While, unfortunately, rather costly good drainage is the secret of brak prevention. (5) Avoidance of the Use of Unsafe Irngation Water. — Before being used for krigation, water should always be analysed to determine whether it contains harmful quantities of dissolved salts. (6) Growth of Brak-Resistant Plants. — Absence of vege- tation promotes surface accumulation of brak salts ; so it is desirable to maintain some kind of plant growth, even if not very useful. Crops differ greatly in their tolerance for brak salts, some, such as citrus, being extremely sensitive, while others, such as various types of salt-bushes, are highly resistant. REFERENCES. » U.S.D.A. Bui. 320. - Soils, Their Properties and Management. Lyon, Fippin and Buckman. ' A Study of the Agricultural Soils of the Cape Colony. Juritz. ■• Principles of Irrigation Practice. Widstoe. ^ Soil, Physics and Management. Mosier and Gustafson. • Soil Alkali. Harris. ■> Soils. Hilgard. « The Soil. Hall. ^ Soil Conditions and Plant Growth. Russell. CHAPTER IV SOIL MANAGEMENT (continued), FERTILISER PRACTICE, GREEN-MANURING AND WEED CONTROL. FERTILISER PRACTICE. Without attempting to take up the subject of fertiliser practice in detail the authors have considered that a very brief discussion of the matter, giving some of the underlying prin- ciples, as applied to South African conditions in particular, would be helpful to some readers. A fertiliser may conveniently be defined as a substance which is applied to soil for the purpose of directly increasing the amount of available plant food present. The fertiliser itself carries the plant food in question, and is to be distinguished from other substances occasionally added to soils, which may stimulate the production of available plant food from the soil's reserves, but do not themselves contain the plant food in question; e.g., gypsum contains no potash, but when applied to soil it is known to increase the availability of the soil's supply of potash. Such substances are more correctly termed " stimulants." Of the various plant foods known to be indispensable for the proper growth and development of crops, nitrogen, phos- phoric oxide and potash are the ones whose supply is most likely to be deficient in soils. In some cases the supply of lime may be insufficient to meet the food requirements of crops; as a general rale, however, the lime supply is of interest chiefly by virtue of its indirect effects on the soil. It is possible that rare cases may occur where the supply of certain other plant foods, such as sulphates and magnesia, is deficient, but none such has been definitely recorded. Available Plant Food. — The productivity of a soil, so far as the food supply is concerned, is determined not so much by the total amount of plant food present as by the rate at which the reserves of plant food become available for nutrition of crops. There is, however, generally a close relationship between these two factors, and under normal conditions large reserves of plant food, as determined by chemical analysis, 44 SOIL MANAGEMENT. 45 usually indicate a sufficiency of available food. A deficiency in respect of any one plant food implies an insufficient produc- tion of available food from tbe soil's reserve supply of that particular constituent. This will generally correspond with an insufficient reserve supply, but not necessarily so. The generation of readily available plant food in soil is influenced largely by the mechanical condition, particularly in regard to aeration. Another important consideration is the presence of actively decaying organic matter, as the by-products of this decay process aid in rendering plant food constituents soluble. Virgin soils generally contain an accumulated supply of readily available plant food, and are, therefore, usually highly productive when first brought under cultivation. Continuous cropping without the addition of fer- tilisers or manures, however, rapidly exhausts the available food supply and leads to diminished yields, the condition being aggravated by the depletion of humus and the consequent deterioration in mechanical condition. Plant Food Deficiencies. — In connection with the rela- tive supplies of the various plant foods, it is well to bear in mind the " law of the minimum " as applied to soils. This may be stated as follows : — " Any essential plant food that exists in the soil in relatively small amount as compared with the other important constituents naturally becomes the con- trolling food factor in crop development. Any reduction or increase in the supply of this constituent will cause a reduc- tion or increase in the crop yield " ; or, more briefly : " The crop yield is determined by the quantity of that plant food which is most deficient in the soil." Rational fertihser prac- tice is based upon the application of this law, and obviously implies the recognition of the specific plant food deficiencies of the soil. The manurial requirements of soils may be determined either by chemical analysis or from the results of accurately controlled field experiments. (a) Soil Analysis. — By chemical analysis we obtain an invoice of the soil's total reserve supplies of the various essen- tial plant foods. A marked deficiency in respect of any one constituent generally indicates that addition of this constituent is necessary. Availability is, however, not always propor- tioned to the total supplies, and deductions from chemical analyses may be somewhat at variance with field observations. Analytical methods have also been devised for the determina- tion of readily available plant food in soils at the time of 46 CHAPTER IV analysis. These results, considered in conjunction with the total reserve supplies, in most cases make clear the manurial requirements of the soil. (b) Field Experiments. — In this method a representative portion of the land is divided into a number of equal plots, certain of which are fertilised, and others (every second or third plot) left untreated as " checks." Standard one- constituent fertilisers are used, e.g., blood meal as a source of nitrogen, superphosphate as a source of phosphoric oxide, and sulphate of potash as a source of potash. These are applied both singly and in combination. The effect of each fertiliser treatment is gauged by the increase of yield, as com- pared with the untreated plots. If the land chosen is uniform, the plots properly laid out, and the underlying principles of experimental work observed, this is probably the most satis- factory method of ascertaining a soil's deficiencies. The results of the first year will often indicate positive require- ments. The farmer is advised, before undertaking a heavy expenditure on fertilisers, to test these in some simple manner on his land. The chief points for him to observe are to choose uniform and representative ground, to have unraanured plots as checks contiguous with the treated plots and, if possible, to duplicate or even triplicate the series. Eelative deficiencies or excesses of those plant foods with which we are most concerned in fertiliser practice, if marked, can frequently be detected by merely studying the appearance of crops growing on the soil in question. Nitrogen appears to be closely associated with the rate of growth. Insufficient nitrogen results in a weak, stunted growth and a poor colour. Excess, on the other hand, pro- motes a vigorous vegetative growth of good colour, often at the expense of fruiting and the strength of the stems ; de- creases the plant's resistance to disease (e.g., rust in cereals), delays maturity, and tends to increase the nitrogen content of the crop. Phosphoric oxide seems to be associated particularly with root development and the fruiting process. A sufficiency of phosphoric oxide to some extent counteracts the ill effects of an excessive nitrogen supply. It promotes root development, hastens maturity, and stimulates fruiting; thereby ensuring, in the case of grain crops, a larger proportion of grain to straw. Potash is said to be closely concerned with the formation of carbohydrates in the plant. A sufficiency of potash apparently strengthens the vegetative tissues, thereby increas- SOIL MANAGEMENT. 47 ing resistance to disease, and assists in the formation of plump, heavy seed; and more particularly of good tubers, roots, bulbs and fruit. The most marked deficiency of South African soils as a whole, as shown by chemical analysis, field tests, and practical experience, seems to be in respect of phosphoric oxide. With reference to Transvaal soils, Juritz says : " An average of 100 analyses of Transvaal soils out of various parts of the Province, done by the Department of Agriculture, show the average soil to be poor in phosphates, medium in nitrogen and good in potash." Broadly speaking, this generalisation may well be applied to the soils of the other Provinces too. Throughout the Union, with rare exceptions, the judicious use of phosphatic fertilisers is necessary and profitable. With regard to nitrogen, deficiency, though not so general, is fairly common, and is invariably associated with a de- ficiency of soil humus. In the summer rainfall area nitrate formation in the soil is rapid during the summer, and the need for nitrogen is not so urgently felt by summer crops as by winter crops. In any case, the demands for nitrogen are most economically met by leguminous green-manuring, or by the incorporation of stable or kraal manure with the soil, or by a combination of both. In this way not only is the nitrogen supply increased, but a large quantity of humus is added to the soil, and in the case of animal manures considerable quantities of phosphoric oxide and potash are also added to the soil's supply. Potash is usually present in sufficient quantities, and its application is seldom profitable in South Africa, except on certain sandy soils, and possibly on even better supplied soils where potash feeders such as potatoes, tobaccp, etc., are grown. Commercial Fertilisers. — The following are a few of the principal commercial fertilisers available to the farmer in South Africa : — (1) Nitratf Soda. — Containing about 15 per cent, nitro- gen immediately available to crops. It is soluble in water and apt to be leached out of the soil by heavy rains. For this reason it is usually applied in comparatively small quantities as a top dressing after the crop is up. (2) Sulphate of Ammonia. — Containing about 20 per cent, nitrogen, which rapidly becomes available. It is less liable to be leached out of the soil than nitrate of soda. 48 CHAPTER IV (3) Nitrate of Lime. — Containing about 13 per cent, nitro- gen immediately available. It is similar to nitrate of soda in most respects. (4) Blood Meal. — Containing about 12 per cent, nitrogen, which becomes available fairly rapidly. (5) Government Guano. — Containing about 10 per cent, nitrogen, 11 per cent, phosphoric oxide, and a little potash, all fairly readily available. Its composition is liable to vary somewhat. (6) Superphosphate. — Containing, if of good grade, 15 to 20 per cent, phosphoric oxide. Soluble in water, and therefore immediately available to crops. (7) Bone Dust. — Containing about 3 to 4 per cent, nitro- gen and 23 to 24 per cent, phosphoric oxide. Should be as fine as possible, as fineness increases availability. For best results should be apphed early. (8) Basic Slag. — Containing about 8 to 20 per cent, nitro- gen and 20 per cent, free lime. It is slow in action and should, therefore, be applied early. It is said to act best on heavy, wet soils. (9) Sulphate of Potash. — Containing 45 to 50 per cent, potash in readily available form. (10) Muriate of Potash. — Containing 50 to 55 per cent, potash in readily available form. Muriate (i.e., chloride) of potash seems to injure the quality of certain crops, like tobacco. Use of Lime. — It is commonly stated that all normal fer- tile soils should contain a certain amount of free lime (in the form of calcium carbonate). Total absence of free lime gives rise to the condition known as " acidity " or ' sourness," which is unfavourable to many plants and soil micro- organisms. Lime exerts both chemical and physical effects in the soil, which may be summarised as follows : — (1) It prevents the formation of " acidity," thereby stimu- lating the activity of desirable micro-organisms in the soil. Notable among these are micro-organisms engaged in the de- composition of organic matter, nitrification of organic nitro- gen, and fixation of atmospheric nitrogen. Stated otherwise — the effect of lime is to stimulate the decomposition of organic matter and the production of nitrogenous plant food. (2) By interaction with mineral compounds in the soil, it stimulates to some extent the production of available potash and phosphoric oxide from the soil's reserve supply of these plant foods. In this respect it must be classed as a " stimu- lant," not " fertiliser." SOIL MANAGEMENT. 49 (3) It gives rise to soluble bicarbonate of lime in the soil, which flocculates clay, thus greatly facilitating granulation. Therefore, the addition of lime greatly improves the mechanical condition of soils that are inclined to be " heavy." (4) In cases, probably rare, where the soil not only lacks free lime, but is also markedly deficient in other compounds of calcium, addition of lime may have a beneficial effect by virtue of the plant food element calcium which it furnishes in readily available form. In this respect it acts as a direct " fertiUser." Of greatest importance are the effects of lime as related to soil activity and mechanical condition, and from the point of view of these functions it is termed a soil " amendment." Agricultural experience in Europe and America shows that the presence of free lime commonly plays a controlling part in soil fertility, and it has frequently been found that acid soils of low fertility become highly productive after lime has been added. Under South African soil and climatic conditions, how- ever, it should be stated that, except in the case of a few crops, such as sugar cane and certain legumes, practical experience has not clearly estabhshed the genuine necessity of a sufficient supply of free lime in the soil. On the score of economy, therefore, the advisability of liming soils for field crops in South Africa, with the exceptions already noted, is still problematical, although there is no doubt as to the beneficial effect of lime upon the mechanical condition of heavy soils. On some acid soils, however, where transport facilities are reasonable, and lime easily and cheaply obtainable, liming will, no doubt, be found to be lucrative; more particularly on soils that are naturally rich in humus, or have recently received large applications of organic matter in the form of manure or green-manure. Lime may be applied to the soil in the mild form of finely- ground hmestone, commonly known as " agricultural lime," or in the more energetic caustic form of slaked lime. The former is generally to be preferred, because the energetic action of slaked lime is liable to cause excessive decomposition of organic matter, leading to rapid depletion in this respect. In the case of heavy soils, where the mechanical effect is chiefly sought after, slaked lime will cause more rapid improvement. In general, lime should be applied early, by spreading over the ploughed soil and then harrowing it in. 60 CHAPTER IV Maintaining Fertility. — The most important economic problem of any extensive agricultural country is to maintain the fertility of the soil. In young countries, where land is plentiful and cheap, this is at first not so evident, but the gradual reduction of the productive power of the land, to- gether with increasing population, must in time compel recognition of this truth. The frequent periods of famine in India, China and Kussia, due largely to improvident methods of farming, afford cases in point. The ideal of agricultural practice, in the case of highly productive lands, is obviously to maintain crop yields per- manently at this high level, and, in the case of poor lands, to gradually raise the productivity to a higher level, and then maintain it permanently ; due attention being paid to economy in either case. Under highly intensive systems of farming this ideal is comparatively easy of achievement, because relatively small areas are cultivated and crop yields are large, and so more efficient methods of management are possible. Over the greater part of South Africa, especially in the summer rainfall area, the farming is largely extensive in nature. In many agricultural districts, truly intensive methods are hardly possible, because, apart from the fact that on the whole the soils are not rich in plant food, the rainfall is extremely erratic in regard to both quantity and distribu- tion. The areas under cultivation are freauently far larger than can be efficiently managed, and as a result the average level of production is extremely low. As a fairly general rule, however, it can hardly be doubted that the adoption of some- what more intensive methods would pay. While the maintenance of fertility denends primarily on the plant food relations in the soil, the absolute necessity of good tillage must be kept in mind, and the system of farming practised must be such as will not lead to deterioration in mechanical condition, nor affect adversely the activities of useful soil micro-organisms. Soil fertility cannot be maintained in field practice by use of commercial fertilisers alone. On the score of economy, firstly, the idea is untenable, because there are cheaper methods of supplying certain of the requirements : notably in regard to nitrogen, which is the most costly of all commer- cial plant foods. In the second place, commercial fertilisers provide little or no humus, and the inevitable depletion of the soil humus leads to bad tilth and decreased availability of other plant foods in the soil. SOIL MANAGEMENT, 51 Nitrogen and humus go hand-in-hand and proper atten- tion to the humus supply will in part or completely solve the nitrogen problem. The best methods of supplying humus and nitrogen are : — (1) By crop rotation, including a green manure; prefer- ably leguminous. {See next section.) Where practicable, the residues (straw, etc.) of other crops should also be returned to the soil. (2) By the use of animal manures, either by feeding crops to stock on the land or by applying stable and kraal manure. A ton of fresh stable manure, consisting of cattle and horse excrements, together with more or less straw, etc., con- tains as a rough average about 10 pounds nitrogen, 5 pounds, phosphoric oxide, and 10 pounds potash. Partly decomposed kraal manure is generally richer if kept under proper con- ditions. In feeding crops to stock, under average conditions, it is said that about one-third of the total dry matter of the feed, about three-fourths of the total nitrogen and phosphoric oxide, and practically all the potash, are recovered in the excrements, liquid and sohd. On this basis, for every ton of dry feed con- sumed, rather more than a ton of fresh manure is produced, assuming the latter to contain 75 per cent, water. To summarise the foregoing, the principal facts that should be noted, and made use of in regard to the mainten- ance of fertility, are as follow : — {a) The beneficial effects of the rotation of crops as opposed to the single crop system. (b) That most South African soils are deficient in humus, and in many cases present cropping methods are causing further rapid depletion of the soil's supply, resulting in nitro- gen deficiency, poor mechanical condition, and decreased availability of other plant foods. Provision must be made for maintaining the humus supply, as already described. (c) That proper maintenance of the humus supply will in large part, and under best conditions, wholly maintain a sufficiency of nitrogen in the soil. In no other way can nitrogen be maintained so economically. The nitrogen alone in one ton of average kraal or stable manure, at current market prices, is worth over ten shillings. {d) That practically all South African soils are deficient in phosphoric oxide. Therefore, regular and adequate applica- tions of commercial phosphatic fertilisers, such as super- phosphate bone dust or basic slag, are absolutely essential. 52 CHAPTER IV (e) That the supply of potash is rarely deficient, and that the use of commercial potash fertilisers for common farm crops is seldom profitable. Stable or kraal manure contains a fair amount of potash, so that if much of this material is used for soil improvement considerable quantities of potash will be brought into the soil in an extremely economical form. Old sheep kraal manure is exceptionally rich in potash. Com- mercial forms of potash may frequently be used with profit for a few special crops, such as tobacco and potatoes. (/) That the supply of lime as a plant food is practically never deficient, but in the case of " acid " soils applications of lime, in the form of finely-ground limestone, are probably desirable. Before incurring heavy expense by the purchase of large quantities of lime, the farmer is advised to test the effect appearance. 7. Lustre or polish 10 8. Sulci (space between rows) 5 9. Freedom froan diseased symp- toms 5 ^ 10. Length of ear 5 ^ 11. Shape of grain 10 12. Length of grain 5 Particularly as 13. Shape of ear and straightness ^ regards breed of rows 10 characteristics. 14. Uniformity of cobs and grain 10 15. Colour of grain and cob ... 5 J Total 100 Brief RxrL.\NATioN of Points. (1) Indentation. — Various indentatiilons characterise the different dent breeds. However, an excessively chaffy condi- tion indicates imperfect maturity often due to disease. MAIZE. 99 (2) Kernel Composition. — This also varies with the variety, but within the variety preference should be given to those showing the most horny starch, as this tends to give maize of a high protein content and of high weight per bushel; and, moreover, white starchy seed is often the result of disease and poor ripening. (3) Kernel Characteristics. — Healthy, well-matured ears usually have thick, plump, bright and clean kernels, having well-developed embryos. (4) Shank Attachments. — Hitherto these have been trimmed away for show purposes. They should be left, however, as found when broken off the plant. Ears with shanks diseased, shown by a pink or brown discolouration and in a shredded condition (i.e., the parenchymatous cells of the pith have become disintegrated by the action of disease organisms and the fibrovacular bundles are left intact, giving a sringy appearance) should be discriminated against, as well as those having shanks too slender or too thick. (5) Tips of Ears. — The tips should show no signs of discolouration or injury from weather, insects, birds, etc., as these are usually those not well covered by the husks. Well filled tips, while due largely to favourable weather at time of fertilisation, should be favoured. (6) Butts or Ears. — These should not be unduly " swollen " or compressed, and should also be well filled, a condition governed to a great extent by weather conditions. (7) Lustre or Polish. — Vigour, healthy development and complete maturity are almost invariably associated with a bright, polished, oily appearance. Those lacking lustre and having a dull appearance should be scored against, since they too often give rise to poor, unproductive and diseased plants. 8. Sulci. — Within the variety the space between the rows should not be too wide nor too narrow. It is possible that too great a width may indicate low yielding strains, while grain excessively crowded may be found on cobs lacking vigour. (9) Freedom, from Diseased Symptoms. — Discolouration near the tip of the kernel may denote disease, and any other evidence of disease should "be discriminated against. A brownish discolouration near the tip of large white fiat kernels is often found in maize which has matured late in the season when the night temperatures are apt to be very low. This discolouration is probably due to the condensation of moisture 100 CHAPTER VI by the low temperatures with a subsequent oxidation of the testa during the comparatively high temperatures of the day. This should be taken as evidence of disease. (10) Length of Ears. — This will depend on the variety and climatic conditions. Within limits, having regard to the fact that length is directly correlated with late maturity, it should conform to the requirements of the breed and the area in which it is grown. (11) Shape of Grain. — This should be typical of the variety. (12) Length of Grain. — Depth of grain should be fav- oured. It must be borne in mind, though, that often the deeper the grain the later the maturity, and that variation in environ- ment may cause variation in depth. (13) Shape of Ears and Straightness of Rows. — These should be typical of the variety ; cylindrical ears are to be given preference, although high yielding strains are often found to have tapering ears. A too pronounced tapering gives grain lacking in uniformity, since those near the tip are con- siderably shallower than those near the butt. Crooked rows are undesirable, since the greater the fault in this respect the more irregular the kernels; and, moreover, repeated selection for crookedness has shown crookedness to be of a cumulative character, in that the rows may be eventually lost. (14) Uniformity of Cobs and Grain. — Uniformity is an indication of purity. A lack of uniformity in shape, colour, size and general aj^pearance should be severely cut. (15) Colour of Grain and Cob. — This should be typical of the breed. Variation of colour in the grain may indicate crossing, in which case the hybrid kernels may often be found at the extremities of the ear. Ears showing cross-fertilisation should not be used for seed. General Kemarks on Show Maize. — While the value of shows, particularly in a rapidly-developing country, serves as a rallying point to those interested, and gives an impetus to the industry as a whole, the value of the exhibits for seed may often bo doubtful, since the production of show maize may be accomplished by special treatment, liberal manuring, wide spacing, etc., of what may be relatively poor maize. How- ever, on the whole, show maize may be taken as being above the average, and farmers taking the trouble to exhibit are usually those who practise some form of useful selection. Fancy points, having no direct bearing on utilitv, are too MAIZE. 101 often over-emphasised to the detriment of inherent produc- tive qualities. DeaUng with this, Hays and Garber comment as follov^^s : — " Maize shows have accompHshed much in teach- ing growers the characteristics of various standard varieties. They have, however, over-emphasised the value of ear type as a means of maize improvement. Much work has been carried on with the view of determining the relation between various ear and plant characters and ability to give high yields. In general, no single character has been found to be so closely related with yielding ability as to be of much value from the standpoint of selection. This seems reasonable when we realise that yield is the final result of many growth characters. Too close uniformity of type probably tends to reduce yield, for we have learned that self-fertilisation in maize causes a marked decrease in growth vigour as compared w^ith cross-fertilisation." Extensive experiments conducted in Ohio, in which the yields from long and short ears, cylindrical and tapering ears, ears having bare and filled tips, etc., were compared, showed no appreciable gain in favour of any of these characters. The specialised maize-breeder, working chiefly at experi- mental stations, pursues more technical methods to improve maize, and usually resorts to the ear-to-row method of selection or combines the best qualities of various, strains through hybridisation. The Eae-to-"Row Method. — The first step to take is to label the most desirable parent plants in the field to be selected from. Tt is wise to select at least 100 plants; care being taken to select rohust plants growing in full competition with other plants and having no environmental advantage. When mature the desirable ears are selected, of which pro- bably 75 per cent, will be discarded. Each ear is labelled and described. Half of the grain from each is now planted in separate rows, the remnant being carefully stored until the following season. A test of this nature must be made in duplicate, haviui^ every fifth row as a check. Beffinning with a check, every fifth row throughout the test will he planted as a check. Each series will thus contain 32 rows and the whole test 64 rows. Eor the checks use good seed taken from the shelled jrrain of the general crop. Rows twenty-two yards loner with the plants every eisrhteen inches will be found a useful lencrth. Care must be taken to have the same number of plants in each row. 102 CHAPTEB VI When mature the rows are harvested separately, the good and bad ears separated and weighed. If in both series an ear is high yielding, it may be taken for granted, with reasonable certainty, that the parent ear was of a productive strain. The highest yielding ears are then taken and planted in an isolated field, and from this field seed is obtained for the general crop the succeeding year. Cross-breeding takes place in the breeding plot ; fresh blood being introduced from various sources into the ear-row test each year, and, while the breeding may be narrowed down by the introduction of ears from other breeders into the ear-row test of the sixth and subsequent years, a suffi- ciently heterozygotic condition is established to counteract any possibility of a loss of vigour due to the in-brceding of norm- ally cross-fertilised plants. The ear-to-row series need not be isolated, but the fields used to increase the seed from the productive ears should be kept apart from other maize. The ear-to-row test should be continued, each year ears being selected from other reliable breeders of the same variety in the same locality. As a means of isolating high yielding strains the ear-to-row test is very much discredited by some, chiefly because it is said that the results are masked by the xenial effect caused by crossing. Nevertheless, in varieties where no continued selection has been practised, this method will undoubtedly assist in procuring some of the most pro- ductive strains. Shull's Pure-Line Method in Maize-Breeding. — Be- fore devising the above method, Shull's previous experiments had led him to conclude, firstly, " that in an ordinary field of maize the individuals are generally very complex hybrids ; secondly, that the deterioration which takes place as a result of self-fertilisation is due to the gradual reduction of the strain to a homozygous condition, and, thirdly, that the object, of the maize-breeder should not be to find the best pure- line, but to find and maintain the best hybrid combination." The process may be considered under two heads : (i) Find- ing the best pure-lines, and (ii) the practical use of the pure-lines in the production of seed maize. (i) In finding the best pure-lines it will be necessary to make as many self-fertilisations as practicable, and to continue these year after year until the homozygous state is nearly or quite attained. Then all possible crosses are to be made among these different pure strains, and the Fl plants coming MAIZE. 103 from each such cross are to be grown in Ihe form of an ear-to- row test ; each row being the product of a different cross. These cross-bred rows are then studied with regard to yield and the possession of other desirable qualities. (ii) After having found the right pair of pure strains for the attainment of any desired results in the way of yield and quality the method of producing seed maize for the general crop is a very simple, though somewhat costly, process. Two isolated plots will be necessary, plots 1 and 2. In plot 1 will be grown year after year only that pure strain which investigation has proved to be the best mother- strain for the attainment of the desired end. Thus, if it has been found that cross C.X.H. gives the desired result, plot 1 will be occupied by strain C. This will require no attention from the breeder's point of view, except that any exceptionally vigorous or aberrant individuals should be eliminated, as such plants may be safely assumed to be the result of foreign pollinations. In plot 2, strain C and strain H are to be planted in alternate rows, and all of strain C is to be detasseled at the appropriate time. All the grain gathered from the detasseled rows will be seed maize for the general field crop, and that gathered from the tasseled rows will be pure-bred ; strain H to be used again the following yeax in the same way. Here again in pure strain H all exceptionally vigorous or aben-ant individuals should be discarded as being probably due to the entrance of foreign pollen. Maize Composition. — Composition of the various parts of the maize plant. Water — free basis (15). Analysis. Extract. Per cent. Per cent. Per cent. Per cent. Per cent. Part. No. of Ash. Protein. Fibre. N. Free. Fat. Fodder . 35 4-7 7-8 24-7 60-1 2-8 Leaves . 17 7-9 8-6 30-6 51-0 1-9 Husks . ir, 3-5 5-0 32*2 57-9 1-4 Stalks . 15 3-6 5-9 34-8 64-1 1-6 Stover . 60 5-7 6-4 33-0 53-2 1-7 Grain . 208 1-7 11-7 2-4 78-1 61 From the above it will be seen that the nutritive ratio of the most concentrated part, the grain, is approximately 104 CHAPTER VI 1 :10'5, while those of the other parts are considerably wider. The necessity therefore of supplementing a maize ration with material of a higher protein content is apparent. " In well-developed maize," says Montgomery, " planted at proper distances for maximum yield, the weight of shelled maize will be almost equal to the weight of stalk. Increasing the rate of planting has very little effect on the composition of either grain or stalk, but as the proportion of stalk to grain increases, it is evident that the analysis of the whole plant will show a decreased percentage of protein and fat, and an increased percentage of fibre. The total protein per acre will increase. Silage from very thickly planted maize will not be so rich in percentage of protein and fat, but the total yield per acre will -be greater." Experienced farmers have long maintained that yellow flint maize has a higher nutritive value than dent maize, and while the ordinary chemical analysis has shown little difference in favour of the former, recent investigations in the United States of America ascribe the higher feeding value to the superior vitamine content found in the flint types. Any account of the maize composition, however brief, would be incomplete without some reference to the research work done in selecting high and low protein maize at Illinois University.'* The maize kernel was mechanically divided into tip-cap, hulls, horny glutenous part (aleurone layer), horny starchy, white starchy part and embryo. Analyses of these parts from a number of kernels showed that those having a high protein content could be separated by inspection from those having a low protein content, and those containing a high percentage of oil could be separated from those having a low percentage of oil. Analysed, these parts showed that the increase in protein in high protein maize over that low in protein occurs almost entirely in the horny part of the kernel. 75 per cent, of the total ash and 80 to 84 per cent, of the oil are contained in the grain. Continued selection, guided by the analysis of these parts, eventually separated strains having the following widely- different composition : — MAIZE. 105 Protein. Oil Ash Carbos per cent. per cent. per cent. per cent. Low protein ears ... 6-71 4-21 1-37 87-71 High protein ears . 14-44 4-93 1-56 79-OG Low oil ears 9-98 2-52 1-44 86-07 High oil ears . 11-31 7-00 1-55 80-14 It is interesting to note that eventually a marked positive correlation was found to exist between the high protein ears and those having a high percentage of oil. Uses of the Maize Crop. — While in the United States of America most of the grain produced is fed to live stock, in South Africa the greater part of the grain not exported is used for human consumption. It is eaten in a great many forms by Europeans and is the staple food of the South African natives. As has been stated, its use as silage is rapidly increasing, and the stover forms an important part of the winter feed for stock. Numerous other uses are made of the crop — the husks are used for making matting, hats, filling for mattresses and horse- collars ; the stalks and pith provide cellulose and maize-pith packing ; the cobs are used in making tobacco pipes and for fuel, and from the grain, starch, glucose, dextrine, maize oil, glycerine, sugar and alcohol are obtained. Pop-maize is used in the manufacture of confectionery; green sweet, flint, dent, and flour ears are used roasted or boiled in most South African households ; maize meal is made into porridge ; in America into johnny-cake, and during the late war a certain amount was used with wheat flour in making bread. For a detailed discus- sion on the uses of this crop the reader is advised to consult " Maize : Its History, Cultivation, Handling and Uses," by J. Burtt-Davy, as well as his articles, " Maize as a Raw Material for Manufacture," published in Vol. V. of the South African Journal of Industries. Maize Pests. — (1) Insects. — Those most commonly and often causing considerable damage are : — Cut-worms (Agrotis and Euxoa spp.), Sta.lk-borer (Bussiola fusca), Ear-worm (Chloridea obsolete). Army Worm (Laphygma exempta), Weevil (Calandra oryzse), Angoumois Grain Moth (Gelechia cerealella), and Locusts (Locustana pordalina). Cut-worms are best controlled by winter ploughing and 106 CHAPTER VI, by poisoned bait scattered over the infested land; the stalk- borer by growing catch-crops early in the season, winter ploughing, and by the American plan of harvesting; and the granary pests by fumigation with carbon bisulphide. (i2) Other Animals. — There are a number of animals which cause damage to this crop, such as : Baboons, Cape monkey, ground squin-els, porcupines ; crows, springhares, partridges and pheasants. Systematic shooting and poisoning aj-e fairly effective measures in dealing with these. (3) Diseases. — The most common diseases are : Brown Rust of Maize (Puccinia maydis), alternate host Oxalis corniculata. Although bad in certain seasons and in limited localities, it has not proved a serious menace so far. Certain varieties are more resistant than others, e.g., vigorous growing varieties, like Potchefstroom Pearl, etc. Maize Smut or Brand (Sorosporium reilianum), common in all parts of the world where maize is grown. Prevention should be aimed at. Use new seed from smut-free fields, and where possible burn all affected maize early, and avoid using fresh manure from animals fed with affected plants. Ear-rot of Maize (Diplodea zeae), very common in South Africa, and is the source of a disease causing paralysis in cattle. The American plan of harvesting should be followed to guard against this disease, which is most common on fallen cobs. Rotate crops, and where possible burn old affected plants or bury very deeply by ploughing. Leaf Scorch or Maize Blight (Helminthosporium turci- cum) occurs, but is of little economic importance. Weeds. — Perennial. — Cynodon dactylon (Quick), Cy- perus rotundus, or escultentus (Vintjes), Convolvulus arvensis (Bindweed), and Rumex acetosella (Sheeps' Sorrel). Annuals. — Amaranthus paniculatus (Pigweed), Bidens pilosa and leucantha (Black-jack), the grasses Chloris virgata and Panicum la3vifolium. Datura stramonium and tatula (Stinkblaar), Physalis minima (Wild Gooseberry), Tagetes minuta (Khaki-bos). Parasitic. — Striga lutea (Witchwecd or Rooibloom) is con- trolled by growing a hos.t plant such as Sudan or teff grasses, which can be harvested when the parasite is in bloom ; after this the land is ploughed before the weed has a chance to seed. This is probably one of the worst weed pests of the maize crop in the Union, MAIZE. 107 REFERENCES: ^ " Productive Farm Crops," by E. G. Montgomery. * " The Production of Foodstuffs for Live Stock in South Africa," by H. D. Leppan. * " Report on Maize-Growing Competition," by G. J. Bosman. ■• " Maize," by J. Burtt-Davy. * " Southern Field Crops," by Duggar. « " The Corn Crop " by E. G. Montgomery. ' Bulletin 57, U.S.A. Department of Agriculture, by Sturtevant. " " Journal of Heredity," April, 1918. ' " Agricultural Meteorology," by J. W. Smith. •» Results of Manurial E.xperiments on Maize, Union Department of Agriculture, Bulletin 3, 1914. "Maine Agricultural Experiments, Bulletin 17:4. '- Grain Elevators for Union of South Africa, U.G. 3, Parliamentary Report, 1919. '^ Report of Parliamentary Commission on Grain Elevators, U.G. 38, 1919. '* " American Breeders' Association," Volume 5, Pages 951-959. ^' U.S.A. Department of Agriculture— Office-Experimentalist Station^ Bulletin 77. ^* " The Structure of the Corn Kernel and the Composition of its. Different Parts." Bulletin No. 87, University of Illinois, 1913. *' " Breeding Crop Plants." — Hays &nd Garber. CHAPTEE VII SORGHUMS History. — Piper says sorghums were erown in China in •2200 B.C. Whether this is correct or not, it is certain that sorghums were grown for grain in very ancient times. Their culture hy Europeans is of comparatively recent date. In 1853, Wray collected sixteen varieties in Natal for the United States Government, which were the first to be imported into the United States. To-day sorghums play a very important part in the agri- culture of the dry Western States of America, and the success of these crops there has stimulated their culture in other parts of the world, including South Africa. Production. — The acreage devoted to kaffir corn in the Union in 1911 was 166,597, while in 1918 it had risen to 233,105 acres. No figures are available of the world's pro- duction. In the United States the crop is limited to the dry semi-arid States of Kansas, Oklahoma, Colorado, etc. The following figures show the increasing importance of sorghums in those States, and the area cultivated in India. Kansas. 1901. 1913. India. Kaffir ... 618,816 acres. 1,403,731 acres. 30,000,000 acres. Milo ... 5,988 ,, 229,534 ,, The sorghums, being more drought resistant, arc gradu- ally taking the place of maize in all parts of the world where the moisture is not sufficient for the latter. They would be grown more extensively in South Africa were it not for the depredations of birds. Origin, Description, and Classification. — The pro- genitor of those having rootstocks is supposed to be Andro- pogan halepensis, while that of the chief agricultural sorghums is held to be Andropocion sorghum. The cultivated sorghums are thought to have originated in Africa. Tunis and Sudan grasses are annuals, and because these do not have root- stocks and cross readily with kaffir corn and Milo they are considered to be closely allied to the original wild form. 108 SORGHUMS. 109 The panicle varies considerably from the small, compact type in which the rachis is almost as long as the panicle to the Broom-corn type, in which the rachis is only one-fifth the length of the branches. ^eeds. — The shape of the seed varies from round in the Kaffir, Ivowhang, and Shallu groups, to somewhat pear-shaped in certain of the sweet sorghums, fairly flattened in Milo, and decidedly flat in the Durras. The astringency of the dark coated varieties is due to the presence of small amounts of tannin. The distribution of horny starch and starchy endos- perm somewhat resembles maize, in that the soft starch is surrounded by horny starch.' The United States Department of Agriculture has analysed the kafiir kernel on similar lines to those employed in the analysis of the maize kernel at Illinois University. Except for the high ether extract found in the bran of kaffir the analyses are very similar, viz. ; — Comparison of Kaffir and Maize Separations. Ether Material. Kernel. Ash. Extract Protein. Carbos. per cent. per cent. per cent. per cent. per cent. Maize Hulls 7-39 0-79 0-89 3-96 94-36 Kaffir Bran 61 2-0 6-8 4^8 86-4 Horny endos perm — Maize 55-59 •44 1-15 11 ^85 86-56 Kaffir 48-9 •3 -7 14-5 84-5 Starchy endo sperm — Maize 25-49 •26 •24 7-84 91-66 Kaffir 35-0 •3 •8 11^66 87-3 Germ — Maize 11-53 9-90 34-84 19-80 35-46 Kaffir 10-0 13-20 31-5 19-3 36-0 Distribution OF Constituents Ether Crude Crude N.F. Material. Whole Kaffi r. Ash. Extract. Protein. Fibre. Extract. Germ 10-0 77-9 75-2 15-5 19-1 4-1 Bran G-1 7-2 9-9 2-3 49-7 55 Starchy Endosperm 35-0 6-2 6-7 28-4 14-1 38-4 Horny Endosperm 48-9 8-7 8-2 53-8 17-1 520 110 CHAPTER VII " The results of this study show that corresponding parts of the kaffir and maize kernels resemble each other in com- position and appearance, and lead us to believe that if kaffir were handled in a manner similar to that used in the prepara- tion of maize products, kaffir products might be substituted for the corresponding maize products." The colour of the seed varies considerably with the varie- ties, white, black, red, and yellow being the most common colours. Ste7tis. — The stems vary from 4 to 15 feet, and from | to 2 inches in thickness. They may be juicy or dry ; in the former the juice is easily extracted by crushing or chewing — the difference in actual water content is small. Those having very juicy pith are the canes or forage sorghums, the grain sorghums having a pith less juicy and not sweet. Tillers. — Appear as in maize, being governed largely by spacing, temperature, soil fertility, variety and soil moisture. Branches. — With very thin planting, branching may occur beginning from latent ])uds, that of the topmost node being the one always to develop first. Because the heads on these branches mature later than those on the main branch, they are undesirable, and planting should be thick enough to inhibit this tendency. Leaves. — These are short and broad, coarse in texture, roll together in an erect fashion, which apparently protects them from hot winds and protracted drought. The most drought-resistant kinds are the most scanty-leaved. Roots. — These feed more in the surface soil than maize. The most outstanding characteristic of the sorghums is their drought resistance, which is attributed to the resistance of the leaves to dry, hot, and windy weather; the non- saccharine sorghums being more resistant than the forage or saccharine kinds. Their capacity to remain almost dormant during drought, and then to continue growth immediately with the improvement of the weather, enables the crop to with- stand drought better than maize, which, if once severely checked, will never entirely recover. In the early stages, sorghums are slower growing than maize. Sorghums are perfect-flowered, and are usually self- fertilised, although cross-fertilisation is very common, and crosses between the most widely differing types occur quite frequently. SORGHUMS. Ill Sorghum Types, based on Economic Uses. (1) Saccharine sorghums. (2) Non-saccharine sorghums. (3) Broom-corns. (4) Forage sorghums : — Sudan, Tunis, Johnson. (1) Saccharine Sorghums (Soet Ricts). — Those having an abundant sweet juice. Previously cultivated for syrup, but now principally as a forage plant and for silage. — I. Cane or Sorgo. (2) Non-Saccharine Sorghums. (a) Pith contains scanty juice, which varies from slightly sweet in some varieties to semi-acid in others. Grown principally for the grain, but has also forage value.— II. Kafi&r. III. Milo. (b) Pith Dry. (i.) Grown principally for the grain and forage. II. Kaffir. VI. Durra. "IV. ShaJlu. V. Kowliang. VII. Feterita. (ii.) Grown for the panicle (brush) ; little value as forage. — VII. Broom-corn. In South Africa, the principal varieties grown belong almost entirely to the Kaffir type, namely : BlackhuU Kaffir Com, WhitehuU Kaffir Corn (both these have white seeds), and Ked Kaffir Corn. Varieties from all the other groups have been grown from seed distributed by the Government, but have not been gener- ally adopted. The local demand is chiefly for the natives on the mines, who prefer the white-seeded varieties. Saccharine Sorghums. — These are usually low yielders of grain, and are grown principally for forage or for silage. They are generally tall, slender, leafy, with pyriform seeds. Early Amber, Orange and Sumac, Planter's Friend, Sugar Drip, are varieties which have been tried in the Union and have given good results. Sudan Grass and Tunis Grass are also forage sorghums, usually looked upon as grasses. Non-Saccharine Sorghums. — Comparatively heavy seed- yielding, and stocky in growth. In the Kaffir Group the heads are erect, long, and cylindrical obovate seeds. In the Durra Group the inflorescence is thick, compact, ovate and pendant large flattened seeds (Yellow Milo, Durra and Feterita). Broom-Corn Group. — The varieties in this group have wide-spreading panicles. 112 CHAPTER VII General Xotes on Varieties. — Of the saccharine sor- ghums, Early Amber Cane is the earliest and one of the most prolific yielders of forage. Sudan Grass is dealt with fully in the chapter on Grasses. Of the non-saccharine sorghums Milo and Kowliang, Feterita, and Dwarf Negari, are the earliest, the latter matur- ing in some localities from 85 to 95 days. Milo is one of the most drought-resistant and heaviest seed-yielding varieties. It is immune from kernel and head smut, and is three weeks earlier than Kaffir. It is of very little use as forage. Most milos have recurved necks. Kaffir. — Is later in maturing ; a heavy seed yielder, and fairly valuable for forage or ensilage. The grain is smaller than the Milos or Durras, but is less liable to shatter. Shallu. — Somewhat resembles Broom-corn in having open panicles. It is grown chiefly for grain, but has a fair forage value. Feterita. — Matures about a week earlier than Milo ; is a very heavy yielder of seed, but has a too strong tendency to branch . Durras. — Are better adapted for grain production than the Kaffirs, but are not so well suited for forage purposes. They have large flat kernels, and are nearly all goose-necked. BOTANICAL CLASSIFICATION. (6) Order. — Graminece. Tribe. — Andropogonece. Genus. — Andropogan. Species. — A. Sorghum var. vulgare. Ball has suggested the following classification as a key to the principal groups of sorghum : — I. — Pith juicy. (A) Juice abundant and very sweet. (1) Internodes elongated ; sheaths scarcely over- lapping ; leaves 12 — 15 (except in Amber varieties) ; spikelets elliptic-oval to obovate, 2"5 to 3'5 mm. wide ; seeds, reddish-brown. — I. Sorgo. (B) Juice scanty, slightly sweet to sub-acid. (1) Internodes short ; sheaths strongly overlapping ; leaves 12 — 15, peduncles erect; panicles cylindrical; spikelets obovate ; 3 to 4 mm. wide ; lemmas awn- less. — II. Kaffir. SORGHUMS. 113 (2) Internodes medium ; sheaths scarcely over- lapping ; leaves 8 — 11 ; peduncles mostly inclined ; often recurved ; panicles ovate ; spikelets broadly obovate ; 4'5 to 6 m.m. wide; lemmas awned. — YIl. Milo. II.— Pith dry. (A) Panicle lax, 2'5-7 dm. long; peduncles erect; spike- lets elliptic-oval or obovate, 2'5 to 3'5 mm. wide; lemmas awned. (1) Panicle 4-7 dm. long; rachis less than one-fifth as long as the panicle. (a) Panicle umbelliform, the branches greatly elongated, the tips drooping; seeds reddish, in- cluded.— III. Broom-corn. (2) Panicle 2'5-4 dm. long; rachis more than two- thirds as long as the panicle. (a) Panicle conical, the branches strongly droop- ing ; glumes at maturity spreading involute ; seeds white, brown, or somewhat buff. — IV. Shallu. (b) Panicle oval or obovate, the branches spread- ing; glumes at maturity appressed, not involute; seeds white, brown or reddish. — V. Kowliang. (B) Panicle compact, l-2'5 dm. long; peduncles erect or recurved ; rachis more than two-thirds as long as the panicle. (1) Spikelets elliptic, oval or obovate, 2" 5 to 3' 5 mm. wide ; lemmas awned. — V. Kowliang. (2) Spikelets broadly obovate; 4-5 to 6 mm. wide. (a) Glumes grey or greenish ; not wrinkled : densely pubescent ; lemmas awned or awnless ; seeds strongly flattened. — VI. Durra. (6) Glumes deep brown or black, transversely wrinkled, thinly pubescent; lemmas awned; seeds slightly flattened.— VII. Milo. CLiiiATE. — Sorghums do best in a rather dry, hot climate, but do not do too well at high altitudes where the nights are cool. While maize and sorghums both prefer climates having plenty of sunshine and warmth, they differ in that the de- veloped sorghums of to-day prefer less humid conditions than maize. No doubt some of the tall-growing tropical forms require very humid conditions for their growth, and the broom- 114 CHAPTER VII corns as well as some of the saccharine sorghums do well under conditions preferred by maize rather than those must suitable for the non-saccharine kinds. In the United States of America the average annual rainfall for the Grain Sorghum belt is about 20 inches, varying in different parts from 15 to 25 inches, the majority of which falls in the growing season, and the evapora- tion is from 35 to 55 inches. They are extremely sensitive to frosts, but their water requirement is less than that of maize. Soils. — In general, soils suitable for maize are suitable for sorghums, although good forage crops are grown on soils too poor for maize. They are supposed to be much more alkali-resistant than maize. Being comparatively surface feeders, they have the reputation of being very exhaustive of soil fertility. In reality this is not so, since suitable rotations will maintain the yield. In semi-arid parts the soils are usually vei-y poor in humus, consequently to increase the water-holding and water- absorbing capacity of the soil rotations should be judiciously planned to increase or maintain the humus content when economically possible. Soil Preparation. — This is very similar to that required by maize, but as the seedlings are less vigorous than those of maize the surface should be reduced to a finer tilth. Deep ploughing in sorghum areas is not always advisable, as it may result in excessive desiccation of the soil and subsoil, which is in most cases harmful. The object should be to keep the soil free from weeds, and in a receptive condition for rain. Ploughing and leaving the ground rough until just before planting is sufficient. Just previous to planting the ground should be worked down into a moderately fine tilth. On some soils, though, deep ploughing has proved necessary. Very sandy soils are common in the sorghum areas, and on these care should be exercised to prevent blowing. Humus is particularly important, and every means of incorporating it economically should be resorted to. If free from weeds, the soil should be left undisturbed as long as possible. On these soils American experience indicates that listing is preferable to ploughing, as the soil is disturbed less. Seed. — This weighs 64 to 62 pounds per bushel. When a variety has been found suitable to a particular part that variety should be adhered to, and selection should be made from the desirable plants before the whole crop is har- vested. As the seed of sorghums grown under uncertain con- SORGHUMS. 115 ditions may vary considerably in size, care should be taken not to discard a variety on that account. This may necessitate the adjustment of the planting plates accordingly, in order to obtain a correct spacing. EoTATiONS. — While it may pay a maize farmer to have a third or fourth of his land down to cowpeas, it may be un- profitable for a farmer growing grain sorghums to do the same unless his farming is also largely devoted to stock-farming. Green-manuring in arid parts, while extremely important, has been found to be very costly. The yield per acre is small, con- sequently extensive methods are more profitable. However, if cowpeas or similar crops can be fed on or off the land, and the manure returned to the soil, as a policy of permanent agricul- ture it will pay to do so. On very sandv soils the effect of green-manuring in binding the soil will often compensate the farmer for his extra expenditure. Fertilisers should be em- ployed very cautiously and not until experimented with on a small scale. These soils are often extremely poor in phos- phates and, where deficient, small dressings of 100 to 200 pounds of superphosphate per acre may pay. Phosphorus has a tendency to promote vigorous root-growth, and in doing so enables the plant to feed over wider areas. Thus a better use of the available moisture and plant food is afforded. In com- parison with most soils, those in sorghum areas are compara- tively rich in plant food, and the necessity for applying fertilisers is not so urgent as in more humid parts. Planting. Date of Planting. — Their early growth is very tardy, particularly in cool weather, consequently they are usually planted somewhat later than maize. In South Africa the date of planting is usually governed by the seasonal rainfall. The Kaffir corns may be planted from the latter part of October to the end of December, while Milo, Feterita, and Kowliang Negari may be planted up to the middle of January. Sor- ghums for forage or ensilage may be sown up to the latter part of January. Late sown sorghums are often badly attacked by aphids. As in all crops, the rate of planting depends on the fer- tility of the soil, the climatic conditions, the vitality of the seed, and the purpose for which the crop is grown. For forage, planting must be much thicker than for grain or silage. For grain, the rows should be 3 to 3 feet 6 inches 116 CHAPTER VII apart, and the plants 4 to 8 inches in the rows. This requires from 1^ to 5 pounds of seed. For forage, though, the rows may be 2 feet 6 inches and 3 inches in the row. If broadcasted for forage, about 20 to 30 pounds of seed is required. Failures in obtaining good stands are frequently caused by planting too deeply. Planting must be shallower than for maize, about one to two inches, according to the condition and type of soil, seems to be the best depth. The best implement for planting is the maize planter, most of w^hich are now supplied with suitable plates. If these are not obtainable, the holes in the ordinary planter plates should be tilled with lead, and new holes of desirable size bored through these lead fillings. Before use, the planter should always be adjusted and tested on a hard road or suit- able place, to see that the correct distances of planting have been arranged. After Cultivation. — Harrow once the plants are well rooted. After this the ordinaiy maize cultivation should follow to break light shower crusts and to keep the land free of weeds. Harvesting. Time of Harvesting.— T/ze Grain Sorghums should be harvested when fully matured. If, however, the crop is to be used for ensilage, harvesting should take place in the soft dough stage, as ripe seeds in silage are apt to pass through animals undigested. The best method is to shock the whole plant, as in maize ; when cured and thoroughly dried the heads are taken off and run through the ordinary grain-thresher. Some farmers in South Africa send boys dowm the rows with clippers, to slip off the heads into bags. These heads are then thrown into heaps or stored ready for threshing. The seed is very liable to overheat, particularly when slightly immature or damp. If stored in bins or tanks it must be carefully watched, and if any evidence of overheating is shown, the seed must be thoroughly ventilated by shovelling, etc. A good average yield in South Africa is about 15 to 25 bushels. For Silage. — Extensive experiments in Kansas have shown sorghum ensilage to be practically equal to maize silage from a feeding point of view. The saccharine sorghums do not seem quite so valuable as kaffir. On account of their succu- lency they should be cut at a later stage of maturity (when the SORGHUMS. 117 seed is comparatively hard), otherwise sour silage may result. The average yield is from six to eight tons per acre. For Forage. — Sowing is usually heavy. 20 to 30 pounds broadcasted or drilled with seed-drills. If planted in rows with a maize planter about 15 pounds per acre are required. The latter method is to be preferred in South Africa. For forage purposes saccharine sorghums should be used. It is somewhat difficult to cure ; bundles should be placed in small stooks at first, and left until thoroughly cured before being stacked. If broadcasted, it may be treated as ordinary hay, care being taken that the hay is fairly dry before being cocked. The average yield is two to five tons per acre. Comparisons between Sorghums and Maize. — Sorghums will produce good crops more reliably than maize in parts where maize, owing to a lack of moisture, is uncertain. Good practice is adopted in parts of the Lichtenburg District, where the annual rainfall is about 22 inches, but of an erratic nature, in planting half the land to maize and half to sorghums. In the years when maize fails as a grain crop it can be used for silage, and the sorghums can then be relied upon to produce a fair yield of grain. This is the practice adopted over large parts of the Western States of America, bordering on the Maize Belt. In parts of the Union having less than 20 inches of rain, sorghums should undoubtedly supplant maize altogether. Comparison of Yields of Maize and Kaffir at Stillwater, Okla. Crop. 1909. 1910. 1911. 1912. 1913. Average Kaffir 34-0 19-0 45'5 48-0 28-0 34-9 bushels. Maize 25 000 OO'O 1-5 I'O I'O do. The superiority of the yield of the sorghum at this semi- arid station is largely due to the fact that sorghums can remain dormant during periods of drought, while maize is practically ruined when badly checked in growth. The composition of the grain has been shown to be prac- tically the same as that of maize, the digestibility being slightly lower. The storage and harvesting of the sorghums is more difficult than maize. Sorghums, if checked in grow^th during dry, bright weather, develop poison to a dangerous degree, and pasturing them should be done with caution. When frosted, the after- math is said to be particularly dangerous. If fed, when cut 118 CHAPTER VII and wilted, the toxin largely disappears. No cases have been found of prussic-acid poisoning of stock fed on sorghum silage. Uses. — In South Africa, the grain is used chiefly as food for the natives. In America, it is used mainly as food for stock, being ground before being fed, but its use as a human food is increasing. In America and Europe, the seed is used extensively as a poultry feed. Its use as silage and forage has been shown. The sac- charine sorghums are used for forage, and seem well adapted for that purpose, as several cuttings can be obtained in one season. In humid parts, Ontario, etc., the sorghums are also used for pasturage, either alone or mixed with millets or oats. In Asia their uses are most varied, the seed being used as human food and the stems for thatching, building, mats, fuel, rafts, etc. The cultivation of the saccharine sorghums was really begun in America originally for syrup making, 1,200 pounds of juice being obtained from one ton of cane. Syrup is still made, but the practice is rapidly decreasing. It was also grown for this purpose by the Boer pioneers in the early days. Broom Corn. — The cultural methods are similar to those described for the grain sorghums. The brush should be bright green, with a short rachis, long, flexible and tough. The dis- tance in rows, two to four inches, is much closer than for milo or kafifir. The crop is harvested quite green, or soon after the full bloom stage. The heads are threshed a few days after harvesting, after which the brushes are cured and dried and then baled. The seed may be used as a stock food, but on account of its immaturity and the adhering glumes, is not nearly as valuable as that of the grain sorghums. Several varieties have been grown in the Union, and fac- tories at different centres for the manufacture of brooms have been in operation for many years. Probably owing to the labour entailed, and lack of experience, the manufacturers have found great difficulty in getting farmers to go in for broom-corn culture, and consequently the brush is imported from America. At present the demand for brush exceeds the supply, prices varying from £40 to £80 per ton. Improvement. — Probably no crop in South Africa has been so neglected. Little or no selection has taken place, varieties have not been properly identified or appreciated, and their place as a dry-land farming crop has not been sufiiciently recog- nised (except by natives). , SORGHUMS. 119 ■' There are certain definite characteristics that are re- quired in the grain sorghums. Chief among these are even height, early maturity, dwarf stature, well shaped and fairly compact heads, erect heads, freedom from stooling and branch- ing, good exsertion of the head from the upper leaf sheath."* The head to row method is the best means of seeing the merits of the respective strains. As they cross easily, heads must be bagged before flowers open. While leafiness with total yield should be aimed at in the forage sorghums, in the true grain-sorghums the yield of seed, drought resistance, and early maturity, seem to be correlated with an absence of leafiness. SCOEE CAED FOE GEAIN SOEGHUMS. Head Samples. Points. Uniformity of Heads and Kernels . . . Shape of Heads Size of Heads ... Arrangement of Spikelets ... Shape of Kernels Size of Kernels ... Colour of Kernels and Glumes Freedom from Shattering ... Exsertion Market Condition Total Grain Samples. Uniformity in Size and Colour ... Shape and Size of Kernels Market Condition Weight per Bushel Total Value. 20 10 5 20 5 5 5 5 10 15 100 20 20 35 25 100 Score. Notes on Score Card (Head Exhibits). Uniformity. — The heads should be similar in size, shape and colour. Shape and Size. — True to standard of perfection for the variety. 120 CHAPTER VII Arrangement of Spikelets. — The spikelets and seed-stems should be close together in the common types of the grain sorghums, except in Shallu and White Kowliang. A compact head indicates a high percentage of grain. The spikelets should be close together, pedicles short, and the branches of the panicle thickly covered with seed, both on the inside and out- side. Low yielding or light heads have few or no grains on the inside of the branches, and on the lo\ver half of the branches. The joints of the main spikes or seed-stems should be short. Short-jointed main stems, five or more joints in number, indicate a large number of rows of spikelets, giving a high-yielding head. The head must not be too compact, how- ever, as drying will not take place easily. Shape and Size of Kernels. — Should be true to variety. Colour of Kernels. — Must conform to type. Freedom from Shattering. — Shallu, Feterita, and Jerusa- lem Corn, are usually bad in this respect. The heads should be shaken, and if many kernels drop out the head should be discriminated against. Exsertion. — The head should be free of the boot or upper leaf sheaths. If the lower spikelets are not filled out or are mouldy, poor exsertion is indicated, and such heads are in- ferior for seed purposes. Market Condition. — There should be no sign of decay, dis- ease (smut), or immaturity. Grain Exhibits. Uniformity in Size and Colour. — Uniformity in these de- notes trueness to type, careful selection, and evenness of maturity, and also grain that will store well. Shape and Size of Kernels. — These should be true to type, and in the variety the larger the grain the better. Market Condition. — The sample should be free from dirt, mustiness, foreign matter and disease. Weight per Bushel. — No official standard has been set ; 56 pounds is the usual weight for Kaffir ; some varieties are lighter.' Preference should be given to the heavier strains in the variety. Shelling Pereentage. — Kaffir and Milo heads should give 77 to 84 per cent, of grain respectively. Plate V -ILOS SHEWING CUTTER AND BLOWER Plate VI naj H HH B9 ^Bh ^^HF \ t '■ ,^W ^H ^^^n tVPIH F^^^^^^B H.^pi^ H ^^H sHIil m Ej!'?*'^! fl TYPES OF SORGHUMS (LEFT TO RIGHT) ; SHALLU. AV}UTE KAFFIR CORN. FETERITA, WHITE MILO, WHITE DURRA, EARLY AMBER SACCHARINE SORGHUM AND BROOM CORN. Plate VII HEADS OF KAFFIR-CORN (LEFT TO RIGHT) : HEAD SHOWINCx POOR EXSERTION (UPPER LEAF SHEATH REMOVED) ; HEAD SHOWING POOR EXSERTION; HEAD SHOWING GOOD EXSERTION. IE VI IT PLANT OF FETERITA, SHOWING UNDESIRABLE BRANCHING DUE TO TOO WIDE SPACING IN THE ROW. SORGHUMS. 121 Diseases and Pests. — (1) Kernel Smut {Sphacelotheca sorghi). In Kernel Smut only the individual grains are affected, the head being only slightly changed in appearance. The disease can be controlled by the use of formalin, (2) Head Smut {Sphacelotheca reiliana). — Head Smut re- sembles maize smut to some extent ; the entire head is destroyed. On exsertion, the head is found to be composed of a mass of spores covered with a whitish membrane. The ontogeny of the organism is not properly understood, and no satisfactory treatment has been found. Care should be taken to get uninfected seed. Eed Spot or Blight (Bacillus sorghi). — Eed spots appear on stems and leaves, causing the latter to die prematurely. Seldom serious ; certain strains are more resistant than others. Sorghum Midge (Diplosis sorghicola) .—E^s, laid in flower and ovary destroyed by larvae. No treatment known ; somewhat rare. Early varieties in America are less susceptible to severe injury. Eooi Bloom iStriga lutea). — Is parasitic, and should be treated as in maize. Sorghum Aphis {Heuning Dow). — This insect has proved serious to late-sown sorghums, especially in the Lowveld. REFERENCES: 1 " Forage Plants and Their Culture."— Piper. 2 " Botany of Crop Plants." — Robbins. 3 " The Corn Crops."— Montgomery. •» " The Grain Sorghums."— Bulletin No. 102. Okla. ^ " Better Grain Sorghum Crops."— U.S.D. of Agri. Bulletin 448. « " The History and Distribution of Sorghum."— U.S.D. of Agri. Bulletin 175. " " The Uses of Grain Sorghum."— U.S.D. of Agri. Bulletin 686. « " Kafir."- Bulletin 198, Kansas. ' " Milo as a Dry-Land Crop."— U.S.D. of Agri. Bulletin 322. » " Kafir as a Grain Crop."— U.S.D. of Agri. Bulletin 552. ' " Saccharine Sorghums for Forage." — U.S.D. of Agri. Bulletin 246. - " The Smuts of Sorghum."— U.S.D. of Agri. Circular Bulletin. ' " Trials with Millets and Sorghums for Grain and Hay in S. Dakota." —Bulletin 135, S. Dakota. '• " Broom-Corn Culture." — Texas New Series No. 2. * " Sorghum Crops for Silage." — Circular No. 28, Kansas. 8 United States Department of Agriculture No. 634, 1918. ■CHAPTER VIII. THE POTATO History. — The natural habitat lies in the highlands of Chile and Peru, whence (at the time of the Spanish conquest of Peru in 1533-1535) it was taken to Spain. It was grown in Europe for some time before its introduction from Virginia into England by Sir V^'^alter Raleigh, who, in 1585 or 1586, cultivated potatoes on his estate in Cork, Ireland. It rapidly became one of the world's principal articles of diet, and, on account of its intimate association with the history of the latter country, it is often spoken of as the Irish Potato. The following are some interesting figures of production in bushels : Average total Average yield production per acre for 1911-13. 1904-13. Germany .. 1,698,826,000 200- 7 European Russia .. 1,258,120,333 106- 4 Austria-Hungary 642,149,000 134-35 France 499,523,666 130- 2 United States ... 348,303,000 96- 5 United Kingdom 259,482,666 210- 0 About 90 per cent, of the total production is grown in Europe, The average Australian and African production for 1908-12 was -26 per cent, and -09 per cent., respectively, of the world's production. The potato crop's average position for 1908-1912 among the worid's crops is given by Gilbert as follows — viz. :* — Potatoes Maize Wheat Oats Rice Rye Barley Million tons. 161- 0 128- 38 106- 0 65 6 55- 6 57- 0 33- 41 122 THE POTATO. 123 During 1917-18 the Union of South Africa planted 110,185 acres, obtaining 234,538,000 pounds, or an average of about one ton per acre. The census for 1911 showed an average of one and a half tons per acre. Under intelligent management and in favourable localities, yields of four and a half tons (60 bags) are not uncommon. The table which follows, compiled from the 1919-20 agri- cultural census returns, shows the total number of bags of potatoes growing in each Province of the Union. For purposes of comparison the total production in bags of the two chief cereal crops is also given : — Crops. Cape. Natal. Transvaal. O.F.S. Total. Potatoes.. .. Wheat .. .. Maize .. .. 291,000 1,118,500 502,800 134,920 4,560 1,442,540 521,870 285,050 3,923,000 303,130 130,610 3,500,740 1,250,920 1,538,720 9,369,080 From the above it is evident that the potato ranks only third in importance among the crops produced in the Union, and it is likely to remain so, as our present market for this crop is confined to the local trade, which is limited. Below is given the two highest producing districts in each Province and the quantity produced by each of them : — Quantity produced Province. District. in bags. Cape Humansdorp 20,880 Stellenbosch 18,240 Natal Newcastle 24,455 Estcourt 17,220 O.F.S. Thaba 'Nchu 87,380 Ladybrand 47,550 Transvaal Bethal 140,790 Middelburg 47,550 The bulk of this production is obtained without irrigation. The crop is well suited to those areas of high altitude in the regions of summer rainfall. There is no doubt that large areas of suitable land for the cultivation of potatoes are still available in the Transvaal and Orange Free State. In these Provinces the production is rapidly increasing. 124 CHAPTER VIII Description and Classification. — Of the large number of Solaniim species only six are tuber-bearing, and of these S. tuberosum (the common or Irish potato) is the only one of agricultural importance to-day. The roots are fibrous, the tubers being formed at the ends of rhizomes. " When grow- ing under natural conditions the tubers are relatively small, close to the surface of the soil or may be upon it. The pro- duction of small green tubers on the haulm in the axils of the leaves of the potato is not infrequent, and affords an inter- esting proof of the true morphological nature of the under- ground shoots and tubers. This phenomenon follows injury to the phloem in the lower part of the stem, which prevents the downward flow of the elaborated sap." Seeds are produced on the upright stems in smooth berries, perfectly globose and under an inch in diameter. The varieties of cultivated potatoes to-day vary in the formation of berries, and in some cases, owing to the production of non-viable pollen and general incompatability, and also adverse climatic conditions, some strains rarely form berries. In some cases even the formation of inflorescences is suppressed. Self -fertilisation rarely, if ever, occurs. When sown the seeds produce plants bearing small tubers the first year, which reach normal size in about three years. Since potatoes are normally propagated vegeta- tively their purity is comparatively constant. Unlike the artichoke tubers, that of the potato never bears roots. The view is held by some that the formation of tubers is associated with the presence of certain fungi, and that in reality the potato tuber is a gall produced by a micro-organism. Potatoes are classified' into agricultural groups according to the colour and shape of the tuber, sprouts and flowers. Shape of Tuber. — Eound, oblong, and long, either flattened or round. Those tapering at one end are said to be spindled when compared with uniform potatoes. Colour of Skin. — This may be white, cream-white, flesh- coloured, pink, rose, red, bluish, mottled and russet brown. Colour of Sprouts. — " The colour of sprouts is very important in determining the main groups of varieties. The colour is determined by germinating the potato in the dark, and as soon as the sprouts appear, they are examined usually with a magnifying glass. The sprout is tipped with minute scales or leaflets, which may be either coloured or white. Also the base of sprouts may be either coloured or white. The usual colours are white, cream-white, pink rose, rose-lilac, magenta, lilac, violet, or deep violet." — jNTontgomery.* THE POTATO. 125 Colour of Flowers. — These may be white, rose, rose- lilac, rose-purple, purple and violet. The depth and number of eyes vary considerably in the different strains. Those having shallow and few eyes are most sought after. Classification According to Maturity. — The following are the principal varieties grown in the Union — viz. : — Early , about 90 days : Epicure, Early Rose and Early King. Medium — 90 to 110 days : Flourball, Factor, Arran Chief and Arran Comrade. Late — 110 to 130 days : Up-to-date, Five Towers and Scottish Triumph. New varieties, as the old sorts become less popular, are constantlv being introduced, e.g., Kerr's Pink, King Edward VIL, etc. Structure and Composition of the Tuber. — Four distinct zones are found in the tuber. " The outer skin is the coloured portion and may be completely separated from the part underneath. The cortical or fibro-vascular layer lies next, and is easily distinguished by the separating line of vascular bundles. In the interior the inner medullary layer appears like an undeveloped stem branching out towards the eyes." Composition of the different zones of the potato tuber : — Total nitrogenous Variety. Zone. Water. Starch. matter. Geante Cortical 72-74 21-14 1-91 Out. Med. 74- S3 19-78 1-88 In. Med. 81-72 12-30 2-14 Czarine Cortical 72-9-2 22-45 1-84 Out. Med. 78-87 15-64 2-17 In. Med. 84-48 10-50 2-11 Sancisse Cortical 78-72 14-38 2-22 Out. Med. 79-12 13-47 2-39 In. Med. 80-73 12-31 2-62 The water and nitrogen contents increase from the outer to the inner zones, while the starch content decreases." The average composition of the potato is very similar to that of the soft wheats, and is composed as follows : — 126 The CHAPTER VIII Per cent. Water . 75 to 80 Starch . 16 to 20 Protein 2 to 3 Ash 1 Fat . Trace. Fibre . Trace. Epidermis . 2-5 Cortical layer 8-5 Inner medullaiy 1 ' and 89 Outer medullary ) The starch granule is characteristically marked with eccentric rings, and is relatively large in size. Good potatoes may be judged with the aid of the follow- ing score-card of the New York State Potato Association : — Poini /S to be considered — Conformity Conformity Varietal type. Market demands. (1) Uniformity 20 20 (2) Blemishes and diseases ... 15 20 (3) Shape 15 15 (4) Size 10 15 (5) Quality of the flesh 10 10 (6) Depth and frequency of eyes 15 10 (7) Colour and texture of skin 15 10 100 100 Total ... 200 The requirements for " seed " tubers must, naturally, vary somewhat from those required in marketing, and in a score-card of this nature the combined requirements are well met. (1) Uniformity. — The tubers should be uniform in general appearance, e.g., shape, size, colour, etc. (2) Blemishes and Diseases. — There should be no evi- dence of disease, insect depredations or injurj^ due to rough handhng. THE POTATO. 1^ (3) and (4) Shape and Size. — Should be typical of the variety. On the whole, those varieties in best demand are those oval-flat or round-flat in shape, and medium in size. A spherical tuber if sufficiently large to be desirable is so thick that in cooking the exterior is likely to become overdone before the interior is properly cooked. (5) Quality of Flesh. — Must be typical of the variety, fine-textured, light in colour, free from excess moisture and from hollow or dark spots. East^ says : " The cortical layer, below the first few layers of cells, which are removed with the skin, shows a remarkably larger amount of starch in the cells than does the internal medullary layer. The starch content of the external medullary layer is also greater than that of the internal. The grains of starch in the cortical and external medullary layers, besides existing in greater numbers per cell, are generally of larger average size. The paucity of starch in the internal medullary layer causes the cells to be only partially filled with the cooked starch, and the cell walls are scarcely ever ruptured. In the cortical layer, on the other hand, the amount of starch is such that in the swelling due to cooking the cells are filled completely, and many of them ruptured, causing the mealy appearance so much desired by the consumer. " It is quite evident, then, that potatoes having, so far as possible, a homogenous flesh, and containing as large an amount as possible of cortical and outer medullary layers in proportion to inner medullary layers, should be of the finest qua.lity," It must be remembered that the quality may vary accord- ing to the manner of use in the different countries. English- speaking people prefer a potato when boiled to be soft and mealy, while the French, who usually fry their potatoes in deep fat, prefer one which, when boiled, gives a relatively firm and soggy appearance. (6) Depth and Frequency of Eyes. — Trueness to variety is necessary. The market demands few and shallow eyes in order that wastage due to peeling may be at a minimum. (7) Colour and Texture of Skin. — This should be typical of the breed — the market wants a thin, tough, smooth or netted skin. Climate. — For optimum growth cool and moist conditions are required. In South Africa conditions corresponding to those of the plant's natural habitat have proved the most 128 CHAPTER VIII suitable, consequently those districts in high altitudes, of a cool and moist climate, are fast becoming the leading potato districts e.g., Thaba 'iS^chu and Bethal. The requirements of climate are largely met by the time of planting, hence the main crop in the Union is often planted in November or December, so that the time of tuber development is towards the cooler part of summer and in the autumn. The early crop (grown only under irrigation) is planted in August and lifted in November before the hotter summer weather commences. Soil and Manorial Eequirements. Soil. — The ideal soil appears to be a well-drained, deep, friable, rich loam, containing an abundant supply of well- decayed organic matter. The crop requires a light, porous, open soil, for the following reasons : — (1) The root system is weak and small compared with that of a plant like maize, and is especially weak in penetrat- ing heavy soils. (2) The crop is easier to plant, cultivate, and to dig. (3) The tubers develop more freely, are smoother and more regular in shape. (4) Fertilisers and manures are more effective. Eelatively heavy soils in which large quantities of organic matter have been incorporated , provided they are well drained . may be, contrary to popular belief, very productive. Potatoes follow a green manure better than most crops, and do well on virgin land, provided a fine seed-bed is pre- pared. It is a crop well suited to follow on land after lucerne is ploughed down. It is never a profitable crop on poor soils, as, being a surface feeder and short-lived, it requires a soil in a high state of productivity. On average farm soils the following manurial applications have been found to give good results — viz., 10 to 12 tons well-rotted kraal manure, and ;in addition 300 lbs. super- phosphate or 400 lbs. bone dust ; the manure should be ]->loughed under before planting and in sufficient time to ensure thorough decomposition. The superphosphate, or bone dust, should be applied in the rows at the time of planting. Where no kraal manure is available, 200 lbs. guano, with 200 lbs. of bone dust, and 100 lbs. of superphosphate, in all 500-600 lbs. per acre, have given satisfactory results. THE POTATO. 129 The potato is a potash-loving plant ; but in most South African soils this element of plant food is usually found in sufficient quantities to supply the needs of the crop. The experience at the different experiment stations in the Union has been that a combination of kraal manure with mineral fertilisers has given much better results than either alone. The organic matter seems essential for successful potato propagation. It will be noted from the following experiments* that complete mineral fertilisers (Plot 16) gave no better result than eight tons of kraal manure per acre by itself. The best yield was obtained from 400 lbs. superphosphate, 400 lbs. of wood ash , and 4 tons kraal manure ; and the next best with kraal manure and superphosphate alone. It would be as well when wood ash is not available to use in its place 80-150 lbs. of sulphate of potash. Co-operative fertiliser experiments at Zeerust (1920- 1921) :— Plot No. Fertiliser used Rate per acre Yield per acre lbs. bags. 1. Superphosphate 400 lbs. 2,420 16-1 2. do. 600 lbs. 2,783 18-3 3. Kraal manure 4 tons 2,783 18-4 4. Control . No treatment 1,936 12-9 5. Kraal manure 8 tons 3,388 22-5 6. Supeii^hosphate Wood ash 400 lbs. 400 lbs. 2,904 19-3 7. Superphosphate Kraal manure 400 lbs. 4 tons 4,598 30-6 8. Control . No treatment 1 ,936 12-9 9. Superphosphate 400 lbs. Wood ash 400 lbs. 5,082 33-8 Kraal manure 4 tons 10. Wood ash Kraal manure 400 lbs. 4 tons 3,872 25-8 11. Wood ash 600 lbs. 2,420 16-1 12. Control . No treatment 1,815 121 13. Wood ash 400 lbs. 1,694 11-2 14. Sodium nitrate 100 lbs. 2,178 14-5 15. Sulphate of potash . 100 lbs. 2,178 14-5 16. Superphosphate 400 lbs. Sulphate of potash . 100 lbs. 3,388 22-5 Nitrate of soda 100 lbs. 17. Control . No treatment 1,875^ 12-5 130 CHAPTER VIII Lime or manures giving an alkaline reaction should not be used immediately before planting, as soil conditions will then favour the development of Scab (Actinomyces chromo- genus). Cultural Methods. — The potato responds to good soil treatment better than most field crops. Initial ploughing should be deep and thorough as the plant requires a deep, mellow and moist seed-bed. Just prior to planting, the field should be either cross-ploughed, disced or cultivated in order to loosen the soil and to establish a fine tilth. Planting. — There are at least two methods in vogue in the Union, namely, the " ridge " and the " flat " system. In the former system the tubers are planted in furrows or drills, previously drawn with a ridging plough after the seed- bed has been prepared. In the latter method they are planted between the second and third share or disc of a three-furrow plough, or else in the second furrow of a two-furrow plough, followed by a single-furrow plough to cover up the seed. Most of the seed is planted by hand, as machines have proved unsatisfactory so far. The sets are placed either slightly to the right in the furrow where the trek animals cannot trample on them, or else thev are dropped in the furrow between the hind oxen and the plough, or, better still, from the seat of the plough between the second and third share or disc of a three-furrow plough. The " ridge " system is recommended under irrigation and where the crop is likely to experience a wet season. In the former case ridging facilitates water-leading, and prevents encrustation of the soil next to the plant, and in the second it affords drainage. On dry-lands the " flat " or level system will, in most cases, prove to be the most useful and profitable one, as it will assist in conserving moisture. Quantity per Acre. — The quantity required will vary with the size of the sets and the spacing. About 1,000 lbs. (6 to 7 bags) of tubers the size of a hen's egg (2 to 2J ozs. in weight) is the average amount planted. The " seed " should be sonnd, free from disease and sprouted, or at least showing signs of germination. If a moist condition of the soil is assured large tubers may be cut to about the above weight to economise in " seed." They should be cut to have, as far as possible, two to three eyes per piece, and the cut surfaces should be covered with THE POTATO. 131 gypsum or calcium carbonate (ordinary lime) or clean wood- ash, forming a crust over the surface. The object of this is to prevent undue desiccation. Cut seed should be planted soon after cutting, and should not be left exposed or planted in dry ground. Experiments at Grootvlei and Tweespruit, O.F.S. (1906-1908),' showed a marked increase of whole over- cut tubers, when the same spacing was used in planting. Seed Tubers. — Where seed has been held dormant it is good practice to place the seed in a light warm place to sprout. This should be done some time before planting — a uniform standard is obtained in this way, because potatoes of retarded germination can be discarded, and only those planted which have started to sprout. The shoots should not be allowed to grow too long. The great difficulty ip_^outh Africa at present is to prociryseecT olJlie proper maturity at the difFercnt times of ^janfing, as it is almost impossible to secure_places of low enough temperature to ensure~~<^CSTInant" tubers. Seed lifted during the winter months start sprouting with the advent of warm spring weather, and as this is not used for the main crop until November and December, it is found hard to retard the growth until then. With the prevailing high temperatures of September and October this is by no means easy of accomplishment. Some farmers are successful in doing the lifting as late as possible, about the end of July (in some places in October) and then placing them in mounds. These mounds are made by having the tubers in long piles covered with a thick layer of grass, which, in turn, is covered with about a foot of soil, care being taken to chose a cool, well-drained site, and to provide good ventilation by having holes through the covering, which are usually kept fairly open with bundles of grass. In this method the pile should be examined from time to time to see that the tubers are not decaying. In storage the temperature should be kept as low as possible (in South Africa), the humidity of the air in the stor- age place should not be high nor too dry, and the supply of air (oxygen) should be limited. Where small amounts of seed are handled greening is possiblv the best method. Here the tubers are placed one layer thick in shallow crates, which are placed in a well-venti- lated situation in strong light. In this manner they may be kept sound for several months while they produce short. 132 CHAPTER VITI stubby sprouts and turn a slight greenish colour. Very few sprouts are broken off during planting. Immature tubers produce more vigorous plants than those fully matured, hence it is the custom in some countries to dig tubers before maturity, or to allow the crop to ripen pre- maturely by withholding water ; or to plant late and to allow the crop to be frosted before maturity. Tubers not fully matured are easily bruised in handling, and the germination is apt to be slow and irregular. However, with careful hand- ling, storage, and if sprouted as described, excellent crops are obtained, as will be seen from the following experiment conducted at the Ontario Agricultural College : — Seed obtained from planting of: Average of six varieties. May 31st 192-37 bushels per acre*.^ June 14th 194-80 ,, June 28th 201-84 July 12th 2i9-46 ,, The farmer, under irrigation growing both early and main crops, experiences difficulty in getting the seed lifted in November and December to sprout in time for January plant- ing. While germination may be hastened by placing the tubers in a warm, moist situation (a covering of moistened stable manure is often of assistance), this method is not always successful. Potatoes are grown in the Low Veld — e.g., Koe- does Eiver and Barberton — in time to be lifted in October and ready for the main crop planting in December and January, and these could be used for seed by the farmers on the High Veld. Rotations. — As previously stated, potatoes follow green manure better than most crops, as the comparatively loose soil produced is suited to their growth. Below are some suggested rotations : — (1) Without Irrigation — dry lands. 1st year — Maize. 2nd year — Maize, with an application of phosphates. 3rd year — Cowpeas (kaffir beans), ploughed under. 4th year — Potatoes, manured as previously recom- mended. If an excess of nitrogen is indicated by too much top growth at the expense of tuber formation, then the potatoes THE POTATO. 133 should receive only a light phosphatic dressing without the kraal manure, or the crop of cowpeas might be eliminated in the rotation or used for hay. (2) Under Irrigation — two-year rotation. 1st year — Winter crop : wheat with a dressing of phosphates. Summer crop : cowpeas ploughed under. 2nd year — Winter crop : wheat, with a dressing of phosphates. Summer crop : potatoes with kraal manure. (3) Seven to nine years' rotation : lucerne, followed by potatoes, followed by wheat, having a dressing of phosphates; land then to be re-sown to lucerne. Planting. — Under irrigation, two crops are grown in one year, the spring-planted crop for the summer and autumn ; and the summer-planted crop for the winter and spring markets. The early crop is planted from June to September accord- ing to the climatic conditions of the locality ; in the Low Veld, where litle frost is experienced, the crop is planted in June and July; in the High Veld and Middle Veld in August, or as soon as the danger of late frosts is over. For the summer crop, planting takes place in December and January. Without irrigation the date of planting will vary with the commencement of the seasonal rains for the locality and the condition of the stored seed tubers, usually from September to January. For the spring planting the early varieties are used, and medium and late varieties for the main crop. The tendency in South Africa is to plant much too closely. The rows should be three to three and one-half feet apart, and the tubers 12 to 18 inches in the rows. In moist climates, or under irrigation, on rich soils, a much closer spacing is used. The tubers should be planted four to six inches below the surface, depending on the nature of the soil. Planting machines, under South African conditions of labour, have not proved satisfactory, and the crop is mostly put in by hand. After Cultivation.— Before the plants appear above ground, it is often necessary and advisable to harrow the field to destroy weed growth and to break any crusts which 134 CHAPTER VIII might have formed. This may be repeated while the plants are still small and unlikely to be injured. Cultivation to keep the ground loose and to destroy weeds should start soon after- wards, getting shallower as the roots spread, and must be continued until after flowering. Under irrigation, and to a less marked extent on dry lands, the crop should now be ridged (earthed up) to check tubermoth injury, and to prevent the soil cracking, which is undesirable, for when exposed to light the tubers assume a greenish colour. Potatoes respond to heavy irrigation, provided this is well distributed, better than any field crop. Experience has shown that where possible water should not be applied during the extreme heat of the day, as this practice seems to predispose the plants to disease. Wide fluctuations in the soil moisture should be avoided, as malformed tubers are common if the growth is interrupted. Heavy irrigation should be avoided also during the early growth of the crop. Harvesting. — The main crop should be dug when thoroughly mature, i.e., when the skin is firm, the tops have dried and the tubers separate easily from the rhizomes. Tuber development and starch storage are most rapid during the last month of growth, and continue as long as the tops are green. In areas of dry winters, having relatively low tempera- tures, the potatoes are often left in the soil and are lifted only when required. On the High Veld they may be left in the soil until August. The early crop is often harvested before maturity, as the loss in yield is counter-balanced by the hisfh price obtained for new potatoes. The early crop seldom yields as heavily as the main crop. If the vines are frosted before maturity the tubers should be left in the ground for some time to enable the skin tb harden. The crop is usually lifted by hand, double mouldboard plough, or potato digger. The latter implement is coming into more general usage, although some difficulty has been found in South Africa in hard, dry ground to get the digger to dig deeply enough. In the Union, potatoes are sold in bags 153 pounds gross. Unfortunately, £frading is little practised. Medium-sized potatoes are preferred to those very large, and no discrimina- tion with regard to colour is shown. Prices fluctuate from a THE POTATO. 135 few shillings to a few pounds per bag, depending chiefly on the season. The best prices are obtained from July to October. Uses. — Apart from their use as human food and to a certain degree as stock food, potatoes are used in the produc- tion of starch, alcohol, glucose and syrup. Potato flour is used largely in European countries as an ingredient in flour for bread-making. Potato Improvement. — No discussion on this topic would be complete without a survey of the chief factors in- volved in the question of degeneracy in potatoes. It is the experience of capable growers, in some localities widely differing from the natural habitat of the potato, e.g., of high temperatures, of low rainfall, and often at low altitudes, that the importation of seed tubers is necessary because of the depreciated productivity of old strains. There are many factors contributing to this state of affairs ; chief among these are : — (1) The prevailing method of selecting the culls and small tubers to be used for " seed " purposes. — In this method hills of low productivity, and, although not apparent, often diseased, receive disproportionate representation in the suc- ceeding crop, consequently there is a constant tendency for the crop to decrease in yield — colloquially " to run out." To counteract this tendency, hill-selection should be practised to obtain the high yielding biotypes (strains). The procedure is to select healthy and vigorous plants in the growing crop, and when dug to take the most productive and desirable hills for propagation in a breeding plot. This is multiplied by suc- ceeding plantings until sufficient seed tubers from these high yielding hills are secured to plant the main crop. Hill-selec- tion should always continue from the main crop, and the breeding and multiplying plots maintained. That the yielding capacity of the hills in the same variety differ widely is shown in the following experiments — viz. : Ontario Agricultural College. Davies Warrior Selections. No. 5 Average for three years. 243-4 bushels per acre 2 216-3 „ 1 190-8 ,, 8 136-2 ,, 136 CHAI 'TER VIII Average for five years in Cornell University. bushels per acre. Low-yielding strain 67 High-yielding strain 251 Low-yielding strain 100 High-yielding strain 203 Low-yielding strain 80 High-yielding strain 171 3. (2) Degeneracy is attributed by Stewart and East to be due largely to diseases earned in the tuber. The organisms have not been isolated, and some of these diseases may be physiological, exhibiting themselves under unfavourable con- ditions. Typical of these are those disorders knowns as Mozaic Disease, Spindling Sprout and Curly Leaf. (3) It has been suggested that the continual asexual pro- pagation may be the cause of this degeneracy, since the vigour due to heterosis cannot manifest itself. East, however, main- tains that this view is unproven. There is no doubt, however, that this so-called degeneracy can be checked to some extent by hill selection. In localities well suited to that plant, the productivity is often maintained without recourse to any special form of selection. For instance, in Ontario, where the climate is favourable, Zavitz has grown five varieties in a variety test for 25 years without employing any method of selection ; these varieties have given a slight increase during the period of the trial. Emerson^ has shown that by mulching potatoes with about 4 to 6 inches of straw, and thus modifying the moisture and temperature of the soil, the productivity of varieties was maintained. In this method the field from which seed potatoes for the following year are to be obtained is mulched with straw after planting and no subsequent cultivation given. Improvement by hybridisation is slow, laborious and un- certain, and should be undertaken only by those having the time and means at their disposal. The chief obstacles are in getting crosses to take, and the time required to test the yielding capacity of the hybrids. Improved varieties have, however, been produced in this way. Mutations do occur, and if of some outstanding peculiarity are naturally selected by breeders and growers, and often good new varieties may be found. IE IX OfOO (QUALITY P008 PUAUITY A. POTATO OF GOOD QUALITY. SHOWING FEW AND SHALLOW EYES. B. POTATO OF POOR QUALITY. SHOWINC; XUJIEROTS DEEP-SET EYES AMOUNT OF INTERNAL ^tEDULLA .\ND CORTEX. Plate X n m \^^ m #■■■ '•> P(.)TA10ES IN RIDOES BEING CULTIVATED — POTCHEFSTROOM EXPERIMENTAL SJATION. (COURTESY UNION DEPARTMENT OF AGRICULTURE). LUCERNE PLANT SHEWING CROWN AND STRONG ROOTING SYSTEM. Plate XI LUWPEA ROOTS, SHOWING NODULES. '^■■rir ^ Wk*. * , ^ / 3k@ ^ffiSW^^M Is^ij^^SE '^:^i^S v^^v^tt ^^■^B^r jM^BWMlkdrv^^Bi SBfeH^^P^Tr*^ >^ ^MM^ IS 3HmB ■Mli Plate XII COWTEAS IX CENTRE WITH SOYBEANS ON LEFT AND KICHT. GREEN-SEEDIJi I'.ASrKoFT COTTON (I'OURTESY J. 1)U RrSTKNBrHC EXP. STATION. OOSTHL'IZEN). THE POTATO. 137 East says that yield is correlated with flat shape of tuber, number of haulms and length of growing season ; that round- flat tubers are richest in starch ; that a netted skin is usually associated with high quality ; and that heavy fruit production is associated with small tuber formation. In South Africa much might be done by the selection of heat-resistant strains. Diseases and Other Pests. — The potato is subject to numerous diseases, and as it is a widely-grown and important crop a considerable amount of attention has been focusscd on these by phytopathologists. Among the more important fungous and bacterial diseases in the Union are the following — viz., Bacterial Wilt, or Vrot-pootje (Bacillus solanacearmn) , Potato Scab (Actinomvces chromogenus), Early Blight (Macrosporium solani) Late Blight (Phytopthora infestans), Rhizoctonia Disease (Corticum vagum. var solani), Potato Rot (Nectria solani), and Wart Disease (SyncJiitrium endobioti- cum). The last-named has just lately been discovered by Mr. Puttick in Natal." Internal Brown Fleck is often met with in the Union, and at present the casual organism (if any) has not been isolated. Remedial Measures. — A good system of crop rotation is probably one of the best preventive measures, and the selec- tion of resistant strains is an avenue which might be further explored. It must be remembered that while a number of these diseases is limited to a specific host, others have alternate hosts — e.g., Macrosporium solani is also parasitic on Datura stramonium (Stinkblaar), consequently, weed control is of special importance. The use of disinfectants is growing in South Africa, and, no doubt, assists materially in the control of some of these diseases — e.g.. Scab. The potatoes are soaked in a formalin solution, one pint to 30 gallons of water, for one hour ; or two ounces of corrosive sublimate to 16 gal- lons of water for thi'ee hours. Seed tubers should never be cut before treating same for the prevention of scab. Spraying with fungicides to control vine diseases is at present uncommon in the Union, but may become more popular as farming becomes more intensive. Bordeaux Mix- ture, together with lead arsenate or Paris Green is chiefly used as a fungicide and insecticide. 138 CHAPTER VIII Insects and Other Pests. — The Cut-worm (Euxoa spp. and A gratis spp.), Tuber Moth (Phthorima;a operculella Lell), Millepeds and Eel-worm (Heterodera radicicola) cause con- siderable damage. Thorough cultivation, rotative cropping and the avoidance of soils poorly drained are preventive measures. Of the larger animals, the Porcupine and Wild- Boar prove serious pests in certain localities. POTATO REFERENCES: 1 " The Potato."— Gilbert. 2 U.S.A. Department of Agriculture Bulletin 176.— W. Stuart. * " Productive Farm Crops." — Montgomery. * Study of the Factors Influencing the Improvement of Potatoes." — ■ Illinois Bulletin 127.— East. ^ Annual Reports, Department of Agriculture, O.F.S. * Bulletin 146, University of Nebraska. ^ " Wart Disease of Potatoes." — Union Agricultural Journal, May, 1922. « " Potato Culture." — L. J. Bosman; Union Agricultural Journal, July, 1922. CHAPTEK IX LUCERNE History and Production. — Lucerne is probably the first plant to have been cultivated solely as a forage plant, and until recently was the only crop cultivated for this purpose by Asiatics. The natural habitat of Medicago sativa is along the coast of the Mediterranean, and, as far as is known, it was first culti- vated in this region. According to Pliny, it was brought from Media to Greece in the year 470 B.C. The United States of America imported it from Chili in 1854. It is now more extensively grown in North America, where it is known by its Arabic name, " alfalfa," than in any continent. It is one of the most important of the world's forage crops, being cultivated extensively in the United States of America, Canada, Eussia, South-Eastern Europe, France, Argentine, Australia, and South Africa. It was probably introduced into South Africa about 1860, and soon assumed an important position in South African agri- culture, particularly when, at a later date, the ostrich came into domestication. In fact, the chief impetus to its cultiva- tion was its generally recognised value as a feed for ostriches. However, to-day, its outstanding nutritive and high-yielding qualities have made it one of the most valued and widely grown of the hay crops in the country. It is limited in the Union to in'igable land of a suitable nature. It is safe to say that there is no other plant at present known which will furnish so much valuable forage for so long a term of years without re-seeding. A field at Glen Lynden, Bedford, planted forty years ago, was still producing good crops in 1921. Description and Classification. — Lucerne is a peren- nial legume, making its chief growth in summer, and attaining a height of 1^^ to 3 feet. When cut or grazed down, new stems arise from buds at the crown, and increase in number with 139 140 CHAPTER IX the age of the plant. It is characterised by its exceedingly deep and well-developed tap-root, which often penetrates to considerable depth, fifty feet and more. The more or less kidney-shaped seeds are borne in special racemes springing from the axils of the leaves. In the ordinary varieties under cultivation, purple is the characteristic colour of the flowers, and root-stocks are almost entirely absent. The places of origin of the medicagos are Europe and Asia. The genus Medicago contains a large number of species. Among the annuals the only ones of any agricultural import- ance, and then not in the Union, are the Burr Clovers, the chief of which is M. lupulina (Black Medick or Yellow Trefoil). Three species belonging to the perennials are of great agricultural value, namely, the H. sativa, M. falcata, and by hybridisation of these two, M. media. The plant M. sativa var. gaetula may prove of economic value because of its tendency to produce rhizomes. Medicago sativa. — Nearly all varieties in common culti- vation belong to this species. It is purple-flowered, has a very pronounced tap-root, and produces numerous upright stems. The plant in general is less bushy than in M. falcata. In M. falcata the seed is carried in spiral pods. Medicago falcata. — This species is yellow-flowered, with sickle-shaped pods. It also has numerous stems, but the plant is usually more decumbent and the stems are finer than those of sativa or media. It shows a tendency to have its crown par- tially buried, and a few plants have been found with rhizomes. The rooting system is more branched, and the tap-root less developed. It is found in the natural state in Siberia, and, consequently will stand extraordinary low killing tempera- tures, and is very drought resistant. It is not ordinarily high yielding. Medicago media. — This species has variegated flowers with spiral pods. In growth it resembles sativa, but is hardier and more resistant to drought and cold — qualities it owes to its falcata parent. Most varieties of supposedly the sativa type will be found to have some media characteristics. In cold, dry climates, varieties such as Grimms', Sand or Variegated, which are distinctly media, thrive better than varieties of sativa, such as Arabian or Peruvian. Medicago sativa var. gaetula. — This species was im- ported from Tunis to the United States. It is peculiar in having abundant rhizomes up to 3| feet in length. The hybrid LUCERNE. 141 from this sub-species and sativa gives promise of making excel- lent grazing lucernes, " giving a dense matted growth, a single plant covering a surface of several square feet, and pre- senting much the same general appearance as White Clover (T. repens)." Varieties. Provence or Common. — Is a variety imported from Provence, France. It is the best known and most commonly grown variety in the Union. A small percentage of the flowers are sometimes found to be variegated, but the great majority are purple. It is generally classed as belonging to the species sativa. The crowns are fairly close to the ground, and the stems are not quite so erect as in some of the other varieties — e.g., Peruvian. Hunter's Eiver and T.\mworth. — These are named after the districts where the seed is produced in Australia. There is practically no difference between these varieties, and both probably originated from seed imported from Provence, as they closely resemble the Provence variety. Under South African conditions, however, they are slightly earlier in start- ing their spring growth, and are said to be somewhat heavier yielding. Their cultivation is, in fact, becoming popular in the Union, and would become more so were it not that the imported seed costs several shillings per pound as opposed to less than a shilling for locally grown seed. Turkestan. — In appearance is very much like Provence, and in America has given good results in cold, semi-arid parts. In South Africa, however, it has not yielded as well as the latter variety, and is slower in growth. Arabian. — Is a very hairy variety, with large leaflets. It is of very rapid grcAvth and relatively short-lived. In Cali- fornia it has given up to twelve cuttings. However, by the third year the stand starts to become sparse, and is generally ploughed down by the fourth year. It is a very erect variety, with exposed crowns, easily injured by close grazing. Being more frost-resistant, it commences growth earlier than Provence. Peruvian. — Is similar to Arabian, and its marked pubes- cence gives it a 'bluish appearance. The crowns are very exposed, and the stems strikingly erect though somewhat coarse. The leaflets are large ; like Arabian, it has a long growing season and short life ; lacks hardiness , and is easily injured by grazing. 142 CHAPTER IX Chinese. — Introduced comparatively recently ; has not yet come into general use. A sativa variety, havmg somewhat hairy leaves. Vigorous, early and late growth, and appar- ently long lived. Excellent results are reported from the Grootfointein Agricultural School. Variegated, Sand or Grimms'. — Is undoubtedly a cross between sativa and falcata. The flowers are white, cream, yellow, bluish-green, smoky-green and purnle. It is slightly decumbent in habit, especially when widely spaced, but is more cold and drought resistant than Provence ; this is prob- ably due to its tendency to produce root-stocks. The crowns are fairly sunken in the ground. It has not been tried to any extent in South Africa, but may be of decided value, as it is well adapted for grazing as w^ell as for hay. Yellow, Sickle or Siberian {M. falcata). — Is very de- cumbent, crowns sunken in the ground; occasionally produces rhizomes. It is relatively low-yielding, and shatters its seed almost as soon as mature. It is very hardy, for w^hich reason it is extremely valuable as a parent in crosses. It is grown to a considerable extent in Siberia, but except in an experimental way has not been grown in the United States, Australia, or South Africa. Climate. — Lucerne is capable of withstanding great ex- tremes of temperature, and has been known to survive a tem- perature of 83 deg. F., as well as temperatures much higher than commonly occur in the Union. As far as cold is con- cerned, there are great differences in the resistance of many varieties, but the lowest temperatures in South Africa would not affect the vitality of any varieties. It is especially adapted to semi-arid climates. High humidity wath high temperatures are detrimental to its growth. Although lucerne will survive periods of excessive dryness, its water requirement is very hiffh ; hence if large yields are to be expected, the soil must be such that a large quantity of water is available for the growing plants. It there- fore responds more readily to, and will yield heavier crops under irrigation than under humid or dry-land farming conditions. Soil Conditions. — The heaviest yields of lucerne are obtained on deep, open, alluvial soils, well supplied with lime, and having a water table twelve to thirty feet below the sur- face. Hence along river banks, where irrigable soils of this nature are found, it is one of the most profitable of crops in the Union. LUCERNE. 143 The seedlings are very sensitive to alkali (brak), but if once established the plants will withstand a larger proportion of alkali salts. Acid (sour) soils are always poor lucerne soils, and it is questionable whether the crop can be grown on these soils profitably when liming has to be resorted to. If the water-table is within four feet of the surface, or if the subsoil is of a heavy, impervious character, or the soil shallow, the crop is rarely successful, as it is exceedingly sus- ceptible to a water-logged condition of the soil. Lucerne requires a productive soil. Eeinecke has found that this crop on land in the Transvaal, with a fair lime con- tent, gave a substantial profit when superphosphate (400 pounds per acre) or kraal manure (twelve tons per acre) was applied. The increases in yield over unmanured land, i.e., 3,672 pounds and 2,792 pounds, were valued at £5 16s. lid. and £2 4s. 3d. per acre, respectively. Bone meal was not so profitable, and the use of potash fertilisers showed no appre- ciable gain. Where kraal manure is employed it should be applied some time before sowing, so as to give it time to decompose thoroughly, and more especially to afford an opportunity of destroying the weeds, the seeds of which are carried in the manure, prior to sowing. It is often advisable either to apply the manure to the previous crop or to fallow the land previous to sowing. Top dressings of 200 pounds of superphosphate each season will prove profitable in most cases. This is best applied early in spring, when active growth has not started, and while the crop is being cultivated. Seed-Bed. — The land should be in as good a condition as possible, more care being required in its preparation than for the cereals. The early growth of the seedlings is largely de- voted to root-development, consequently they are poorly adapted to compete against weeds. The preceding crops, there fore, should be cleaning crops, i.e., cultivated crops. The seed- ling stage is the most susceptible phase of the crop. There- fore the soil should be compact and in a state of fine tilth. The preparation of the field should commence in ample time to allow the soil to settle and to get rid of weed growth. For successful lucerne growing it is essential that the land be carefully levelled, particularly with the object of econo- mising in water and labour. The fields should be divided into irrigation beds, with only a moderate fall of, if possible, about 144 CHAPTER IX six inches every one hundred yards. The beds, where neces- sary, should be terraced, and so far as possible should follow the contour of the land. Having regard to the slope, texture of the soil and volume of water available, to facilitate mowing, they should be as wide as possible. Usually they are made twenty to forty feet in width. The ground must be firm and, where possible, moist enough to ensure a fair start before the crop receives its first irrigation. To ensure a stand, in some cases irrigation must be resorted to, but to promote deep root grow^th the fields should be watered as little as possible during the early stages. Planting. — The best time to sow is in the autumn, before the first frosts, when the most active weed growth is over, and when the soil is kept moist by the late rains. If sown during March, April, or May, the risk of having the young crop destroyed by caterpillars is not so great as in spring, as the crop is well started before winter, and a number of summer weeds are killed by the first frosts. Planting in spring is sometimes successfully practised on land free from w^eeds. This crop is commonly sown broadcast, at the rate of 15 to 20 pounds per acre ; thicker seeding is recommended if the land is weedy. The seed is lightly covered with very light harrows, weeders, or a chain harrow. As the seed must not be placed deeper than an inch below the surface, those growers not in possession of any of these implements often resort to covering the seed by dragging branches across the field, or sow it on top of a moving harrow, or may even drive a flock of sheep to and fro to trample the seed into the soil. The use of a seeder is advisable, as a more even stand is secured and less seed is required, 10 to 15 pounds being used when a drill is employed. Lucerne is sometimes sown with oats, barley, or field peas, as a nurse crop. This, while a successful practice in more humid countries, is not generally recommended in South Africa, as the seedlings suffer from competition with the more rapid-growing plants of the nurse-crop. Seeds. — As lucerne is grown only on expensive land, and as preparation of the soil and the seed is costly, great care should be taken in the choice of seed. The following score- card may be used in judging the merits of seed : — LUCERNE. (1) Size and plumpness (2) Brightness, lustre or polish ... (3) Punty (4) Freedom from dark brown seeds Possible. 20 20 40 20 145 Total ... 100 (1) Size and Plumpness. — Some strains are smaller-seeded than others, while some are plumper. As in all seeds, how- ever, the plumper and the larger within the variety the better. Immature seed is often very flat and shrunken. (2) Brightness , Lustre or Polish. — This is the chief super- ficial means we have of distinguishing age and vigour in lucerne seed, and as it loses its vitality fairly rapidly after a few years, especially if poorly stored, it is important that the colour be bright. A dull appearance is easily detected, and invariably indicates age, severe weathering, or bad storage. The seed should have a high polish, be bright yellow in colour, and have an oily appearance. (3) Purity. — The presence and kind of weed seeds must be ascertained. In lucerne, this is of paramount importance, as weeds establish themselves before the crop has made much headway, on account of it having a relatively small growth during the first few^ months. Weeds are more objectionable in lucerne than in most crops, because the crop usually occu- pies the ground from five to seven years; consequently, inter- crop tillage can very seldom be resorted to. Moreover, weeds can be destroyed in the growing crop only with difficulty, and the value of the hay is much depreciated by their presence. Dodder (Cnssuta spp.) is the worst weed, and the only im- purity for which special laws have been provided to protect the South African grower. The seeds are somewhat smaller than lucerne seed, roundish in shape, and light to dark brown in colour. Weed seeds in lucerne are prevalent largely because some of the seeds of the worst weeds are about the same size and weight as lucerne seed, and consequently are hard to separate by winnowing or screening. Adulterants, particularly in European seed, are common, and are often difficult to distinguish. Seeds of Black Medick (M. lupulina) and Sweet Clover {Melilotus alba and leucantha) are those most commonly found. Sticks, stones, and dirt, naturally increase the price actually paid for seed. 146 CHAPTER IX (4) Freedom from Dark Brown Seed. — With excessive weathering, but particularly with age, the seed assumes a brown colour. The vitality of such seed is low, and often only a very small percentage is viable. If present in large quanti- ties, by no means uncommon, the quantity per acre used should be increased considerably. On the other hand, dark green colour is often a sign of immaturity, especially if the seeds have a tendency to be flat and shrunken as well. Inoculation. — Crop failures are sometimes due to the absence of certain bacteria (P. radicicola) in the soil. The plants grow only a few inches high, turn yellow, and then die. In land sown to lucerne for the first time, in which the plants behave in this way, all other conditions being favourable to its growth, and especially if no nodules are formed on the roots, the seed of subsequent sowing should be inoculated, or soils from established fields in which lucerne is doing well should be strewn over the seed-bed and harrowed in without delay. The nodule bacteria of Melilotiis spp., and. it is believed, that of Burr Clover and Yellow Trefoil, are thought to be symbiotic with lucerne as well. It is probable that the nodule bacteria of some wild, commonly occurring legumes in South Africa may suffice for the lucerne plant. On the other hand, it is doubtful whether failures due to this cause often occur in South Africa. The soil method of inoculation is the most practicable. Artificial cultures, generally speaking, have proved unsatisfactory, Early Treatment. — The young lucerne should not be cut too early unless smothering by weeds is threatened, in which case it should be mowed as low as possible. If it flowers and starts seeding before the winter sets in, it should be mowed, as the young plants must not be allowed to fruit, since this tends to set back the growth. Young lucerne plants should on no account be pastured, and never when the soil is wet. Irrigation. — Irrigate as little as possible before the plants are well established. Depending somewhat on the rainfall, one irrigation, as soon as the crop is taken off, is usually suffi- cient. As soon as the soil permits, after this watering, it should be thoroughly cultivated with heavy cultivators, of which several kinds have been introduced, namely, the Martin Cultivator and Roberts' Lucerne King Cultivator. Disc har- rows are often used where these latter implements are not available. LUCERNE. 147 If the ground is not weedy, a deep and thorough cultiva- tion before growth starts in spring" may be all that is necessary. Lucerne should not be irrigated with water heavily charged with alkali or silt. The latter tends to pack into a hard, impervious crust, very detrimental to the crop. Over-irrigation may easily occur, especially if the subsoil is of an impervious character, and the crop may be killed if submerged for any length of time. Harvesting. — The first cutting of the season is generally the lowest yielding. If the plants are of a retarded and stunted growth, it should be cut, since this often ensures a good second crop. The crop should be mowed when about 10 to 20 per cent, of the plants are in flower. This stage will be found to corre- spond with a slight yellowing of the lower leaves, and the appearance of young shoots at the crown. Mowing should not be delayed until these young shoots are long enough to be cut. As the leaves contain 70 to 80 per cent, of the protein of the whole plant, their preservation is of chief importance. Even with careful management, however, a loss of 10 to 20 per cent, of the leaves will take place. The Kansas Experimental Station cut lucerne in three stages, i.e., when about 10 per cent, in bloom, 50 per cent, in bloom, and in full bloom. That cut when 10 per cent, in bloom was found to be richer in ash, protein, and fat, than that produced by later cuttings, while the crude fibre and the N — free extract increase in per- centage as the plant matures. Harcourt, at the Ontario Agri- cultural College, says : " A much larger amount of digestible matter was obtained by cutting when the plants were about one-third in bloom than by cutting two weeks earlier or two weeks later." Mowing, then, at the time recommended gives the most nutritious and least fibrous hay. After cutting it should be allowed to lie until the leaves wilt, but should then be raked into windrows before they be- come dry and brittle, and later cocked. In hot weather, cutting in the morning should be avoided — it should be cut in the afternoon, raked and cocked the following morning. Be- fore stacking, the hay should be sufficiently dry to prevent over-heating in the stack. It may be taken as fit for stacking if no moisture exudes when a wisp is rolled and twisted sharply into a rope. The hay should be stacked on boards or stones, and if not stacked in barns should be covered with straw to facilitate the shedding of rain. 148 CHAPTER IX If harvested in the right condition and properly cured the hay should have a bright green colour and a pleasant aroma. Yields. — The number of cuttings will vary according to the available moisture, length of growing season, productivity of the soil, and the variety grown. In South Africa, under irri- gation, 4 to 9 cuttings, giving in all 8 to 6 tons of hay per acre, are obtained each season, and without irrigation 2 to 5 cuttings, yielding 1 to 2 tons. The highest yields are obtained g ^ in the third and fourth seasons, but under favourable condi- ^ tions good varieties will continue to yield well up to 8 and 12 f^ "c years. ^^ 5^. Generally speaking, the crop is only ploughed up when, ^ tI o ^ t. •5 s S -2 G- i^'Si w rt => « f <^- s 'Eb 3 H ^ >-c: a< CO c H X — o o S , • — W H 02 III O O 3 H .Si^-^ TJ ^■E^i • 3 > r-i s S ^1 , , "5) cB 5 Pj o jH s s 3 H g g O 1 i ^ u -^ S E-i Ph Tj ■^ 3 w 'o c5 3 OQ 'j • S o S H '5 ^ ^' H ,2 c 6 nl •^ '73 ^ « H E re it is grown as stock feed. The seed is enclosed in chaff after threshing. It is a good yielder. Early and late varieties are found. Emmer has very slender straw and many haulms, and is earlier in maturity than Speltz. The threshed grain contains about 22 per cent. hull. It is very drought-resistant and free from rust. It affords excellent pasture and, in the drier parts of South Africa, may play a more important part in stock-food and for grazing when known. WHEAT. 235 T. spelta (Speltz). — Grains enclosed in glumes, grows better on poor, dry soils than most wheats, except emmer. Ears, long and usually beardless; strong, upright straw, very subject to rust. Much poorer in yield than emmer. Threshed grain contains about 30 per cent. hull. The crushed grain is used as a concentrate in stock-feeding. Distinguishing Characteristics of Emmer and Speltz. — Emmer is always bearded, has short compact heads, consider- ably less hull than Speltz ; the rachis attached to the spikelets is sharp and pointed; and, finally, emmer is much more drought and rust-resistant than speltz. Speltz is nearly always beardless, has long and open heads, the rachis attached to the spikelets is broad and flat, and the plant is very susceptible to rust. These three wheats — Einkorn, Emmer and Speltz — have possibilities from the point of view of the plant-breeder, but commercially they are of little economical importance. T. polonicmn (Polish Wheat). — Heads, very large, eight inches long and one inch thick, chaffy, with outer glumes one inch long, grain translucent, vei'y pointed (resembling rye in shape), and longest of the wheats, sometimes ^ of inch in length. The straw is slender. Ordinarily it is looked upon as a poor yielder. T. compactum (Club Wheat). — Differs from common wheat principally in its short, stiff straw and short but com- pact head. The yields are usually unsatisfactory, and it is very susceptible to rust. There are numerous varieties which are usually classed among the soft wheats. T. turgidum (Poulard, Kivet or Egyptian Wheat). — Is grown mostly in the hot, dry areas bordering the Mediterran- ean ; some of the heads are branched. They are closely related to the durum wheats, some resemble Club Wheat, and others common wheats. They are usually rather tall with broad, often pubescent or glaucous leaA^es. The culmns are thick, stiff and sometimes pithy within. Spikes are long, often squarely-shaped with long awns, which are white, red or bluish-red in colour, and occasionally black. Spikelets arranged very compactly; glumes strongly and sharply keeled. Those resembling the durums do well in South Africa under conditions similar to those where durums do well. Many wheats classed as dm'ums really belong to this group and vice versa. The grain is semi-hard, and Poulard does better in mild humid climates than in arid parts. 236 CHAPTER XIV T. durum (Durum or Macaroni Wheats). — Next to com- mon wheat this is the most important group in South Africa and elsewhere. As a class its varieties are among the most drought and rust-resistant of wheats ; they are tali and erect, with smooth, bright green leaves, and long, narrow, translu- cent grain of exceptional hardness, which is invariably rich in gluten, but poor in starch. The heads are usually heavily bearded, and vary in colour from light yellow to a bluish-black. Under dry-land, arid conditions, they are superior to other strains of wheat. Because of the density and high gluten con- tent of the seed, they are well-suited for the manufacture of macaroni. They are used to a certain extent in blending flour to increase the strength. They give, however, a dark coloured flour and bread, which from the consumer's point of view is objectionable. In the United States of America this is overcome by bleaching with nitrogen peroxide. T. vulgare (Common Wheats). — This is the chief of the bread wheat groups, Poulard and Club wheats being the two other bread wheats. It is the most grown of all and, probably, about 90 per cent, of the world's wheat belongs to this group. The grain is free, ears awned or awnless, stems hollow, grain white or red. As a class they are high yielders and their period of maturity varies considerably, hence winter and spring wheats in nort.hern countries. Drought and rust-resistant qualities vary with the varieties of the group. The types of wheat fall into two natural groups as to attachment of lemma and palet to grain, as follows : — (1) Naked Wheats, in which the grain comes free from the lemma and palet, and the rachis is tenacious, e.g., T. durum, turgidnm , compactum, vulgare and polonicum. (2) Spelt Wheats, in which the grain remains attached to the lemma and palet, and the rachis is fragile, e.g., T. mono- coccum, dicoceum and Spelta. Principal South African Wheats.^ I^ate . . . . . . Black Persian . Medium to late .. Kubanka, Golden Ball. Bon- Durums . . • • -^ taar, and South Africaa Medeah. Early . . . . Blaok Don. WHEAT. ('OMMON WhBATS. 237 Variety. Maturity. Grain. Awns. Remarks. Rieti Very late Dark red, soft Awn- Shatters badly and hard. tipped. rust resistant. Red Egyptian Medium to Red and soft. Short Drought and late. Awns. rust resistant. Spring Early do. Red, serai-hard and hard. do. WitWolKoren .. do. Round, White, Awn- Very susceptible soft. tipped. to rust. American No. 8 . . do. Small, red, soft. Awn- less. Does not shatter easily. Marquis .. do. Dark, red, hard. do. Wit Klein Keren.. Early. SmaU, white half-hard. Awned Excellent yielder on good soil. Susceptible to rust. Federation Medium. Soft, plump, white. Awn- less. Australian Early to Soft, large. Awn- Early Medium. white, tipped. Gluyas Early Eariy. Soft, large, white, plump. Awn- less. Rust-evading. Early and Late Wheats. — From a practical point of view a classification on relative dates of maturity is important, e.g., on irrigated land in the Transvaal the late wheats must be sown during May, while the early wheats should go in later and may be sown up to the end of July. A late wheat sown late will mature early in December, a period when rust is at its worst ; if sown very late the crop will probably be destroyed by rust before maturing. In colder countries these are known as spring and winter wheats. On these, Percival' makes the fol- lowing interesting observations : "At Reading, where the average minimum winter temperature rarely falls below -3° or -4° C, I have always sown all kinds of wheats in autumn and have rarely observed any damage by frost, even among the most delicate kinds. " There is, however, considerable difference among wheats in regard to their resistance to frost, some being ki'led outright by temperatures which others will withstand without, damage. " Many wheats are little injured at -10° to -15° C, but suffer when the temperature falls much below this. " In cold climates the difference are readily determined, and farmers term the sorts which can be sown in autumn 238 CHAPTER XIV * Winter ' wheats ; applying the term ' Spring ' to those which are deUcate and must be sown after the winter has passed. " Varieties of T. dicoccum, T. orientale, T. durum, T. pulonicum, T. turgidum, and T. pTjramidale are usually delicate; on the other hand, T. sphcr/rococcum , T. spelta, and T. monococcuin are hardy races. Some forms of T. com- pactum, and T. vulgar e are also hardy, while others are tender and die out in several continental winters. Of these, the rapid- growing forms with the erect habit and broad leaves are usually delicate, while the slower-growing late-ripening sorts with narrow leaves which lie close to the ground are hardy. " Sinz found that winter wheats, showing great resist- ance to frosts transpire less, have firmer tissues and higher dry-matter content than spring forms. " I have frequently observed that hares and rabbits pick out and eat typical winter wheats before touching the spring forms when both are grown in the same field." He states further, too, " very distinct differences in the habit of growth are visible in autumn and early spring among young wheat plants of different varieties. Two extreme types are readily recognised— namely, (1) the erect type with shoots that spring up almost vertically, and (2) the prostrate type whose leafy shoots, lie on the surface of the soil. In those of erect habit the young shoots form a somewhat compact tuft, and the culms of the mature plant converge at the base to a narrow point just below ground, resembling the ribs of a nearly closed umbrella. They are very liable to lodge and are easily pulled out of the ground. The tendency to grow in this manner is sometimes seen in plants with only two leaf -blades developed, the first blade then making but a nan-ow angle with the second. In plants of the prostrate habit the first loaf-blade becomes hori- zontal soon after the second blade appears. Later, the several shoots of the young plant come away from each other and soon come to lie close to the surface of the soil, the strongly curved parts at this stage being the short leaf sheaths. The extreme forms of this type are sometimes called by farmers creeping wheats. Wheats with this habit do not easily lodge and are so firmly rooted in the ground that they are difficult to pull up." The reason why farmers prefer the late wheats (and late oats which behave in the same way) for grazing is apparent. WHEAT. 23'J Hard and Soft Wheats. — At present the markets in South Africa do not make much distinction between hard and soft wheats, although some millers -object to the former on account of its hardness. Elsewhere this is one of the major distinctions, hard wheats fetching very much higher prices than soft wheats. Generally speaking, the hard wheats are dark in colour, often translucent, while the soft wheats are light and opaque. The soft wheats show a white starchy interior and the hard wheat usually a dark. The durums are always hard, angular, dark and translucent to an extent not met with in the bread wheats. Some of the common wheats, however, have comparatively hard, translucent grains. In composition the soft wheats are much lower in gluten and make what is called a weak flour. In general, this means they do not make a lai^ge porous loaf of bread. For biscuit and pastry manufacture soft wheats are preferred. Hard wheats have more gluten and make a strong flour, which is especially suitable for making light bread. The strength of flour is mostly duo to the quality of the gluten, which not only makes the dough clastic, but enables the bread to absorb more water, and also gives more pounds of bread ; a hundred pounds of good, strong flour will make 120 or more one pound loaves. Structdre and Composition. — In wheat the aluerone layer is only one cell thick, while in barley it is usually three cells in depth. Bran consists of the pericarp, inner integument, nucellus and aluerone layer. In the process of milling these become detached from the endosperm, which forms the flour. Compared with other portions of the grain the embryo is rich in protein, fat and ash constituents, and though it con- tains a considerable amount of sugar, it has but little starch. Nearly one-sixth of the embryo consists of fat and ash and about one-third protein. The endosperm composes on an average about 80 per cent, of the kernel, consisting mainly of starch with about 8 to 10 per cent, of gluten. Quality. — In wheat quality involves a number of factors, and numerous theories, some of a highly controversial nature, have been put forward. Probably on no similar agricultural subject has so much research been directed. Good wheat should, of course, be free from extraneous matter, and should have a low moisture content. 240 CHAPTER XIT Obviously quality signifies suitability for the purpose intended; thus, wheats of low strength are required for pastry- making, while those exhibiting strength to a considerable degree are necessary for the making of light bread. The miller, of course, is chiefly interested in the milling yield, which, in the case of Minnesota wheat, was found to vary in flour production from 60"4 to 7G'l per cent/ " The percentage of flour which can be produced from any sample of wheat depends largely upon the relative plumpness of the kernels, the texture of the kernels, and the percentage of water they contain. If the texture of the kernel is soft, or represents what is termed the ' Yellow Berry ' condition, the percentage of flour will be reduced, since it is mechanically impossible to free the bran from the floury portions so nearly as when the endosperm is hard and vitreous." The baker, on the other hand, is chiefly concerned with three factors : (1) The " strength " of the flour, or its ability to produce a large loaf of uniformly porous texture. ('2) Absorption, or the relative quantity of water which can be added to the flour in making dough. (3) The colour of the flour and of the crumb of bread made therefrom. Although it might be stated that in general the higher the protein content the stronger the wheat, this statement needs to be considerably qualified, as the nature of the proteins found is of vital importance. The most reliable method of determining this is by actual baking tests. Gluten is found in all wheats and its presence in wheat enables the flour from wheat to be made into bread. As it is absent in cereals, like maize, oats and rye, bread cannot be made from these. Gluten contains the proteins, gliadin and glutenin, and it has been propounded, and since discredited, that the ratio of these two proteins to one another may be responsible for the quality of gluten. The accepted position seems to be that the size of the loaf is dependent on the activity of the enzymes found in the wheat, which convert starch into sugar. This sugar, of course, is fermented by the action of the yeast cells; conse- quently, the more active the enzymes found in the wheat, the more sugar provided for the yeast cells, and, therefore, the greater production of gas. " As a nile it is not practicable to get the dough moulded into loaves and put into the oven before it has been fermenting for about 6 to 8 hours. If the flour possesses an active ferment it will still be rapidly forming WHEAT. 241 gas at the end of this time, and the loaves will go into the oven distended with gas under pressure from the elasticity of the gluten which forms the walls of the bubbles. The heat of the oven will cause each gas bubble to expand and a large loaf will be the result. If the ferment (enzyme) of the flour is of low vitality it will not be able to keep the yeast supplied with all the sugar it needs, the volume of gas formed in the latter stages of the fermentation of the dough will be small, and the dough will go into the oven without any pressure of gas inside it, little expansion will take place, as the tempera- ture rises and a small loaf will be produced."^ Wood shows how the activity of the enzymes can be readily determined. After some excellent research work the same writer says : " After making a great number of analyses, it was found that the amount of soluble phosphate in wheat was a very good index of the shape and texture of the loaf it would make. The toughness and elasticity of the gluten, no doubt, depend on the concentration of the soluble phosphate in the wheat grain, the more the soluble phosphate the tougher and more elastic the gluten, and a tough and elastic gluten holds the loaf in shape as it expands in the oven, and prevents the small bubbles of gas running together into large holes and spoiling the texture." He then outlines a simple method by which the amount of soluble phosphate might be satisfactorily indi- cated from the smallest sample. In a recent publication,' Dr. Saunders makes the following interesting statements : " Baking strength is not inherited as a Mendelian unit character ... as a matter of fact, baking strength is extremely complex, varying from season to season, and being sometimes radically transformed by a year's storage of the flour. . . . The highest baking strength was attained when the wheat was stored about three or four years. . . . Bleaching whitens the flour in a manner somewhat similar to natural ageing, but bleaching does not improve the baking qualities of the flour at all, or certainly not to any clearly demonstrable degree. The material improvement of flour by storage continues whether the flour has been bleached or not." Factors Affecting the Chemical and Physical Compo- sition OF Wheat. — The epidermis, epicarp, endocarp, testa, aleurone layer and embryo are the first formed and the endo- sperm last of all. That is, the framework first develops, then the plastids form starch, and at maturity desiccation takes 242 CHAPTER XIV place. Consequently, any factor limiting starch formation naturally increases the percentage of protein found. Imma- ture, and grain shrivelled through disease, e.g., rust, has a higher percentage protein content. Probably the composition varies most with changes in climate. It is a well-known fact that what may be classed as a soft wheat in some parts of the world, when grown under other conditions may be called hard wheat. Some varieties in some localities will present an opaque appearance, in others both opaque and translucent kernels will be found in the same crop, while in another situation the kernels from the same strain may be entirely translucent. PercivaP states : " The white opaque appearance of the endosperm of mealy (soft) grains is due to the presence of minute fissures, which develop between and within the cells during the desiccation which occurs at the time of the ripen- ing of the grain. On examination of carefully-prepared transverse sections from grains, showing different degrees of mealiness, it is seen that interstices have formed along the line of union of adja- cent cells and around the starch grains within the latter, and the contents of some of the cells have shrunk more or less away from the surrounding cell wall ; these changes appear first near the furrow (crease) and spread radially outwards across the endorsperm towards the aleurone layer on the dorsal side, especially in the basal half of the grain near the embryo. Minute in-egular cavities are also seen in the aleurone cells. From investigations on mealy grains of barley, Brown and Escombe concluded that the interstices are vacuous or only partially filled with air. Such minute spaces are absent from flinty, hard, trans- lucent endosperm, in which all the cells of the tissue are completely filled with starch grains imbedded in a protoplasmic matrix, the whole forming a dense coherent mass. The production of flinty or mealy grains is a hereditary character of some particular races and forms of wheat, e.g., the grains of T. dnruni are almost always flinty, while those of T. vulgare are usually very mealy. Wheats grown on heavy soils have a tendency to produce flint grains, while on light soils the texture of the grains is of a more mealy character. Percival also claims that wheats closely spaced have a higher proportion of mealy kernels than WHEAT. 243 those widely spaced; also, that "forms which ordinarily produce mealy grains only do so under conditions which allow of complete development and normal ripening, for the grains of all wheats harvested in an immature state have flinty endosperm." That the protein decreases with the decrease in rainfall is shown in the following table : — ^ District. 1. 2. 3.' 4. 5. 6. 7. 8. 9. Percentage Protein. 12-82 12-37 12-25 11-56 11-16 10-96 10-75 10-63 9-03 Total rainfall (05—09). 45 inches. 60 „ 58 69 73 82 97 103 , 116 Thus, wheats produced in arid regions have a higher per- centage of protein than the same wheats grown in humid parts, and although the composition of wheat varies markedly in the different varieties, as a whole the above statement is also true. Moreover, climate has an infinitely greater influence on composition than difference in soil may have. In America, soil was taken from a humid part, Pullman, to an arid locality, Ritzville, and vice versa, with the result shown below. ^ Original seed grown at Pullman, 1905 ... 9-58% protein. Ritzsville, 1905 12" 57 Percentage protein. Percentage protein, 1907. Pullman seed on Pullman soil at Pullman Pullman seed on Rit/sville soil at Pullman . Ritzsville seed on Pullman soil at Pullman . Ritzsville seed on Ritzsville soil at Pullman . Pullman seed on Pullman soil at Ritzsville . Pullman seed on Ritzsville soil at Ritzsville . Ritzsville seed on Pullman soil at Ritzsville . Ritzsville seed on Ritzsville soil at Ritzsville 15-64 13-47 15-90 13-50 n-e? 13-26 16-10 13.34 17-01 12-64 17-31 12-76 (lost) 12 55 16-6.3 12-60 244 CHAPTER XIV From this it will be seen that the difference in climate was a dominating factor. However, the soil does influence the composition, but in general farm practice to only a comparatively small degree. The protein in wheat may be increased by high nitrogenous manuring. Hall, at Kothamstead, has obtained wheat in this manner so high in gluten that it was almost impossible to obtain the ordinary baked loaf, the dough being loose, unstable and gelatinous. In Ohio a number of experiments was conducted to ascertain the effect of fertilisers on the physical and chemical properties of wheat. ^ The soil on which the experiments were carried out was very unproductive, normally, 50 per cent, of the grain was shrivelled and undeveloped. By increasing the nitrogen content alone of the soil, this condition of the kernels was accentuated. Potash gave a larger percentage of plump kernels, but the composition w^as about the same as that found in the nitrogen plots. Phosphates improved the physical appearance of the grain to the greatest extent. The nitrogen plots gave wheat of a higher protein content because of the shrivelled grain produced, while the grain from the plots manured with phos- phates gave wheat having a higher carbohydrate content, because of the plumper grain produced. When the soil deficiencies are remedied by judicious manuring the most satisfactory kernels are produced. The following correlations have been noted in this respect : — * (1) The average weight of the kernel varies directly with the length of the development period. (2) The percentage nitrogen varies inversely with the length of this period. (3) The length of this period is the chief determining factor in the final composition of the grain. (4) A relatively high rainfall, particularly between flower- ing and ripening, results in the wheat being lower in protein and higher in starch than when the opposite is the case. The following shows he average constituents taken to form an ordinary crop of wheat in Australia : — WHEAT. 245 Plot. Yield . . Dry matter N. P2O5 . . Potash .. Grain. 52-2 bushels. 766 lbs. 141 lbs. 7-83 lbs. 5-22 lbs. Stbaw. 12-96 cwt. 1,222 lbs. 6-2 lbs. 2-4 lbs. 11-92 lbs. Total Peoduobu. 2,364 lbs. 1,988 lbs. 20-30 lbs. 10-23 lbs. 17-14 lbs. Constituents. Percentage. Federation Wheat. Percentage. Federation Flour. Percentage. Federation Bran. Moisture 10-99 10-48 9-47 Fat 2-37 1-58 4-42 Carbohydrates 73-54 78-56 60-72 Fibre 1-87 -30 7-62 Ash 1-34 1-63 4-09 Protein 9-89 8-45 13-68 Mature wheat straw has a lower feeding value than barley or oats, but a little better than rye, as the following table indicates : — Straw. Oats Barley Wheat Eve Nutritive ratio. . 1 :44-6 . 1 :46-2 . 1 :51-7 . 1:57-9 Climate. — The most suitable conditions are those in which a moderately moist and cool growing-season merges gradually into a warm, bright and dry ripening season. These favour free stooling and development, the formation of a hard glutenous kernel and evasion from fungous diseases. These conditions are to be found in many coastal regions, as well a.s in the interior of continents ; while the more humid ripen- ing season which results in a softer, more starchy grain, is just as widely encountered, thus making wheat, unlike maize, adaptable to large areas in various parts of the world. The wheat areas of South Africa are those having a winter rainfall, chiefly the south-west Cape and Namaqualand. In the parts having a summer rainfall wheat must be grown under irrigation, as the winter precipitation is too small for the growth of wheat on dry-lands. In the eastern Free State, 246 CHAPTER XIV where 20 to 25 per cent, of the rainfall occurs during winter, wheat is only fairly successfully grown on dry-lands. How- ever, the area to wheat there is diminishing, summer crops, chiefly maize, ta.king its place. In the south and south-eastern coastal area, where nearlj' 40 per cent, of the rainfall falls in winter, rust is very bad, and the crop is an uncertain one. In fact this area is spoken of as the " Kust Belt." In the Karroo area, where the rainfall is below 15 inches, wheat free from rust and of very good quality is grown under irrigation schemes, i.e., permanent irrigation dams, saaidam irrigation, and torrential flooding. Soils. — Wheat will do better than the other cereals on heavy soils ; however, generally speaking, loams and clay loams are the best. It requires the plant-food of the soil to be more available than do maize or oats. If green manures or barn- yard manures are used they must reach a more thorough state of decomposition to produce a good effect on the wheat crop than in the case of the former two crops. Moreover, since wheat is very sensitive to soil conditions, it requires a more thoroughly pulverised and compact seed-bed than maize, oats or rye. It prefers a neutral soil, being less resistant to alkali than barley, mangels, cotton or sorghums, and does not do so well on acid soils as rye, potatoes, buckwheat, soybeans and cowpeas. Fertilisers. — In most countries nitrogenous fertilisers are the chief fertilisers applied to wheat. In South Africa the application of nitrogenous fertilisers is not so urgently neces- sary. In the south-west Cape area sodium nitrate or guano are used with good results. Elsewhere this can be supplied sufficiently by the use of leguminous green manures. Phosphatic fertilisers are needed on most soils in South Africa, and if judiciously used will give profitable results, especially where the land has received a green manure pre- viously. Present prices are abnormally high and fertilisers should be used with caution. Each of the applications given below will prove highly beneficial to the crop : — 300 lbs. bone meal, plus 100 lbs. of blood meal, if no green-ma.nuring has taken place, or 300 lbs. guano alone, or 200 lbs. superphosphate, or 200 lbs. to 300 lbs. basic slag, according to the acidity of the soil. WHEAT. 247 Phosphatic fertilisers stimulate root-growth, hasten maturity, and, therefore, assist in combating rust, cause the grain to fill out well and, consequently, make for increased production. Potash fertilisers have not proved beneficial, except in small quantities, in the south-west Cape. The fertiliser is generally applied at the time of seeding by means of the combined seed and fertiliser drills, or else by hand. Where wheat is grown under irrigation, the use of well-rotted kraal manure, about four wagon-loads to the acre, often gives excellent results, when used with light dressings of phosphatic fertilisers. Seed. — The following score-card for seed wheat may be employed in judging the merits of samples : — Possible. 1. Germination 20 2. Size and plumpness 20 3. Freedom from foreign seeds, dirt, and broken seed 20 4. Weight per bushel 15 5. Purity of variety 15 6. Hardness of grain 10 100 (1) Gerrnination. — A high percentage of viable seed, having good vitality, is indicated by brightness of the grain and fullness of the embryo. Old seed usually has a dull appearance, and a dark and streaked embryo. Sprouted grain should be looked for and discriminated against. Repeated germination of the same kernel is possible, but the vitality is much impaired. (2) Seed and Plumpness . — Within the variety the seed should be as large and plump as possible ; this ensures a healthy seedling and an uniform stand. A number of experi- ments have been conducted, often poorly from an experimental point of view, but the results point conclusively to the advis- ability of using large plump kernels for planting. Bolley has shown fairly definitely that shrunken kernels are very often diseased, and, moreover, transmit the disease to the next generation. 248 CHAPTER XIV The fact must not be overlooked, however, that the seed of some varieties is not as plump as others, and allowances must be made when judging such varieties. In the durum and Polish wheats the kernels are angular. (3) Freedom from Foreign Seeds, Dirt, and Broken Seeds. — The presence of weed seeds, dirt, and broken seeds naturally detracts from the value of the sample. In the Union the weed seeds most commonly found in wheat are : Dra- bok or Darnel (Lolium temulentum) , Chess or Cheat (Bromus secalinus), Stinkblaar {Datura stramonium and taiula), Wild Oats {Avena Fatua), and Vetches (Vicia spp.). (4) Weight per Bushel. — Good wheat should weigh 60 lbs. Wheat containing a high percentage of moisture gives a low weight per bushel, and is undesirable. (5) Purity of Variety. — Seeds of other varieties are indi- cated by differences in colour, sometimes by translucency and, of course, by size and shape. (6) Hardness of Grain. — As a class the hard wheats com- mand higher prices than the soft wheats, and moreover the quality of bread made from the former is considered more desirable. Hardness seems to be directly correlated with gluten content, as will be seen from the following results obtained at the Ontario Agricultural College : — Pei'centage Weight per Variety. Crimean Red Banatha Buda Pesth Genesee Eeliable ... Dawson's G. Chaff . Prosperity Abundance The hardness was obtained by finding the breaking-point of kernels in a specially-contrived apparatus. It can be rela- tively ascertained, after a little experience, with a fair degree of accuracy, simply by chewing a few grains. The more trans- lucent the kernels, moreover, the harder the grains. Seed Treatment. — Seed should always be treated for the prevention of " Stinking Smut." A formalin mixture, one pint to 40 gallons is usually employed. The grain should be placed in a heap on a canvas or the floor, sprinkled with the solution then shovelled until thoroughlv wet. It should then Hardness. gluten. bushel 18-2 31-4 62-8 17-4 31-5 630 17-5 32-5 62-6 15-8 29-6 63-0 15-3 26-3 61-1 141 27-0 61-4 14-8 26-5 61-4 WHEAT. 249 be covered over with sacks or a tarpaulin for three to four hours, after which it should be spread out to dry. If forma- lin is unobtainable copper sulphate (blue vitriol) may be dR«;d at the rate of one pound to ten gallons of water. The seeds should be sprinkled until wet, and then dried immediately, not being left in a heap, as in the case of the formalin treat- ment. In both cases about one gallon of the solution is required for each 50 pounds of seed. In practice, " Loose Smut " can be treated only with difficulty by Jensen's hot water treatment. Rate of Seeding. — On dry-lands 30 to 45 lbs., on irri- gated land 60 to 80 lbs. should be sown. Drought is better withstood by thin seeding, because each plant develops a stronger root-system, and the available moisture and plant- food go further than in the case of thick-seeding. The rate of seeding, however, is governed by : — (1) Climate. — The lower the average rainfall of the area the less seed is required. (2) Time of Sowings. — Crops sown early require less seed than the same variety sown late, because wheat sown late does not have the same chance of stooling as that sown early. (3) Character of the Seed-Bed. — To choke weeds, wheat should be sown more thickly on foul land, and on sandy soil less than on good clay loams. (4) Character of the Variety. — Some varieties stool more than others ; while some varieties are much earlier than others. (5) Methods of Sowing. — Whether drilled or broadcasted, 25 per cent, more is required when broadcasting than when drilling. Where possible wheat should be put in a seed-drill. The advantages of drilling over broadcasting are briefly as follows : (a) Economy of seed — which is no mean consideration over large acreages. (b) Uniform planting and covering of seed. (c) Better stand, and more even ripening of crop. (d) Even and easy distribution of fertilisers, when fertili- ser-attachment is used. (e) Increased yield, as shown repeatedly by experiments. The seeding takes place from April to the end of July. The bulk of the crop under irrigation is sown during May and June. On the Highveld wheat is sometimes put in as a spring crop during the months of August and September. 250 CHAPTER XIV In the Western Province of the Cape, the crop is sown from April to May, while in the Eastern Free State it is put in from April to June. Both very early and very late plantings are not recom- mended. The former runs the risk of the plants being killed by frost when in the flowering stage, and in the latter the plants often succumb to rust. Cultivation Before and After Seeding. — The pre- paration of the soil on irrigated lands need not be as thorough as that on dry-lands. On the latter the ground should be ploughed early, about January, and left rough so as to ensure maximum penetration of rain. If weedy, cultivation will be necessary. When ploughed very early a shallow-ploughing shortly before planting will be advisable. If the ground is very loose or cloddy a roller might be used to compact the soil and to reduce the clods. If this is not available, a weighted disc- harrow will do good work. The reasons for a compact seed- bed are : — (1) A loose soil will not allow proper root development if air spaces are too large. (2) A loose seed-bed is apt to dry out quickly. (3) If not compacted the undecayed stubble and weeds turned under prevent good contact with the sub-soil and mois- ture does not move about freely. (4) The soil particles come into more intimate touch with the seed and the tender seedling has a better opportunity of developing. It should be harrowed after this and then the seed drilled in. After the wheat has become well rooted, it should be har- rowed with a light harrow, this can be done once or twuce until the wheat is about 6 inches high, or until the crop starts piping. The object is to break any shower crusts, which are liable to form on certain soils and to aerate the soil. If broad- casted the seed will have to be disced in, or covered by harrowing. Irrigation. — The ground should be moist enough at the time of planting to ensure good germination and a fair growth before the first irrigation is necessary. The number of water- ings will depend largely on the character of the soil, the rain- fall during growth, and the variety. It should not be neces- sary to irrigate more than twice before the piping stage. However, from the time of piping until the grain is well-formed the crop is most in need of water and it should WHEAT. 251 then receive liberal irrigation. Irrigation after the grain has been well filled is of no use, as the roots cease functioning about three weeks before the crop is mature. Experimental work in various parts of the world, and observations in South Africa, show the tendency in practice to over-imgate. The necessity for irrigation is shown when the plants present a flaccid and yellowish appearance, the tips of the leaves turn- ing brown. Rotations. — As in most crops in the Union insufficient attention has been paid to this important aspect. As wheat may be classed as a delicate feeding crop, and, therefore, requires readily available plant-food, where practicable, a cul- tivated crop should intervene between a green-manuring crop and the planting of wheat. The effect of previous crops on wheat is well shown in the following result obtained from experiments conducted at Potchefstroom Experimental Farm — viz. :— 1916. 1917. 1918. Pounds. Pounds. Pounds. Velvet beans cut for fodder, wheat following 1,240 1,080 1,040 Cowpeas cut for fodder, wheat fol- lowing 1,400 1,380 1.240 Maize summer crop, wheat winter Crop 800 520 540 Sunflower summer crop, wheat winter crop 400 600 600 No fertiliser was used in the above experiment. The value of the legume, even when used for fodder, is clearly demonstrated. Whenever possible legumes such as cowpeas should be grown on wheat-lands in preference to such crops as maize, sorghums or sunflower. The following rotations are suggested, but, of course, should be altered to suit the conditions of the locality and the requirements of the individual farmer. (!) 1st Year — Winter crop — wheat. Summer crop — cowpeas ploughed under. 2nd Year — Winter crop — wheat fertihsed with phosphates. Summer cro}) — potatoes or mangels. (2) On the Highveld of the Eastern Transvaal, when suit- able, early varieties are used, the following rotation might be successful : — 252 CHAPTER XIV 1st Year — \A'lieat, fertilised with phosphates. •2nd Year — Wheat. 3rd Year — Cowpeas ploughed under. 4th Y^ear — Potatoes. (3) Eastern Orange Free State : — 1st Year — Summer crop — Sudan grass or teff. Winter crop — wheat fertihsed with phosphates. 2nd Y'ear — Summer crop — cowpeas ploughed under. Winter croj^ — w^heat fertilised with phosphates, or — 1st Year — Wheat fertilised with phosphates. Teff cut for hay. 2nd Y^ear — Cowpeas ploughed under. 3rd Year — Maize, with a light dressing of phosphates. (4) South Western Cape : — 1st Year — July-August. Fallow. Field peas ploughed down end of November, followed by summer cultivation. 2nd Y^ear — Wheat, planted in May, fertilised with com- plete fertiliser. 3rd Year — Oats and vetches for hay, sown together in April and May, with a light dressing of fertiliser. 4th Year — Oats for grain, planted in April and May, with a light dressing of fertiliser ; or — 1st Y^ear — Fallow. 2nd Year— Wheat fertilised 40 lbs. Na NO3 100 lbs. basic slag, and 20 lbs. muriate of potash. 3rd Year — Field peas ploughed under. 4th Y^ear — Oats for grain. 5th Year — Oats for hay or grazing. The poor soils of this area are initially poor, and in many cases by a system of continuous cropping have become very unproductive. The remedy would seem to lie in frequent green-manuring, dairy-farming, where the stable manure would be applied to the fields, and the use of artificial fertilisers. Grazing. — Earlv sown crops which have reached too advanced a stage, and which are likely to be injured by frost at the time of flowering, may be grazed down. Late varieties are often planted early with the intention to supply grazing WHEAT. 253 during the winter months ; the stock is turned out of the field at the end of July and the crop then allowed to mature. Harvesting. — Wheat should be reaped with a self-binder or mower as soon as the kernels have reached the hard dough stage — i.e., when an impression can still be made with the finger nail. Maturity will be completed in the bundles. If allowed to become too mature heavy losses will occur through shattering, particularly with some varieties. It should be stocked in shocks of 10 to 12 bundles and allowed to mature fully and to dry-out in these shocks. It should subsequently be stacked ready for threshing. If stacked too early the grain may be seriously damaged by over-heating. Where a header or stripper is used the crop is harvested when fully mature. Threshing. — In growing wheat for seed the first few- bags run through should be put aside as these are likely to have seeds of other varieties and impurities carried by the thresher from the last farm. If the wheat has a large percentage of impurities or shrunken seeds due to rust, poor soil or drought, it should be winnowed. The tailings can be used as stock and chicken food, etc., but if sold with the good wheat the price will be very much decreased. With the introduction of elevators wheat grades will probably be introduced and quality will receive more marked attention than at present. Uses. — It is chiefly used for bread-making purposes, also in the manufacture of macaroni, vermicelli and breakfast foods such as grape-nuts, puffed-wheat, etc. ; it also finds its use in the distilling of alcoholic drinks such as whiskey. The grain as well as the by-products, bran, pollards, etc., is used as stock food. The straw as previously stated is low in nutri- tive value; but is sometimes used as a roughage, bedding, and for a great number of commercial purposes. The crop is also grown paj^ly for grazing and for hay, the latter particularly in countries like Australia. Wheat Improvement. — Wheat is self-fertilised. Natural hybrids are rarely found; consequently, improved strains are easily kept pure. The popular belief that wheat degenerates, and, therefore, a change of seed is necessary, is unproven. Zavitz has grown the same varieties for nearly thirty years, and the present yield is somewhat in advance of the original yields. Montgomery says : " While every grower should always be on the look-out for new or improved varieties, he should, in the main, grow the variety that long experience 254 CHAPTER XIV has shown to be the best for the region, and should try the new varieties only experimentally." The main points to be kept in mind in breeding wheat are : — (1) Drought Resistance. — Some varieties resist drought better than others — e.g., the durums ; while others are drought- evading because of their early maturityr— e.(/., Gluyas Early. (2) Rust Resistance. — Immunity varies with the varieties, some evade rust by early ripening. On the whole, the question of immunity to rust is really little understood. Varieties have been known to be rust-resistant to a marked extent for several years in the Union — e.g., Bob's Rust Proof — Hnd subsequently suddenly to lose w^hat immunity they appear to have had. (3) Strength of Straw. — Varieties vary markedly in this respect, and those having weak straw are apt to be " lodged " or laid badly, the straw lying on the ground or nearly so. When this occurs naturally the crop is very much diminished, through discoloured and sprouted grain ; and , of course , a great deal of ditiiculty is experienced in harvesting lodged wheat. Lodging is best seen after pelting showers or in very windy weather. It may be due to the inherent weakness of the straw of certain strains where the " hypoderm and mechanical tissue round the vascular bundles are reduced and their indi- vidual cells comparatively small and thin-walled. Where the straw is weak, the lower internodes are usually bent or broken when lodged." On the other hand, lodging may be caused by the weakness of the roots or by a root system having a poor anchorage on the soil. " Where the root only is at fault, the plant goes down as a whole, the straw being rigid and stiff. The peculiar arrangement of the root-system and the strength of the individual roots which are hereditary characters of dif- ferent varieties of wheat, have a great influence upon the lodging of the crop. " In short-strained winter wheats of the Square-hoad type the bases of the straws, just above the ground, bend outwards in the form of a cup, and from their low^er nodes arises a spreading system of adventitious roots ; the first inch or two of the roots below the surface is somewhat rigid and thick- ened considerably, and the cell wall of their tissues strongly lignified. By this spreading arrangement of strong roots the plants are firmly anchored to the soil and prevented from being laid except by the severest storms. WHEAT. 255 "In most spring forms, however, the straws grow up from the ground in a crowded, more or less compact, bundle, spreading very little, and the adventitious root-system con- sists of much thinner, less lignified roots closely contracted and descending almost vertically with very little grip on the sur- face soil ; plants with these root characters are very easily bent to the ground as a whole, although the straw may be as strong and rigid as that of the best winter varieties. " Lodging " of this kind, which may even occur among isolated well-grown plants, is due to weak root-hold; the straw being neither bent nor broken."* Other factors also affect lodging. If sown too thickly, insufficient light is accorded the plants and their etiolated condition causes them to lodge badly ; high nitrogenous manuring and over-irrigation also have much the same effect, and certain diseases affecting the lower internodes weaken these to such an extent that lodging of individual straws results. (4) Shattering. — At maturity the grain is shattered out more readily in some varieties than in others. The Kieti variety shatters very badly and for this reason its cultivation has diminished. (5) Stooling. — While not very important, the capacity to stool as well as the manner of stooling varies considerably with the varieties. To quote again from Percival's excellent mono- graph :' " During autumn and spring, however, the primary axis continues to grow very slowly, and, at the same time, in the axils of its leaves buds are formed which expand into short secondary stems; the latter also bear axillary buds, which are capable of developing in a similar fashion into branches of the third order, and so on. Thus, from the primary bud of a single wheat grain, a large number of stems may be produced, which remain very short until April [spring in South Africa] , at which date they usually begin to expand, the strongest of them ultimately growing out into straws, each with its terminal ear. The production of these numerous shoots with unex- panded internodes, which takes place near the surface of the soil, is known as the ' stooling ' or ' tillering ' of the plant ; it is the nominal process of branch-formation in the cereals and grasses generallv." The extent of tillering is governed by the variety — e.g., the late wheats tiller more than the early, but may be modified by environment. Crowded plants tiller 256 CHAPTER XIV less than those widely spaced ; plants on very productive soils stool more than those on poor soils ; a waterlogged condition of the soil inhibits the process, and the date of sowing also affects tillering — e.g., winter wheat sown late does not tiller as much as when sown at the correct date — a strain of wheat which may have only three stems under certain conditions may have under other conditions up to 80 stems. CJiven optimum conditions for nutrition, then the maximum number of stems will be found. It is because of what has been said above that, within limits, widely-differing rates of seeding, except on extreme soil types, on the same soil will give almost identical results as regards yield. (6) Yield. — As in all crops each locality offers conditions more suitable to certain varieties than others. Some strains prove themselves more productive than other strains under widely-differing conditions. (7) Quality of Grain. — This, of course, differs very much with the breeds grown. Some highly-productive strains are of poor quality — e.g.. Federation and Ked Victoria. Methods op Improvement. (1) Mass Selection. — This consists in the continuous selection of a number of the best ears, grains or plants. It is really the elimination of the least suitable for the locality. At the Ontario Agricultural College this method has given the following result — viz. : — 1890-f 1. Oats (average for 8 years) 74 2. Barley ,, ,, 50 3. Potatoes ,, ,, 120 Mass selection is most effective when the individual plant is made the unit of selection, and not the individual ear or grain, because large ears and large grains may be borne on relatively poor plants grown in favourable environment. (2) Individual Selection. — " In this case the selection commences with a number of superior plants of a given variety, and the seed of each plant or ear is separately planted and kept under observation. This enables a strict comparison to be made of the progeny of each selection so that in a few years the best strain in the original selections may be multi- plied for future use.'"^ This is a more tedious, but a more 1894-97. 1898-01. 1901-05. 79 83 100 54 63 63 216 218 249 WHEAT. 257 certain method, of obtaining the desirable biotypes, and is generally confined to experimental stations. However, some valuable varieties have been obtained by farmers selecting out- standing plants. (3) Cross-Breeding or Hybridisation. — Besides the im- portant factor of hybrid vigour, the object is to combine the desirable characteristics of the two or more wheats in the one. The following dominants and recessives have been noted : — DoMiNAKTS. Recessives. Hairy Leaves. Smooth Leaves. Solid stem. Hollow stem. Firm closing of glumes. Loose closing of glumes. Felted glumes. Smooth glumes. Susceptibility to rust. Immunity to rust. Black chaff. White chalf. Fhnty grain. Floury grain. Winter form {late shooting). Spring form (early shooting). Lax ears. Dense ears. Red grain. White grain. Bald J Bearded. Unless reciprocal crosses are wanted, always cross so as to have the mother plant the recessive. Some of the most valuable wheats to-day have been obtained by hybridisation — e.g.. Marquis, Prelude. Federa- tion, the most commonly grown variety in Australia, is a cross between Yandilla King and Purple St»-aw. Whea.t crosses with barley — e.g., Nepaul Barley x Early Lambrigg Wheat gave Bob's Rustproof. Common wheat crosses readily with Emmer, Speltz and Einkorn ; wheat-rye hybrids have also been obtained, and in a few cases these hybrids have been induced to produce seeds; however, on the whole, they are sterile. Diseases and Pests. Rust (Puccina spp.) — The chief menace to wheat-grow- ing in South Africa ; in fact, wheat-growing is really restricted to rust-evading areas — i.e., those areas where the early summer is not hot and moist. Under irrigation, early varieties are fairly safe in the Orange Free State and Trans- vaal, and as a class the durums are very resistant, so is emmer. Occasionally varieties are found more resistant ohaa others; some will remain immune for several seasons, but wij! suddenly become susceptible. No remedy, but resistant 258 CHAPTER XIV varieties, early varieties and early planting, should be resorted to. Smut (Tilletia foetens). — Brand, Burnt or Stinking Smut is of considerable economic importance and can be controlled very easily, as already described. The durums are usually very free from this disease. Loose Smut of Wheat {Ustilago tritici). — No practical remedy. Jensen's hot water treatment, in which wheat is steeped in water at 129° for ten minutes, may be employed where facilities are available. A change of seed is also recom- mended. Take-all, or Vrotpootje (Ophioholus graminis). — This disease has proved serious in the south-west Cape. The best remedial measure is to practise a rotation of crops. There are two aspects of this disease, " Take-all " and " White heads." The condition called " take-all " occurs at an early stage of the growth of the host, causing the latter to become yellow, and often die before a culm is formed. Infection occurs at the base of a plant, wdiich appears black- ened. The condition of " white heads " occurs when the host has attained full growth. The spikes are of normal size, but the grain either remains undeveloped, or is very much shrivelled. The spikes and straw^ appear to be bleached, or prematurely ripened. The entire plant is found to be dry and dead, and for two or three inches at the base of the culm is blackened as if charred. Oats is apparently unaffected by this disease, hence it serves as a good change crop. Wheat Aphis (Toxoptera graminum). — This insect occa- sionally causes a great deal of damage. Pasturing may be of assistance. The spread of this pest is generally controlled by parasites. WHEAT REFERENCES: » " Botany of Crop Plants." — Robbins. ^ Bulletin No. Ill, Pullman Washington. •■' Ohio Bulletin 24,3. ■* Minnesota Bulletin 131. * "The Story of a Loaf of Bread. "—T. B. Wood. " Wheat and Its Cultivation." — Richardson. ' " Nomenclature of Wheat in South Africa." — Union Dept. of Agric. Bulletin No. 1. ' " Breeding of Crop Plants." — Hayes and Garber. » " Wheat, Flour and Bread."— Ottawa Bulletin No. 97. '• " The Wheat Plant."— Percival. CHAPTEE XV. OATS History. — The original wild form of the cultivated oat is not definitely known, although it is believed to have existed in Western Asia and Eastern Europe. Eecords show that the Egyptians, Greeks and Hebrews were not as familiar with oats as they were with barley and wheat. The crop seems to have been first cultivated in Central Europe. The hulless oat is known to have been grown in China 618 to 900 A.D. "It is probable that oats were first used for feeding animals and that their use as human food was confined to times when other grain or food was scarce. Its general use as a fojd for man is evidently of recent origin and is due to the develop- ment of milling machinery. Naturally the people of early times used as a food those grains which could be prepared most easily. For this reason wheat and rye, which thresh clean and contain gluten, were used instead of oats, which usually remain in the hull." Production. Europe North America Asia South America Australasia Africa Average in bushels for 3 years, 1912-U. 2,655,519,000 1,596,864,000 126,361,000 70,767,666 27,285,666 25,398,666 In importance, oats ranks fourth of the world's crops, being exceeded by potatoes, maize and wheat. The world's production in this, as in other crops, shows a gradual but marked increase. 259 260 CHAPTER XV The seven countries leading in oat production are given below : — Yield per acre. Country, Average Yield, 1912-14. 1890-99 1904—13 United States 1,227,021,666 Bushels. 26 1 Bushels. 29-7 Bushels. Russia 959,615,000 Bushels. 17-8 Bushels. 21-6 Bushels. Germany . . 625,406,000 Bushels. 40-0 Bushels. 52-9 Bushels. France 416,604,333 Bushels. 29-8 Bushels. 30-3 Bushels. Canada . . 369,758,666 Bushels. — 34-3 (06—10) Austria-Hungary 249,874,333 Bushels. 25-3 Bushels. 32 0 Bushels. United Kingdom 180,471,000 Bushels. 43-6 Bushels. 43-7 Bushels. The comparatively extensive farming practised in the United States and Eussia accounts for the low acre yield, as opposed to the high yield per acre of Germany and the United Kingdom, where farming of necessity is intensive. African Production. 1911. Bushels. Algeria 11,520,000 Union of South Africa 9,661,000 Tunis 4,650,000 1918. Bushels. 10,790,000 Since fully half the oats grown in South Africa are fed to stock as forage, the total production as grain would be approxi- mately double the amount given above. The order of production by Provinces is the same as in the case of wheat, i.e., Cape Province, Orange Free State, Trans- vaal and Natal, which is to be expected, since the climatic requirements of the two crops are very similar. General Description and Classification.' — The roots are coarser and more numerous, and it is generally accepted that the oat plant is coarser feeding than the wheat plant. The culms are larger and more succulent than those of wheat ; the oat plant, too, is more leafy, and on the average the leaves are wider than wheat leaves, sometimes equalling one and a half inches in width. The inflorescence is a panicle usually 9 to 12 inches in length. Except in the hulless group the kernel is enclosed by the palca and lemma. The kernel proper is usually almost cylin- OATS. 261 drical, very hairy, yellow to brown in colour, with thin and tender bran. Etheridge has classified the principal cultivated oats into eight groups, given in the following outline : — A. Kernel loose within the surrounding hull; lemma and glumes alike in texture — Ave^ia nuda. AA. Kernel firmly clasped by the hull ; lemma and glumes different in texture. B. Upper grains persistent to their rhachillas — Avena sterilis. BB. Upper grains easily separating from their rhachillas C. Lemma extended as teeth or awn points. J). Lemma with four teeth or awn points — Avena ahyssinica. DD. Lemma with two teeth or awn points. E. Lemma elongate, lanceolate, with dis- tinct awn points — Avena strigosa. EE. Lemma short, abrupt, blunt, rather toothed than awn pointed — Avena hrevis. CC. Lemma without teeth or awn points. D. Basilar connections of the grains articulate — Avena fatiia. DD. Basilar connections of the grains solidified. E. Panicles roughly equilateral, spreading Aveyia saliva. EE. Panicles unilateral, appressed — Avena saliva orientaUs. Arena nuda (HuUess Oats) is grown very little in South Africa and elsewhere. The caryopsis is freed in threshing and is usually larger than in common or side oats. The panicle may be of the spreading or mane types. The yields are small and the keeping qualities of the grain are poor. It is grown more as a novelty than as a commercial commodity. Avena sterilis (Red or Algerian Oats). — The upper grains carry with them a part of their rhachillas. The colour of the hull varies from pale red-brown to black, and the caryopsis is more elongated than most of the other cultivated forms. Examples : Algerian Oats, Ruakura, Eed Rust-proof and Burt. 262 CHAPTER XV A vena ahyssuiica (Abyssinian Oats). — The lemma extends into four teeth. Etheridge states that this group is grown chiefly for forage in the desert regions of Abyssinia and Southern Arabia. Avena strigosa (Rough or Sand Oats) and Arena hrevis (Short Oats) are species often occurring wild in Europe, and occasionally found cultivated there. They are of relatively small importance. Aveyia fatua (Wild Oats) is of interest in that it is supposed to be the progenitor of A. sativa and A. saliva orientaUs. The seed is usually brown to black, the base and the rhachilla of which are very hairy, and the lemmas are strongly awned. The awn of the lower grain is very twdsted and right angular. The panicle is very loose and of uneven maturity. The seed when planted has a delayed and uneven germination. It is one of the worst weeds found in winter cereals. Avena sativa (Common or Spreading Oats). — The majority of cultivated varieties belong to this species. The panicle is open and spreading, thus differing from Side Oats, and because the lemma and palea remain attached to the caryopsis after threshing, it can be distinguished from the hulless forms. Examples : Winter Dun, Boer Oats, Potato Oats, etc. Kvenu sativa orientaUs (Side or Mane Oats). — The panicle is compacted and unilateral. The varieties of this species are more restricted to localities and soils than Common Oats, usually coarser strawed, smaller yielders, with a high percen- tage of hull. The panicle is very apt to be broken off by wind. Examples : White Tartarian and Black Tartarian. General. — The colour of the glumes varies — white, black, red, yellow or grey (dun) colours being commonly found. Spring and winter oats are distinguished very sharply from each other in the Northern Hemisphere. Early and late oats are found. Varieties vary in time of maturity from 95 to 150 days, depending to a great extent on the time of sowing. South African Varieties. Winter Dun or English Grey Winter.— A late variety frequently sown for grazing ; if used for this purpose it should be sown in March and not later than April. Tt is very well suited to pasturing and has a spreading panicle and dun- coloured grain. OATS. 263 Algerian. — This variety is grown more than any other variety. It is popular on account of its hardiness, resistance to rust and yielding quahties. Being a robust grower, it grows on soils too poor for Boer Oats. It has a spreading panicle and a yellowish brown grain. Burt and Boer Oats are both early and good forage varie- ties, and may be sown up to the end of July, in which case, of course, they will not stool as much as when sown earlier. Hyjera and Sidonian. — These varieties are identical in the Transvaal, and as they are very rust-resistant, they are often grown as summer crops. They have fair fodder qualities, being tine in straw, but the grain is small and light. This Sidonian appears to be wholly different to the variety grown under that name in the Cape. The grain is white in both cases. O.A.C. 72 is an excellent grain or forage variety of fairly early maturity, and will probably become more popular. It has a spreading panicle, with yellow grain. Texas. — This variety does not grow as tall as Algerian and is slightly later. It has a fine straw and a plump red kernel. Grown extensively in the coastal areas of the South- West Cape. Smyrna. — This is a robust growing variety, with very large grain and very coarse straw. It is about a fortnight earlier than Algerian and does very well under irrigation. Other varieties which have been tried and have given fairly satisfactory results are : Ruakura, Appier, Bancroft and River Plate. In a comparative trial with a number of different varieties at the Elsenburg Experimental Farm, the following results were obtained : — Grain Yield in PouNn.i per Acre. Variety. Average return for 1916 1917 1918 1 1919 four years. Algerian 1,020 1,110 1,030 1,805 1,241 pounds. Sidonian 1 ,060 1,335 1,080 1,375 1,213 pounds. Smyrna 1,120 970 1,098 1,500 1,172 pounds. River Plate . . 95.5 1,025 1,124 1,445 1,137 pounds. Texas 805 1,200 1,014 1 1,525 1,136 pounds. Appier 785 855 900 1 1,655 1,049 pounds. Bancroft 735 885 798 1 1,525 986 pounds. Burt 870 835 1,025 : 990 930 pounds. 264 CHAPTER XV Composition. — The United States Department of Agricul- ture" gives the following analysis of the parts of the oat : — Ash. Protein. Fibre. Carbos. Fat. Oat grain ... 3-3 13-3 lO'T 67-1 5-6 Oat kernal ... 2-2 16-0 VO 131 Tl Oat hull ... 7-2 3-6 32-0 56-1 I'l The hull is seen to be very high in fibre, and the kernel contains a large percentage of fat and protein. The straw of oat hay has a higher feeding value than the straw of any of the cereals. " The proportion of straw to grain, while of course show- ing no constant relation, is comparatively high in oats, gene- rally estimated as two to one, while one and one-half to one in wheat and one to one in maize." — Montgomery. Improvement. — The methods employed are essentially the same as those outlined for wheat. In the Union improvement in oats should be regarded from the following considerations : — (1) The isolation of biotypes having a small percentage of hull. (2) Strength of straw. (3) Disease-resistant strains. (4) Early maturity. (5) High seed-producing strains. (6) Grazing types, i.e., slow, early development, strong root system, and of desirable stooling propensities. (7) Forage types, i.e., fine strawed and leafy. Climate. — Oats are more restricted as regards climatic conditions than wheat, requiring a colder climate with a higher rainfall. Its transpiration ratio is much higher than that of wheat or barley. The following ratios have been obtained : — Oats. Barley. Wheat. Maize. Sorghum. Millet. 614 540 607 368 322 275' The climatic conditions required for oats are very similar to those required for potatoes. Some of the quick maturing varieties, e.g., Boer and Burt, can be used as a catch crop where wheat has been destroyed by Take-all. Soils. The oat crop is a " coarse " feeder as compared with wheat or barley, which may be classed as " delicate " feeders ; consequently it will thrive well on a greater variety of soils than the last-named crops. Extra preparation of land for oats is not so essential as for wheat. Very rich soil, especially Plate XVII A FIELD OF ALGERIAN OATS. LEFT : RVE KERNELS. HIGHT : SOFT WHEAT KEUXELi= LATE XVIII LBA SUGAR-CANE — WINKELSPRUIT EXPERIMENTAL STATION. (COURTESY UNION DEPARTMENT OF Ai JRICULTURE). Plate XIX LEFT : OAT KERNELS SHOWING CREASE AND EMBRYO. RIGHT : CROSS-SECTION OF OAT SEED. SHOWING EMBRYO, ENDOSPERM, ALEURONE LAYER, PALEA AND LEMMA. LEFT : WILD RIGHT : COJIMON OAT.S. Plate XX 1 1 1 ■ ■ ■ 1 1 i'M '''9 H i 1 ^HS.VKH w 1 1 K| iV jr !j J .|h.,„..,.c.^H ■ ■ ■ LEADS OF VARTOUS VARIETIES OF BARLEY. (courtesy MR. J. SELLSCHOP). OATS. 265 in nitrogen, is often not suited to oats, as the crop lodges very readily when the growth is rank. Oats will often do fairly well on badly drained land where other crops fail. It is more alkali or " brak '' resistant than wheat, but like the latter crop and maize, prefers a neutral soil. The field intended for oats should be prepared more or less in a similar way to that described for wheat. If the land has had a summer crop on it, as is often the case, it should be ploughed immediately after the crop has been removed, and if possible worked up into a good tilth before the seeding takes place. Fertilisers. — In older countries fertilisers are usually supplied to some other crop in the rotation rather than to the oat crop. In South Africa phosphates are more often lacking than nitrogen or potash, consequently in the rotation phosphatic fertilisers should be the chief consideration. The application of superphosphate at the rate of 200 pounds, or, Government guano, at the rate of 300 pounds per acre, generally give good results. In the South-West Cape light dressings of nitrate of soda have proved beneficial. Seed.— Oat seed may be judged by the use of the follow- ing score card : — (1) Vitality 20 (2) Size and plumpness 20 (3) Freedom from foreign seed and damaged grain, dirt, etc 20 (4) Thinness of hull 25 (5) Purity of variety 15 Total 100 (1) Vitality. — Seed which will germinate well is of a bright polished appearance. When used for seed, oats must have good vitality, but for feeding purposes too much attention should not be given to this point. Often hulless seeds are found in hulled varieties, and pro- vided the sample is not an old one, it should not be discounted on this account, as these hulless kernels usually escape most easily from thin-hulled varieties. However, hulless oats lose their vitality sooner than do oats enclosed in the palea and lemma. (2) Size and Plumpness. — Within the variety, the larger the seed the better. In all varieties the seed should be plump, 266 CHAPTER XV well filled out ; this indicates a high weight per bushel and satisfactory maturity. For seeding purposes, large, plump seed is very important. At the Ontario Agricultural College the following result was obtained as an average of a seven years' trial : — Large plump seed 62"0 bushels per acre. Mixed sample 54"1 ,, Small seed 46'6 ,, A great many experiments of this nature have been con- ducted at various institutions, and while often faultily planned, the general conclusion to be drawn from them is that the use of large, plump seed for planting is very much the superior. BoUey attributes the governing factor to be one largely of disease, and he is, no doubt, very near the mark. These experiments, too, emphasise the necessity for a greater use of winnowing machines in the Union. (3) Freedo7n from Foreicjn Seed, etc. — Wild oats {Avena fatua) is one of the worst weeds found in the oat crop, and it is almost impossible to separate the seed from that of the ordinary cultivated varieties. The seed of Darnel or Drabok (Loliimi temulentum) is also frequently found in oat seed. (4) Thinness of Hull. —The percentage of hull varies extraordinarily with the varieties, and while, of course, never constant for the same variety, some breeds show an undesirable and consistently high percentage. Since the hull, bran and embryo are formed before the starch is fully developed in the endosperm, naturally anything affecting full development, e.g., unsuitable climatic and soil conditions, disease and insect injury must, of course, affect the percentage of hull. At the Ontario Agricultural College, in apparently well-developed oats this was found to vary from 18*5 to 49'0 per cent, in different varieties. The importance of this point is well shown in the follow- ing figures obtained at the above institution : — Yield. Pounds Pounds Bushel. Percentage per acre. Kernels Kernels Variety. weight. hull. Bushels. per bush. per acre. Joanette . ... 3.3.16 23.8 72.1 25.27 1822 Danbency 35.29 25.1 65.98 26.43 1744 Early Devon . ... 37.67 .34.5 65.18 24.67 1603 Pioneer . ... 32.50 38.0 78.42 20.15 1568 The weight per bushel, while important, is likely to be misleading, e.g., the Early Devon in the above table weighed 37'67 pounds per bushel, but the seed contained 34*5 per cent, hull. The feeding value of the hull is approximately equal to OATS. '267 oat straw, and the real value of the oat from a feeding point of view must be considered from the standpoint of kernels pro- duced per acre. In the preceding table the Joanette variety has a lower yield per acre of seed than Pioneer, yet the former produced 254 pounds of kernels per acre more than the latter. The legal weight per bushel varies in different countries. Thus in the United States 3\i pounds is the accepted standard ; in Canada 34 pounds, and in England 40'2 pounds. At Lulea, in Sv^edcn, in 1904, the average percentage of hull for all varieties was nearly 10 per cent, less than at Svalof , further south.* To ascertain correctly the percentage hull of a sample, 100 pounds of seed should be weighed, the kernels removed and weighed, and from this the percentage of hull is ascertained. By inspection, thick hull is detected by removing the kernel and then feeling the flexibility of the hull between the fingers. It is also indicated when nearly the whole of the palet is enclosed by the lemma, in which case the kernel is nearly always small. If the seed is plump and the palet well shown, the seed is usually proportionately large and the percentage of hull small. The percentage of so-called " double seed " in oats is also of importance in considering this point. A " double seed " consists of the secondary kernel or spikelet enfolded in the lemma of the primary spikelet, the kernel of the latter being undeveloped. Certain varieties give a larger proportion of these double seeds " than others, but rarely above 5 per cent. However, in these the percentage of hull is very high and, moreover, the germination from them is poor. (5) Purity of Variety. — Foreign varieties are detected by colour, length and shape. Seed Treatment. — The seed should be treated with for- malin, the same as for wheat. Time of Seeding. — The time of sowing will vary with the locality, variety, purpose for which intended and w^hether grown under irrigation, drv land or humid conditions. Under irriga- tion the seed should be sown during the months of April and May, so as to provide the crop with a long growing season to stool and reach full development. Early maturing varieties like Boer and Burt may be safely sown as late as July, but the crop is not so productive. For grazing purposes, late varieties, ^.(7., Winter Dun, are best sown on dry lands in February and March, so as to produce a fair growth before the dormant winter period. 268 CHAPTER XV Unless the soil is deep and fertile and has a good water- holding capacity, dry land winter sown oats are not likely to succeed except for grazing purposes. Sometimes on productive soil, with sufficient early spring rains, the crop, after being grazed off in winter, will shoot up again and be ready for har- vesting in November and December. On the highveld of the Transvaal, where rust is not very prevalent, oats are sown on dry lands in August and September with a fair amount of suc- cess. Rate of Seeding. — This is governed by the stooling char- acteristics of the variety, time of the year when sow^n, whether drilled or broadcasted, soil conditions and the purpose for which the crop is grown. For grain production under irrigation, 50 to 70 pounds is sufficient ; without irrigation, 40 to 50 pounds is required. Thicker seeding may be employed on very pro- ductive soils, when sown late, when the crop is to be used for pasturage or for hay, and when broadcasted. The depth of planting and the subsequent treatment of the crop as regards after cultivation and irrigation is identical with that of wheat. Oats and barley are often sown in mixtures in Canada, where the mixed grain harvested is ground and fed to stock. An early variety of oats and a late variety of barley is required in order to get the maturity of the two crops to synchronise. In this way, since the oat has a more extensive and deeper rootinc" system than the barley, a larger total yield is obtained than if the same acreage were divided and sown separately to barley and oats. In the South-West Cape oats, vetches or field peas are often sown together, the vetches, or field peas, being supported by the oats. This is often grazed off or cut for hay, giving a nutritious hay ; moreover, the soil productiveness is not so quickly exhausted as would be the case were the oats sown alone. A few pounds of rape is sometimes sown with the oats. The rape makes very little growth while the oats are growing, but when the oat crop is harvested the rape furnishes a good growth for sheep pasture. Harvesting.— For forage, the crop should be cut when the upper tips of the panicles have turned white and when the plants are changing from a dark green to a yellowish appear- ance. At this, the soft dough stage, the hay is more palatable and most nutritious. A general mistake in the Union is to cut oats for forage purposes when much too mature. OATS. 269 For grain the crop should be harvested when the panicles are quite white and the grain is in the hard dough stage. The crop is usually cut with a self-binder and reaper, or by hand, and the bundles, 10 to 12 in number, are stocked in shocks, where they are allowed to stand until well dried before being stacked. Oat-hay or forage is put on the market in bundles of 5 to 6 pounds, or in bales of 200 to 300 pounds each. The yield of forage is considered good when two to three tons per acre are obtained, and when grown for grain eight to ten bags are procured. These yields are given for irrigable land ; without irrigation — particularly in the South- West Cape — the yields are naturally much smaller. Uses. — In the Union the oat-hay crop is used most exten- sively as a foodstuff for eq nines and as pasturage for sheep. It is also used as human food in the form of oatmeal. The straw, best chaffed, is fed as a roughage to horses, cattle and sheep. The oat grain treated in various ways is used too as a concen- trate for poultry. Diseases. — Smut {Ustilago avence and V . levis). — Loose Smut and Covered Smut are prevalent and often serious. They are readily controlled by the formalin treatment described for wheat. Eust (Puccinia graminis, coronata and ruhigo-vera). — These are very common and destructive. The use of early maturing varieties and early sowing of the less susceptible varieties are the best means of combating these diseases. Spikelet Blight and Blade Bhght are disorders which are sometimes troublesome. The casual organisms have not been identified and no remedy is known. Oats are not supposed to be a host of Opioholus graminis, consequently it should take the place of wheat, or should form a crop in rotations w^here meat is affected with Take-all or Vrotpotje. REFERENCES : " Origin of Cultivated Plants." — De Candolle. " The Small Grains." — Carleton. " Plant Breeding in Scandinavia." — Newman. United States Dept. of Agric., Farmers' Bulletin 420. " Water Requirements of Plants." — United States Dept. of Agric, Bulletin 284. CHAPTER XVI. BARLEY AND RYE History. — Hordeum spontaneum, a wild form, occurs in Asia and is supposed to be the progenitor of our two-rowed forms. A six-rowed wild form is supposed to have existed, since the oldest records of barley describe it as six-rowed. Specimens of grain taken from Egyptian tombs, estimated to be 3,000 years old, are in the British Museum ; representations of barley ears are also found in these tombs. As human food, it was gradually replaced by wheat and rye. Production. The world's continental production for the period 1912-14 is given below : — Europe North America Asia Africa Australia 1912 to 1914. 1,067,210,000 bushels. 250,121,333 ,, 115,816,000 ,, 45,443,666 ,, 4,715,333 ,, The following table gives the leading countries for 1012-14 and their average annual production per acre for the period 1904-1913 :— Average Yield per acre. United States of America Russia Germany Austria-Hungary Japan 198,988,666 Bushels. 471,177,666 Bushels. 162,877,666 Bushels. 152,936,000 Bushels. 98.264,333 Bushels. 25 1 Bushels. 15-3 Bushels. 36-8 Bushels. 25- Bushels. 30- Bushels. 270 BARLEY. 271 South African provincial production according to the 1917-18 agricultural census is : — Total Union Production. Cape Province Transvaal Orange Free State Native Reserves Natal 93,206,000 lbs. 1,876,000 lbs. 1,845,000 lbs. 1,395,000 lbs. 250,000 lbs. 1,790,400 Bushels. 1,790,400 Bushels. (1917—1918) 1,111,700 Bushels. (1911—1912) The average yield is about 18 bushels, of 48 pounds each, per acre. The total production of South Africa is likely to increase considerably, as at present there is a tendency among the farmers in the low veld, e.g., Lydenburg, to go in more for the cultivation of this cereal, which is a more certain crop in those parts than wheat. Uses. — Barley is grown chiefly for malting purposes in South Africa, and the two-rowed barleys, having large plump seed, were considered best for this purpose, until it was dis- covered that good malt can also be produced from Smyrna, a six-rowed type grown extensively in the Western Province of the Cape. To a limited extent barley is also used as a concen- trate in South Africa. It is especially useful in fattening animals. Fairly large acreages are sown for soiling and pas- turing purposes. Prohibition in the United States may of course affect the Union's production adversely. Classification and Description. Genus. Section. Sub-section. Species. Hordeum. vulgar e. Eu. vulgar e. intermedium. vulgare. intermedium. distichon. disticJion. deficiens. Key to cultivated species : — All spikelets fertile (six-rowed barley). Lemmas of all florets awned or hooded — Hordeum vulgare. Lemmas of lateral florets without awns or hoods — H. intermedium . •272 CHAPTER XVI Only the central spikelets fertile (two-rowed barley). Lateral spikelets consisting of outer glumes, lemma » palea, rachilla and usually rudiments of sexual organs. — H. distichon. Lateral spikelets reduced usually to only the outer glumes and rachilla, rarely more than one flowering glume present and never rudiments of sexual organs — H. deficiens. There are thirty-two agricultural varieties and a great many agricultural sub- varieties, the botanical nomenclature becoming somewhat lengthy, e.g., Hordeum dejiciens gymnos- permum typica. HuLLESS Barley. — In these, unlike ordinary barleys, the kernel escapes from the lemma quite freely as in wheat. Varie- ties of these occur in each of the above four species. They are very commonly known as " barley wheat," since the grain re- sembles wheat somewhat. Both the six-rowed and two-rowed barleys may have com- pact (zeocriton) erect (erectum) or nodding (nutans) types of ears. In sample the six-rowed types may be identified by having two-thirds of the grain twisted at the base. Awn Types. —While most cultivated barleys have long, stout awns, there are four types of awns : — 1. Ordinary long, stout awns. 2. Deciduous awns, i.e., drop off as the grains ripen. 3. Awnless or awn-pointed, 4. Hooded or trifurcate types. These various awn types may be found in varictiei^ of all four species. Barley is self-fertilised, and natural hybrids are extremely rare. Colour of Grain. — Ordinary cultivated barleys have a whitish grain, but in some the husk may be black or bluish. In others the grain is either white, green, purple or black. White barleys are prefen-ed commercially, but quality does not seem to be correlated with any particular colour. There are two colouring materials — anthocyanin and a melanin-like compound. These colouring materials may be present in the husks, the aleurone layer or in the endosperm. BARLEY. 273 Winter and Spring Barleys. — Barleys do not stand the same extremes of temperature that wheat or rye do. In mild cUmates, however, winter varieties are grown successfully. In South Africa the practical importance of this is that the late maturing {i.e., winter types) should be sown very much earlier than the early maturing or spring types. Six-rowed. Two-rowed. Varieties Grown in South Africa. Cape six-rowed or Smyrna (awned, white kernels). O.A.C. 21 (awned, bluish kernels). Swedish Gold (white grains, awn semi- deciduous). Six-row Hulless (awnless, huUess, white kernels). Chevalier (awned, white kernels). Invincible (awned, white kernels). Standwell (awned, white kernels). Duckbill (awned, white kernels). The following score-card may be used in judging barley seed, viz. : — 1. Size and uniformity 20 2. Plumpness and texture 15 3. Soundness 10 4. Freedom from foreign matter and seeds ... 15 5. Brightness of colour 15 6. Weight per bushel 15 7. Purity of variety 10 Total 100 (1) Size and Uniformity.— The grain should be as large and uniform as possible. Tw^o-rowed barley is usually plumper, longer and more uniform than six-rowed. (2) Plumpness and Texture.— Good malting barley must be plump, and when cut the surface of the grain should be mealy and snowy white in appearance, and not vitreous. A flinty appearance indicates a high percentage of protein , which is desirable when the grain is used as a concentrate, but is objectionable from the brewer's point of view. The percentage 274 CHAPTER XVI of protein varies somewhat with cUmate and soils, being higher under semi-arid than under humid conditions, and when the nitrogen content of the soil is high. In a good malting barley the protein content should be low and the carbohydrates high. Good samples for this purpose contain 62 to 64 per cent, starch, and protem 9 to 13 per cent. The protein content of barley seed varies from 6^ to 17 per cent. The per cent, hull is usually considered under this point. If the gram is plump the hull is usually thin, particularly when wrinkled across the back, and when two strong veins are absent. For malting, hulled types are preferred to hulless types. (3) Soundness. — There should be no sign of disease, damp- ness or broken kernels. (4) Freedom from Foreign Matter and Seeds. — Dirt and weed seeds must be looked for and the sample discounted accordingly. (5) Brightness of Colour. — A bright appearance is the chief superficial indication of good viability. For brewing purposes at least 99 per cent, of the seeds should be viable, but, more- over, the germination must be even and sufficiently vigorous to show a germination of at least 95 per cent, in 72 hours. If at all weathered or imperfectly matured, the germination will be erratic and the value from a malting standpoint much reduced. (6) Weight per Bushel. — Well matured, plump barley should weigh 48 pounds to the bushel. (7) Purity of Variety. — Seeds of other varieties are indi- cated by difference in colour of the hull and caryopsis, shape and size. For seeding purposes, greater stress must be laid on this point than for malting ; however, a mixture of types is unlikely to be uniform in germination. Malting barley should not be closely threshed, i.e., to give seeds with exposed caryopses. If well threshed a fair number of the grains w^ill be found to have a short portion of the awn adhering. An ideal malting grain of barley is one possessing a relatively short longitudinal and a correspondingly long trans- verse diameter, with both the distal and proximal ends broadly oval. It contains an embryo, with a large scutellum reaching over the edges of the endosperm, and an epithelial layer com- posed of long narrow cells. BARLEY. 275 "An inferior grain of barley is elongated and is pointed at both ends. It contains an embryo with a narrow scutellum and an epithelial layer which is made up of short, broad cells." Composition as Compared with Wheat and Oat Grain. Water. Ash. Crude Protein. Fibre. N-Free Ext. Fat. Nut Rat. Wheat . . 10-2 1-9 12-4 2-2 71-2 21 1: 77 Oats .. 9-2 3-5 12-4 10-9 59-6 4-4 1:6:3 Barley . 9-3 2-7 11-5 4-6 69-8 21 1:7:8 The fibre content is lower, but the nutritive value is less than that of oats. Soil and Climatic Eequirements. — Barley requires a comparatively rich, porous soil, and because of its somewhat weak, shallow root system will often fail on a heavy soil which might yield quite good wheat crops. Unlike rye, it will not grow well on acid soils. It is fairly resistant to alkali, but possesses poorer qualities of withstanding drought than wheat, consequently in the Union it is seldom grown without irriga- tion, excepting in the South- West Cape, where a winter rain- fall obtains. Barley requires a cool growing season, with plenty of sun- shine. Cultural Methods.— These differ very little from those employed for wheat cultivation. Drilling is preferable to broadcasting. The seed should be sown at the rate of 50 to 60 pounds per acre on dry lands, and 60 to 90 pounds on irri- gated land. For grain, early varieties should be sown in April and May, and late varieties from the end of March to the end of April. For soiling, late varieties should be used, and may be planted in February and March so that advantage may be taken of the late summer rains, and, moreover, so that green feeding is provided during the dry winter months. Eotations.— (1) Under Irrigation in Orange Free State and T rails vaal — 1st Year. — Summer crop — Potatoes, fertilised with kraal manure and bonedust. Winter crop — Barley. 276 CHAPTER XVI 2nd Year. — Summer crop — Cowpeas ploughed down. Winter crop — Barley, fertilised with phos- phates. (2) South-West Cape — Ist Year. — Barley (300 pounds guano or 300 pounds bonedust). 2nd Year. — Barley and vetches mixed for hay. 3rd Year. — Wheat, with light dressing of basic slag or bonedust. 4th Year. — Field peas ploughed down and then fallowed. Harvesting. — Barley should be harvested for grain for malting purposes when fully matured, and every precaution should be taken to prevent weathering of the seed, as any dis- colouration markedly decreases the price. For feeding purposes it might be cut earlier in the hard dough stage. At this stage the straw will be more palatable and nutritious. Some of the hooded barleys when grown for seed need careful handling in harvesting, since being very brittle when mature, the ears are apt to break off. These types should not be allowed to become too dry, and should be harvested in the early morning when still fairly damp with dew. When sufficiently dry in the stocks, the crop should be stacked, or in some cases may be threshed without being stacked. The following yields have been obtained in variety trials at Grootfontein Experimental Farm, under irrigation, 1917 : — Cape six-rowed 2,458 lbs. Chevalier 1,386 ,, Beardless Success 1,288 ,, At Elsenburg, 1913, without irrigation : — Duckbill 440 lbs. Grubproof 540 ,, Cape six-rowed 790 ,, Diseases and Pests. — Loose Smut of Barley iUstUago nuda). — This is a parasitic fungus infecting the plant at the time of flowering. The plants grown from seeds matured from infected flowers produce smutted heads ; the following year within a short time after maturity of the spores they are scat- BARLEY. 277 tered by the wind and only the bare stem remains. No practical seed treatment is known, but rotative cropping will keep the disease in check. Covered Smut of Barley (Ustilago hordeii).—The spores mature and are scattered later. They adhere to the grain and can be easily killed by the use of formalin. Immersing the seed for 30 minutes in a solution of one pound of formalin to 40 gallons of water will assist in controlling this disease. Leaf Eust (Puccinia simplex) and Stem Eust (P. graminis hordeii) are both common and can be checked only by growing resistant strains in favourable localities. The rusts of barleys are not, however, such a menace to barley growing as are the wheat rusts to wheat growing. Ergot (Claviceps purpurea) is occasionally found. Care should be taken in feeding affected barley, and it should not be used either for malting or for planting. Yellow Leaf (H elminthosporium grami7ium) is uncommon, and is recognised by a yellowing and splitting of the leaves of young plants. No remedy is known. The Angoumois Moth (Gelechia cerealella) and Weevils (Calandra oryzoi) are often serious storage pests. They can be controlled by fumigation with carbon bisulphide. An Aphis (Toxoptera graminiu7n) may be bad at times and is difficult to control. Grazing down the crop may be of assistance. REFERENCES : » U.S.D. Agric. Bulletin 183. 2 U.S.D. Agric. Bulletin 622.— H. V. Harlan. EYE. Eye is the fifth cereal of importance in the world, maize, wheat, oats and rice being of greater account. It is cultivated in much the same way as wheat and in the Northern Hemi- sphere for very much the same purpose. In South Africa it 278 CHAPTER XVI is grown chiefly for grazing, or as a soiling crop, and occasion- ally, of course, for grain. Production. — Nearly 90 per cent, of the world's crop is produced in Europe, as the following table indicates : — Average for Three Years (191-2-14). Europe 1,751,787,333 bushels. North America Asia South America Australasia 42,259,66(3 33,928,000 1,892,000 174,666 In Europe rye is of about the same importance as is wheat, but in Kussia and Germany more of the former is grown than the latter. Production in the Union is confined chiefly to the Cape Province, where approximately 80 per cent, of the Union's yield is obtained. A fair amount is grown in the eastern dis- tricts of the Orange Free State, but little is cultivated in the Transvaal and Natal. In 1911 the Union produced 675,700 bushels and in 1918 830,700 bushels. However, more rye is grown in South Africa than is indicated by the above figures, since a considerable acreage is not allowed to mature, being pastured and then ploughed down. Origin and Description. — De Condolle states that while rye was known to Pliny, its cultivation when compared with wheat is of comparatively recent times. Eye (Secale cereale) is one of the hardiest and yet one of the least grown of the cereals in the Union. The fact that if closely pastured it may be induced to live over a second winter, shows it to have a tendency towards a perennial form. It is supposed to have originated from Secale montanum anatolicum, a perennial sub-species and native of Western Asia. Unlike wheat, it normally cross-fertilises and all the flowers are fertile. It usually grows much taller than wheat, the stems are thinner, and the first leaf sheath which comes above the ground is of a purplish red colour which distinguishes it from other cereals at this stage. The grain of rye is usually white to grey-greenish in colour, more slender than wheat, not so smooth, with a shallower BYE. 279 crease, sharply pointed towards the embryo end, and charac- teristically blunt at the apex. The percentage of protein is less than found in wheat. It contains gluten, and for that reason can be made into porous bread. The straw is much tougher and more flexible, less palatable and nutritious than that of other cereal straws. It has been crossed with wheat, but only when wheat is employed as the mother plant; the hybrids are usually sterile. Varieties. — Since it is normally cross-fertilised, there are very few varieties. In northern countries winter and spring varieties are grown ; in South Africa these are distinguished as late and early varieties, the former being sown from March until the beginning of May, and the latter as late as the middle of July. Eequirements. — It is best suited to cooler and drier climates than wheat, and will thrive on poorer and more sandy soils than the other winter cereals. The cultural methods are similar to those employed in the cultivation of wheat, but because of its hardiness it will succeed with less favourable soil preparation than the latter crop. It is sown at the rate of 50 to 70 pounds per acre, and must be harvested for grain only when fully ripe. General. — The object in growing rye in the Union is chiefly for grazing and soiling, for which purposes it is admir- ably suited. It will also give fair returns on soils too poor for the profitable cultivation of other cereals. It is surprising that rye is not grown to a greater extent in this country for bread- making, as, in many parts where wheat is at present grown, rye would be undoubtedly more successful than the latter crop. Bread made from rye flour is dark coloured, but very whole- some and palatable. When used for soiling, the crop should be sown at intervals from February to May, and should be cut before the flowers appear, as at later stages the plant becomes too fibrous. Because of its relatively good growth on poor soils, it is often used as a green manure to renovate impoverished soils. The usual prac- tice is to sow early in March, pasture with sheep during winter, and to allow the crop to make a certain amount of growth in spring before it is ploughed under. 280 CHAPTER XVI In America the crop is grown extensively for the straw, which is used for making mats, stuffing horse-collars, and so forth. When grown for this purpose it is cut when the straw is still quite green, made into small bundles and carefully cured. Alcoholic beverages are also manufactured from the grain of this cereal. Eye yields about one to two tons of straw, and under irri- gation 20 to 26'6 bushels of grain (6 to 8 bags) per acre ; without irrigation about half the above is obtained. Diseases. — It is subject to rust, but not to smut, and is usually much more rust-resistant than wheat. It is often badly attacked by ergot, which causes the grains to grow three to five times their normal size, turn black, and be filled with black spores. While of a pharmaceutical value, rye badly infected with this disease, which causes abortion and certain forms of paralysis in live stock, should not be fed. Plate XXI LEFT : KERXEL OF AWNEU, T\VO-R(l\VED BARLEY. RIGHT : KERNELS OF HOODED SIX-ROWED BARLEY. Plate XXII CrOOO POOR. BARLEY KERNELS WITH HULL REJIOVED, LEFT : COOD MALTING BARLEY. SHOWING PRONOUNCED SCUTELLUJI. RIGHT : POOR MALTING BARLEY, OF POOR SHAPE AND SHOWING REDUCED SCUTELLUM. Plate XXIII millets: 1. PEARL JtlLLET (PENNISETUM GLAUCUM) ; 2, 3. 7 AND 8. TYPES OF SETARIA ITALICA ; 5. ECHrNOfHr.OA FRUMENTACEA ; AND 6, PANICUM MILIAf'ErjSr. Plate XXIV TOP KOW : MANdEI.S (A) LONG TYPE. (li) INI ERMEDL\TE, (c) TANKARD. (D) GI.( EOTIO.M ROW : SUGAR BEETS (AFIER PERCJVAL). CHAPTEK XVII. GRASSES AND MILLETS GEASSES. The culture of grasses for animals is mainly an outcome of European civilisation, and then only in regions where Europeans have become estabhshed. In Oriental countries the by-products of crops grown for human beings have been utilised for stock, and only in recent years, and to a limited extent, have grasses been grown for stock. The grasses cultivated for hay, pasture, fodder and soiling play a relatively small part in South African agriculture when compared with that of European, American and even Australian farming. The hay crops of America, composed chiefly of grasses, are valued second only to maize. The reason for this lies, firstly, largely in the fact that, farming in South Africa being still in an extensive phase, stall feeding has not supplemented ranching to the extent it has in many older countries. The chief necessity on the large farms of South Africa is to produce hay and fodder for the winter months, when the natural pasturage does not meet the needs of the stock. As farming becomes more intensive, the cultiva- tion of grasses for pasture, hay, fodder and soiling will doubt- less become more necessary. Secondly, the climate of South Africa is totally unsuited to the growth of many of the grasses cultivated in America, Canada and Europe, e.g., Timothy and Kentucky Blue Grass. Hitherto, experimental work with grasses has rather centred on European and American grasses, and their success on South African farms has been very local and never general. The cultivated grasses in the older countries owe their success to the relatively high rainfall, more evenly distributed than in South Africa, and to the more moderate summer temperatures of those countries. 281 282 CHAPTER XVII The cultivated grasses of agricultural importance in South Africa to-day are all indigenous to Africa, chiefly tropical Africa, and all are exotic to the Union. It would seem, therefore, that new grasses should be sought for, not only in the tropical parts of Africa, but also in tropical parts of other countries. Cultural methods have a tremendously modifying effect upon the environment, and it is possible that certain minor grasses in the grass associations of the Union may be found to be excellent under cultivation, i.e., when not in natural com- petition with the dominant grasses. Most of the commonly occumng grasses of the Union have frequently been tried, and so far none has proved outstanding under culture. CLASSIFCATION ACCORDING TO USE. Hay Grasses. — Hay consists of the entire dried herbage of comparatively fine stemmed grasses or other forage plants. If properly treated, hay is not only grass that is dried, but in which certain fermentative changes have taken place, i.e., curing. Hay grasses are fine stemmed grasses making an erect growth sufficient to enable cutting by mowers, e.g., Teff, Sudan grass, Boer Manna, etc. Fodder Grasses are coarse stemmed grasses cut and dried for stock feed, e.g., Napier grass. Maize, Saccharine Sorghums, etc. Pasture Grasses are grasses grown principally for grazing. These are usually decumbent perennials, having adventitious roots or rhizomes, e.g., Kikuyu grass and Paspalum dilatatum. Grasses are particularly adapted for grazing in that the growing portion is not terminal as in shrubs, but near the base of the grass leaf ; consequently the grass is not injured by having the upper portions of the leaves eaten or cut off. Soiling Grasses are grasses which are cut and fed green to animals off the field on which they have grown, e.g., Phalaris bulbosa and New Zealand tall fescue. Lawn Grasses. — A good lawn grass should propagate by adventitious roots or rhizomes, should be fine and soft in texture, dark green colour, aggressive with vigorous decumbent growth, and perennial, e.g., Bermuda grass and Kikuyu. Soil-Binding Grasses. — These are perennials, more commonly those having adventitious roots or rhizomes, e.g., Beach grass (Ammophila grenaria). GRASSES. 28a Apart from the cereals, the most nnportant cultivated grasses in the Union are : — (1) Teff (Eragrostis ahyssinica) . (•2) Sudan grass {Andropogan sudanense). (3) Kikuyu grass (Pennisetum clandestinum) . (4) Phalaris bulbosa (Toowoomba grass). (5) Napier or Elephant grass iPennisetum purpurcm). (6) The various millets. Essential Factors.— C. V. Piper: " Among the char- acteristics a grass must have to be valuable under cultivation are a satisfactory yielding capacity for the purpose employed, whether pasture, soihng, silage or hay; good feeding quahty, ie., palatable, not too woody, and without any injurious effects; good productive characters, such as abundant easily- gathered seed, or ready multiplication by vegetative methods;, and aggressiveness, or abihty to maintain itself under the condi- tions of culture, and yet not be too troublesome a^s a weed." Under South African conditions, because of our uneven distribution of rainfall, grasses not grown under irrigation must be drought resistant. Cultivated grasses should be high in protein, and low in crude fibre, constituents in which grasses vary very appreciably. TEFF. Teff {Eragrostis ahyssinica). — More extensively grown than any grass in South Africa. At present teff hay is second in importance and in price to lucerne hay. History. — Teff has been grown by the native Abyssinians as a cereal foodstuff probably for centuries. It was introduced into Natal about 30 years ago, and, although favourably reported on, it attracted little attention until again introduced from California by J. Burtt-Davy in 1903. Seed was distri- buted among farmers in the Union in 1904 and subsequent years ; favourable reports were received, and the grass was soon established as one of the Union's important crops. It is supposed to be indigenous to Abyssinia. Description. — It is a summer annual of very rapid growth, as it can be cut for hay six to eight weeks after sowing, and matures seed from eight to twelve weeks. The plant is 284 CHAPTER XVII leafy, with very fine stems, two to four feet in height. If sown and cut early the aftermath will frequently give a very good second cutting. The seed of the variety grown in the Union is very small, dark reddish in colour. Because of its quick growth it is drought evading, but teff cannot be looked upon as a drought-resistant crop. It is essentially a hay crop, to a limited extent a green-manuring crop (the aftermath if not of sufficient grow^th to warrant its being mowed is often ploughed down as green manure), and, being a short-lived and shallow-rooted annual, is not a very suitable grass for pasturage. As a hay crop it is extraordinarily easy to handle and cure. The hay is very palatable and of a very fair nutritive value. It has a protein-content of about 5'5 per cent., being a little higher than that contained in Boer manna, very similar to oat hay, but infeiior to lucerne. The grain contains less protein (8"2 per cent.) than the soft wheats (10 per cent.), but in other constituents it is very similar to wheat grain. The weight of seed is 60 to 72 pounds per bushel. Climate. — Being a summer annual, it is best suited to parts having a summer rainfall. Because of its quick maturity, which enables it to mature often on the soil moisture stored by one or two good soaking rains, it can be grown successfully in comparatively dry regions. In parts having a very heavy rain- fall— 40 to 50 inches — it frequently lodges badly and is some- what difficult to harvest and cure. Its yields are not sufficiently high to warrant its cultivation under ordinary irrigation. It is particularly suited to the Highveld of the Transvaal and Free State, as well as the higher altitudes of Natal, e.g., Mooi River. It is not suited to the Western Province or Namaqualand, but does fairly well in parts of the Eastern Province, Western Transvaal, and in some localities of the Transvaal Bushveld. Soils. — Teff does well on moist soils and, unlike many of the other cultivated grasses, will give good yields on sandy soils. On very rich soils it has a tendency to lodge badly. The seedling is of very delicate growth, and the crust formed by beating rains on some clay soils on drying out often prevents the shoots from reaching the surface. It is a shallow-rooted crop ; consequently, if grown con- tinuously on the same land, it soon exhausts the plant food in the upper surface. For this reason, it has been erroneously described as an exhaustive crop on soils. GRASSES. 285 KoTATiONS. — In rotations it forms an excellent catch crop when the main crop fails. The following five-year rotation is recommended for Highveld farmers : — 1st Year — Maize, and superphosphate. 2nd Year — Maize. 3rd Year— Teff. 4th Year — Cowpeas to be ploughed under. 5th Year — Potatoes, and bone meal. Soil Preparation. — As the seed is extremely small and the seedling of delicate growth, the ground should be in very fine tilth and the seed must be buried only to the slightest degree. After sowing, if the ground is rolled with a Cambridge Poller this will be sufficient. (On moist, heavy soils this instrument cannot be used.) Some of the best stands are obtained by sowing just before rains or by sowing during rains. No further covering of the seed is necessary. Brush dragged lightly over the ground is used by some farmers. Weeders are very useful in this respect, but most harrows cover the seed too deeply. Insufficient moisture for the germination and early growth is one of the chief causes of crop failure. Sowing. — Five to six pounds of seed is used per acre, either broadcasted by hand, with a " fiddle Cahoon Broadcast sower," or a wheelbarrow seeder. To obtain even distribution, the seed should be thoroughly mixed with dry sand or silt — about one to 40. It is often recommended as a smother crop, in which case 8 to 10 lbs. should be sown to the acre. On sandy soils light roUers are employed to compact the seed bed after the seed has been sown. It should be sown from October to the end of January in most parts of the Union, and, if possible, to avoid hay-making in January and February, the wettest season in the Transvaal. Harvesting. — (1) For Hay. — For this purpose it should be mown as soon as the flowers are well out and before the seed has set to any extent. If cut in the afternoon it can be raked the following morning when the dew has disappeared, and cocked in the afternoon. In good weather it can be stacked a day or two after being cocked. For market it should be pressed in bales 16 x 18 x 36 inches. These usually weigh 75 to 100 lbs. Teff yields one to two and a half tons of hay per acre. •286 CHAPTER XVII (2) For Seed. — Teff should be cut as soon as the seed is mature ; if allowed to get over-ripe a good deal of it will be lost through shattering. By sowing early the first crop can be used for hay, and the aftermath for seed. Diseases and Pests. — Striga liitea and a leaf rust, Uromyces tcffi (P. Evans) are found. The latter has not proved serious. Striga lutea can be controlled in some parts by sowing in •October and November, cutting the first crop of hay, which will be before the parasite has seeded, allowing a fair growth of aftermath, and ploughing down the whole. GRASS SORGHUMS (JOHNSON'S, SUDAN AND TUNIS GRASSES). Sudan Grass (Andropogan sudanense). — This is a summer annual hay grass rapidly becoming popular and of increasing importance in South Africa. It was introduced into South Africa in 1914 by the Department of Agriculture (obtained from Khartuuin, Sudan, by the United States of America in 1909). Description. — It is indigenous to Northern Africa, and is believed by Piper to be the wild original form of the cultivated sorghums, since it crosses spontaneously with the cultivated sorghums. It is a tall, leafy grass, reaching a height of six to ten feet, stools very freely, of quick growth, with comparatively fine, erect stems and heavy yielding. It differs from Johnson's grass in that it has no underground stems and is an annual. " The seed of Sudan grass is plumper and larger than that of Johnson grass, and it breaks off from the branch with a small portion of the rachis attached, whereas the seed of the former grass is flatter and breaks off smoothly, with a well- defined scar." Tunis Grass {A. sorghum var. virgatum) has seed with more conspicuous awms, narrower seed, and shatters at maturity while leaves are still green, whereas the seed of Sudan grass is persistent after maturity. The hulls or glumes of Sudan grass are awned (may be broken off in threshing) , and when in flower are often purplish in colour, some fading to a yellow colour when the seed ripens. GRASSES. 287 Up to 200 stems have been counted on one plant, and, as this strong tendency to stool is more apparent after the first cutting, the hay of the aftermath is less coarse than that of the first cutting. Several indigenous grass sorghums {wilde soetriet) are found in the Union. Adaptations. — It is adapted to the same general condi- tions as sorghums, and is one of the most drought-resistant hay crops. Like other sorghums, it will stand semi-dormant during severe dry spells, but renews its growfh vigorously when conditions improve, a distinct advantage over the millets. It will do well on a variety of soils, preferably a rich loam. Soil Treatment. — This should be the same as described for sorghums. Planting. — It can be planted from October to January 31st in most parts of South Africa. November to December, however, are probably the best months. The seed should be buried one to two inches in ordinary soils. For hay, the ordinary drill for small seeds may be used, taking 10 to 15 pounds, or it may be broadcasted at the rate of 15 to 20 pounds per acre. For seed and for hay in the drier parts it is better to plant in 3-feet rows, using 3 to 5 pounds of seed per acre. This allows the crop to adjust itself to the moisture conditions. If planted early, the first crop may be cut for hay, and the aftermath allowed to mature seed. Harvesting.— (1) For Hay.— Little difficulty is experi- enced in drying out or curing. An ordinary mower can be used. In good weather it can be mowed one day, raked the next, cocked the following, and stacked a day or two after the last operation. It should be cut when in full bloom. If the aftermath is to be left to mature seed, the crop for hay should be cut soon after flowering has commenced. Planted at the beginning of November at Potchefstroom, the crop had grown sufficiently to give a heavy yield of hay early in January. If the crop is to be used for hay only, it can be allowed to grow for a considerable time after flowering, as, unlike most grasses, it continues to produce fresh shoots, so that, while some of the stems may become somewhat fibrous, this is counteracted by the addition of the fine young stems. 288 CHAPTER XVII According to the date of planting, two to three cuttings may be obtained, yielding two to five tons of cured hay per acre. Under irrigation in America nine to ten tons are obtained. At Potchefstroom Experimental Station the following yields were obtained :^ " The crop was planted on the 10th November, the flowers appeared on the 12th January, and the crop was cut shortly afterwards, when it was nearly six feet high. The yield w^as '26,200 pounds of green fodder per acre; the second cutting was taken off on the 11th March, when the crop w^as again 8| feet high, and yielded 12,900 pounds of green fodder. The total weight of green fodder from the acre was 39,100 pounds, or approximately 19'2 tons. This yield was obtained under very favourable conditions. Sown for seed purposes on 10th November and harvested on 11th March, it was eight feet high and yielded 900 lbs. of seed, as well as 20,900 pounds of straw per acre." (2) For Seed. — Seed will mature from 75 to 90 days, giving an average yield of 400 to 600 pounds per acre. In Arizona under irrigation Sudan grass yielded 2,250 pounds of seed. The straw from the mature crop is of good feeding value, and is fairly well liked by stock. If well matured and dry, the ordinary wheat thresher will thresh the seed, which weighs from 32 to 44 pounds per bushel, successfully. Composition of Sudan Gbass and othee Havs : (2). Hay Water. Ash. Protein Fibre. N-Free Extract. Fat. Sudan Grass Lucerne . . Millet Tefi 7-20 S-40 7-70 9 02 5-60 7-40 6-20 613 7-94 14-30 7-50 5-50 31-56 25-00 27-70 37 35 45-45 42-70 49-00 40-90 2-25 2-20 210 114 The composition compares favourably with most hay grasses and millets. Sudan grass hay is reported to be more palatable than the millets. Judging from the analyses, it would seem to have a feeding value considerably higher than teff hay. There is very little waste in feeding ; the use of the crop for silage, therefore, does not seem to be warranted, parti- cularly as it is easily made into hay. GRASSES. 289 The analyses given below show the undesirability of allowing the crop to mature fully before being cut for hay. Cut Cut Cut 7th August. 1st 1st Sept. Oct. Before Heads just Beginning Full Before Fully Heading. appearing to bloom. bloom. Heading. Matured. 0/ % % % % % Moisture 6^13 3-54 3-46 3-51 4-82 4-38 Ash 6-61 5-55 5-02 6-64 7-12 5-59 Ether Extract 1-72 1-39 1-23 1-27 1-49 1-48 Protein . . 7-75 6-00 516 4-66 5-63 419 Crude Fibre 30-68 31-94 33-23 35-62 34-30 34-44 Pentosans 21-82 24-01 24-70 24-51 23-38 26-70 Undeter- mined 27-29 27-51 27-20 24-19 23-26 26-70 It is a good crop for soiling, but its use for this purpose is not likely to be extensive, since it is a summer crop. Being a sorghum, it may be dangerous as a pasture crop. As it is high yielding and of very quick growth, it will doubtless play an important part in South African crop rotations. As a catch-crop, where the main summer crop has failed, it is admirably suited. Pests. — It has not been grown for any length of time in South Africa. At present no serious insect pests have been reported, but, since it is sorghum, it is liable to the pests of sorghums — Sorghum Blight {Bacillus sorghi), for instance, has caused considerable damage in some areas of the Union. KIKUYU (Pennisetum clandestinium) . Although Kikuyu under very favourable conditions will occasionally make a sufficiently heavy and upright growth to warrant its being cut for hay, it is essentially a pasture grass. Desceiption. — It is a perennial grass, making its chief growth in summer. The plant is normally decumbent and has numerous thick rhizomes and runners, by means of which it soon establishes itself in the surrounding soil. On rich soil well supplied with moisture an upright growth of 3 to 4 feet w^ill sometimes be made. If required for hay, this should be 290 CHAPTER XVII cut before lodging, which takes place very readily. Although it apparently does not set seed in the Union — the growing season being insufficiently long — it frequently reaches the flowering stage. It is best suited to parts having a warm growing season and a summer rainfall, and has been unfavourably reported on in parts having less than 10 inches of rainfall and in colder parts of high altitude. Nevertheless, it is probably the most drought resistant of the grasses commonly cultivated in South Africa. It remains green until severe frosts occur, and com- mences to grow earlier in the spring than the veld grasses. In the Eastern Province and in Zululand it is said to remain green throughout the year, and in parts of Natal it seems to become naturalised. Soils. — Kikuyu will do well on moist soils. At the Dry- land Station at Pretoria it has given a growth, on a poor sandy soil, of three feet in height. While it gives very good results on a poor sandy soil, and in some parts often having less than 20 inches of rainfalls, the optimum conditions for its growth are found on rich moist soils. On poor soils it responds readily to kraal manure, and doubtless to phosphates where the latter are deficient. Feeding Value and Composition. Moisture. Crude Protein. Carbo3. Fat. Crude Fibre. Ash Kikuyu (Hay).. 8-29 12-36 35 06 1-79 33 08 9-42 Lucerne (Hay).. 8-0 15-5 30-6 2-4 34-8 8-9 Teff(Hay) 8-2 60 43-2 11 34-8 6-7 Boer Manna 71 5 0 42-6 1-5 36-7 6-7 While recent analyses show a variable protein content, in the absence of digestion trials it must be looked upon as very much more nutritious than teff or Boer manna and nearly equal to lucerne. Judging from its chemical analysis, it is outstandingly the most nutritious of grasses grown in South Africa. The experience of farmers who have grown Kikuyu on a large scale bears out this opinion as well. It is apparently very palatable, as it is eagerly eaten by all classes of stock and is pastured in preference to green barley or rye. It is naturally adapted to grazing, as it is not injured by close grazing and stands tramping well. GRASSES. 291 Cultural Methods. — It is propagated vegetatively by planting cuttings of culms or rhizomes, which are character- istic for the long time — from 4 to 6 weeks — during which they remain capable of growing after having been cut or dug up. Good soil preparation is necessary. One of the most successful methods of planting is to throw the cuttings or rhizomes into every third furrow opened by a single-furrow plough, and then cover lightly with the subsequent fun-ow. This should be done during the rainy season. If planted in November or December the ground will often be entirely covered by winter. It is quick-spreading and very aggressive, more so than Quick, when grown in competition with other grasses. It forms a heavy matted growth in a few months. As its growth is very vigorous, it usually becomes " sod- bound " about the fourth year after planting. To remedy this condition it is necessary to plough it over every four years, after which it soon re-establishes itself. No further cultivation is necessary. Because of its heavy growth, it is exhaustive on soils, and where economically possible should be fertilised with phosphates and with available kraal or stable manure. From 10 to 20 bags of cuttings or rhizomes are required to plant an acre. General. — Because of the longevity of the rhizomes or runners when ploughed or dug up, it is likely to prove a troublesome weed, and for that reason should not be planted on land required subsequently for other crops. It is fast becoming the most popular lawn grass in South Africa, because it remains green longer than Germiston or Bermuda grasses and because of the better colour. However, it soon invades flower beds, and should not be used in close proximity to these. In rich soil having plenty of moisture it is valuable as a summer soiling crop. It has proved useful as a soil binder on dam walls, and also on loose sandy soil, and in preventing erosion in dongas. Further, it can be recommended as a grass for planting in poultry runs ; fowls seem very fond of the leaves. Owing to its aggi'essive nature, it can withstand the ravages of the fowls scratching, etc. Dlseases and Pests. — No serious diseases or pests have so far been reported. 292 CHAPTER XVII PHALAKIS BULBOSA (Toowoomba Grass). This is a perennial used chiefly for winter soiling and for hay. It is probably the best winter grass introduced into the Union. P. minor, an annual, is often mistaken for hulbosa. Origin and Description. — This grass is indigenous to the Mediterranean region of North Africa, and has proved useful under Australian conditions. It was imported by Burtt-Davy in 1903, and for a time was incorrectly described as Phalaris commutata. It is a bunch or tussocky grass, having a bluish tinge, and in general appearance somewhat resembles barley. It grows to a height of about three feet. The analysis of Phalaris bulhosa shows a high feeding value, being comparatively rich in protein : — Water. Protein. Fat. Carbos. Fibre. Ash. 21-88 10-06 1-46 34-41 25-98 6-21 This analysis by the Government chemist of N.S. Wales was of grass cut in the flowering stage, and shows a nutrient ratio of 13 : 3-7. It is very palatable. Climate and Soils. — On the Dryland Station plots at Pretoria in 1911 two cuttings and a grazing crop were obtained. It has also given good results in Bechuanaland under condi- tions of very low rainfall. It is fairly hardy against drought and is frost-resistant. Given plenty of moisture and a good soil, it gives a very fair growth during the winter months. It thrives best on rich moist soil, and many failures are due to the grass being sown on unproductive soils. Heavy clay soils should be avoided. Burtt-Davy says : " Where conditions suit it, it gives as heavy a cutting as green barley, and, being perennial, one can keep on cutting month after month without having to resow." Propagation. — The seed costs 3s 6d. to 4s. per pound, and is reported generally to have a low vitaHty. Sow 6 to 8 pounds per acre in autumn. Because of the high cost of seed and poor germination, the seed is usually sown in well-prepared beds, and when the seedlings have made a good growth the crowns are split up and transplanted in rows 2,h x 2^ feet. It is not an aggressive grass, and competes badly with weeds; consequently, the land should be clean before transplanting, and the crop should be cultivated to control weeds. Place in South African Agriculture. — In most parts of the Union it should be planted for soiling and hay on rich soils under moist conditions or under irrigation. Under these circumstances it might take the place of barley to supply green feed in winter. Although an annual barley has a certain advantage in that it requires comparatively little labour in planting. " Its distribution as a farm crop is limited, however, by the fact that it requires rich soil and plenty of water to give thoroughly satisfactory results."" To this must be added the large amount of labour required in establishing the grass. It is sometimes subject to ergot. NAPIER GEASS (Elephant Grass) (Pennisetum purpureum). This is a perennial fodder grass which is teceiving increas- ing interest in the Union and in Australia. It is indigenous to Central Africa and Ehodesia, and was introduced from the latter place in 1912. Description. — In appearance it somewhat resembles a coarse-growing sorghum. It suckers very freely, giving numerous stout stems, which reach a height of 8 to 10 feet in three to four months when once established. North of Nairobi it is said to reach a height of more than 20 feet. It thrives best in a hot chmate on rich soils, but is, nevertheless, fairly drought but not frost resistant. In Australia it has given 25 tons of green fodder after four months' growth. At Hawkes- bery College during the season 1917-18 three cuttings yielded 30 tons, and about 60 tons of fodder were obtained for the whole season. Analysis in Australia gave an albuminoid ratio of 1 : 4 '3.'* Napier's fodder. Green maize fodder. Water 61'81 79-0 Ether Extract 0-29 0'-5 Protein 2-92 1*7 Woody Fibre 14-77 5-6 Carbos 17*29 12-0 Ash 2-92 1-2 While higher than maize fodder in protein, it will be seen that Napier fodder is considerably higher in fibre. Uses. — Its chief value would be in soiling and for silage. It should be cut for silage when the bottom leaves commence to turn brown. Usually two cuttings for this purpose can be 294 CHAPTER XVII obtained in the Transvaal and Orange Free State. As a soiling crop it should be cut earlier than tor silage, probably four to five times during the season. Propagation. — It does not mature seed in the Union, and is therefore propagated by cuttings and rooted slips or roots. Slips should be taken in April. Cuttings should be taken about the same time, and planted so as to leave one joint above ground. Each cutting should have three to five nodes. If the crown is broken up these roots may be planted out. Plants stool abundantly, and should be spaced three feet in the rows and six feet between the rows. Until well established cultiva- tion should be fairly frequent. Cuttings, slips and roots should be planted out in the spring. Previous to this they should be kept in a bed well watered with good drainage. For silage it has a certain advantage over maize in that it is perennial. The silage is probably not as valuable as that of maize, because of the large quantity of fibre content. How- ever, it is readily eaten by stock. CULTIVATED GEASSES OF MINOE IMPOETANCE IN SOUTH AFEICA. A great many gi-asses, exotic and indigenous, have been experimented with in South Africa. Some of these have been cultivated by farmers to a certain extent, but for various reasons have proved themselves poor grasses for our conditions, e.g., Timothy ; some are unpalatable or of low feeding value ; others because of their aggressiveness have become troublesome weeds, e.g., Kweek ; while some have developed ergot very readily, and so have become dangerous to pregnant stock, e.g., Paspalum. Among the most important of what may be called the minor agricultural grasses in South Africa are the following : — (1) Paspalum dilatatum. — This is a native of the tropical States of America, and was introduced from Australia. It is probably one of the best known exotic grasses in the Union, and is sometimes known by the names of Water grass or Breed Zaad Gras. It is a summer-growing perennial, having a strong, deep-rooted system, with numerous leaves near the ground, and relatively leafless stems of a w^eak, spreading character. It is essentially a pasture grass. GRASSES. 295 Adaptations and Characteristics. — It thrives best in wet localities or on low-lying vlei ground. While quickly injured by frost, it is one of the earliest grasses in spring, and at this stage is readily eaten by stock. When allowed to seed it becomes very coarse and unpalatable. In some localities Paspalum dilatatuni has proved to be fairly drought-resistant. Sow 10 lbs. per acre. On account of the following disadvantages, it is becoming less popular every year : — (1) Only at certain times is it really palatable. (2) It is extraordinarily susceptible to ergot. (3) As a weed it is very aggressive. It is distributed and easily propagated by seed, so much so that many farmers who would like to rid their farms of Paspalufn dilatatum have found it has spread so much that its further distribution cannot be checked. This occurs chiefly in parts of the Union where mists are common, e.g., East Griqualand. (4) It is of relatively low feeding value. (2) Paspalum virgatum (Erect Paspalum). — This species is a perennial also in very general cultivation. It is erect growing, reaching a height of five to eight feet in a few months after growth has commenced. While it yields very well, the hay is very coarse, because of the thick fibrous stems. It must be considered a hay grass less objectionable than dilatatum. Provided the rainfall is heavy, it will give a good growth on the poorest soils. Its feeding value is much lower than that of grasses like the Sudan grass. It is similar to dilatatum as regards frost injury and early growth. It is not so aggressive as water grass, and is there- fore not likely to become as bad a weed. While the former is a hay and the latter a grazing grass, a comparison is difficult. On the whole, virgatum is a very much better grass, with decided possibilities as a perennial summer grass for hay purposes. Sow 5 pounds per acre. New Zealand Tall Fescue (Festuca arundinacea) . — This is a perennial grass making a very good winter growth • under moist conditions on good soils. It does not do well on sandy soils. In South Africa Tall fescue (F. elatior), a European grass, has been used instead of Festuca arundinacea. This grass, not being drought or rust-resistant, does not do well, and many failures of the latter are due to sowing seed of F. elatior. 296 CHAPTEB XVII The former grows into tussocks rapidly, is very free from rust, and is not so susceptible to ergot as the paspalums. Young growth is very much liked by stock, but if allowed to grow rank its palatability suffers. It should be sown at the rate of 30 pounds to the acre in February or March, It is a native of the Mediterranean region of Southern Europe, was introduced into South Africa from New Zealand, and has possibilities as a winter pasture grass under iirigation or in moist parts on good soils. Chewing 's Fescue (F. ovina). — This is a fine-leafed pasture grass, best suited to sandy soils in parts of heavy rain- fall, where the climate is not too hot. Sow 15 lbs. per acre. It gives a fair winter growth. Cock's Foot (Dactylis glomerata). — J. Burtt-Davy says : " It is an excellent pasture grass where the conditions favour it, but it is one of the most difficult to establish in South Africa. In a few localities along the Drakensberg, Wakkerstroom, and especially near Kokstad, it appears to do well, but in many localities it seems to die out early and to suffer from drought and rust. Cock's foot is eminently a grass for cool, damp localities." In America it is one of the foremost agriculural grasses. Italian Rye Grass {Loliuvi italicum niultiflorum) is usually a biennial, and has proved fairly successful as a winter grass under irrigation or in the mist belt of the Drakensberg. Seed should be sown at the rate of 30 pounds per acre. It is very frost-resistant and heavy-yielding, but, generally speaking, it is an inferior grass to Phalaris hulhosa. Ehodes Grass {Chloris gayana). — " Is a South x\frican summer perennial grass which is now more extensively grown in America and Australia than in the Union. Ehodes grass develops numerous running stems which root at every joint, and after covering the ground with herbage the shoots assume an upright position, finally attaining a height of 3^- to 4 feet." A very palatable grass, good for pasture or hay. The growing period corresponds with that of Paspalum. Sow 10 lbs. of seed per acre in summer. The seeds require warm, moist weathet for germination. It seeds well, will establish itself if allowed to run to seed, and is fairly drought-resistant. GRASSES. 297 Natal Grass (Pennisetum unisetum) has recently given excellent yields under adverse conditions at the Dryland Station, Pretoria. Star Grass (Cynoden plectostachymum) has been recently tried in the Union, and gives promise of becoming a useful pasture grass. The following grasses have been tried, and only in excep- tional circumstances have any given satisfaction in South xA^frica, viz. : — Rescue Grass {Bromus wildenowii) ; Red Top (Agrostis alba), may do well in marshy ground; Timothy (Phleum pratense) ; Kentucky Blue Grass (Poa pratensis) ; Canadian Blue Grass (Poa compressa) ; Tall Oat Grass (Arrhenatherum elatius) ; Bromus inermis ; Perennial Rye Grass (Lolium perenne) ; Red Fescue (Fcstuca rubra) ; Meadow Foxtail {Alopecurus pratensis) ; Sweet Vernal Grass (Anthoxanthum odoratum) ; Crested Dog's Tail (Cynosurus cristatus), and many others, including most of the more common gi'asses indigenous to the Union. In Rhodesia, Molasses Grass, a perennial, has given excel- lent results as a hay grass. At present little experience has been had of the plant in the Union. REFERENCES: 1 " Teff Grass."— J. Burtt-Davy. * " Agricultural Grasses and Their Culture." — ^Union of South Africa Bulletin No. 5, 1918. * " Sudan Grass as a Forage Crop." — ^U.S.D.A. Bulletin 605. * " Sudan Grass." — Oklahoma Bulletin 103. " " Sudan Grass and Tunis Grass." — J. Burtt-Davy, S.A.S. Farm Series, Bulletin 4. * " Forage Crops and Their Culture." — Piper, pp. 279-284. ' " Sudan Grass."— H. A. Melle, S.A. Agric. Journal, May, 1921. * " Kikuyu Grass."— H. A. Melle, Dept. of Agric. Local Series 45. * " Kikuyu Grass." — " Farmers' Advocate," Jan., 1922. ^^ " Phalaris Bulbosa." — J. Burtt-Davy, "The Sun and Agric. Journal of S.A.," March, 1920. 11 " Agricultural Grasses and Their Culture." — S.A. Dept. of Agric, Bulletin 5, 1918. 1^ N.S. Wales Dept. of Agric, The Farmers* Handbook, pp. 612-614. 1' " Star Grass."— S.A. Agric. Journal. Sept., 1921. 1* Rhodeeian Agric. Journal, Vol. XIII., No. 1. 298 CHAPTER XVII MILLETS (Mannas). In European agriculture these play a different role to that in Asiatic and some African countries. In the latter countries millets have been grown chiefly as cereals, whereas in the former they are cultivated almost entirely as hay crops. It is because of this duality in use that a number of grasses are usually designated " millets," in distinction to the grasses grown tor hav or pasture. The cultivation of millets in South Africa has increased very httle, if at all. They are still grown by the natives for their grain, and as a quick summer catch-crop by a fair number of our farmers. All the millets are rapid-growing summer annuals, usually having an extremely low water requirement, and as such they are admirably suited to " dry-land " agriculture. The following are the principal millets grown in South Africa : — Setaria italica. — These are the Foxtail Millets, and are those most commonly found in the Union. Varieties. — (1) Boer Manna or Common. — This is one of the earhest varieties of this group, and is our most popular variety. It is fine-stemmed, leafy, smaller inflorescence than German, with small yellow seeds in a cylindrical, fairly com- pact head. The variety now called Boer Manna is undoubtedly German Millet. (2) German is usually about three wrecks later than Boer Manna, is much coarser in the leaves and stem, and has a larger, less compact, and distinctly lobed head. The yield is very much higher than Boer Manna, but the quality of hay is not so good. Golden Wonder is a finer strain selected from German. (3) Siberian. — This variety is finer and earlier than Boer Manna, inferior in yielding capacity, and while still grown in South Africa is by no means popular. It is readily distin- guished by its orange-coloured seeds. The ear is smaller and more compact than that of Boer Manna. (4) Hungarian. — This is a fine-strawed variety, with small, compact heads and seeds mixed in colour — yellow, black and purple. It also is grown in various parts of the Union, but is not receiving much attention. History. — Setaria italica is probably a native of Southern Asia, and is of very ancient cultivation, records showing that it was grown in Cliina, 2700 B.C. MILLETS. 299 Millets are erect summer-growing annuals, thriving in parts of high summer temperatures, are quicker maturing than the sorghums, and probably more drought-evading. Generally speaking, they do well in all parts where sorghums are culti- vated. They are extremely sensitive to frost, and for that reason should be sown late. Cultural Methods. — The preparation of the soil need not be so thorough as that required for crops like lucerne or wheat. The ground should be in fine tilth and fairly firm. The Foxtail Millets are usually broadcasted, and can be seeded with a grain drill to advantage. About 15 pounds of seed are required per acre. The seed weighs 50 to 55 pounds per bushel. Sowing should take place from November to January. Hay crops can be cut from 7 to 12 weeks after seeding, accord- ing to the variety and the time of year when sown. On most farms in the Union millets are usually sown after maize planting is completed. Harvesting. — (1) Hay. — When cut for hay the plant should just have flowered. It is cut with the ordinary mower. Millet hay is not of very high quality, and if cut late, when nearly mature, causes disorders in horses — " Millet Fever " — a disease of horses found when millet hay forms the sole diet. If mixed with other food little trouble is experienced. Horses seem to be the only animals affected. Little difficulty is experienced in making hay from this crop. (2) Seed. — The crop is cut with a reaper and binder or by sickle, is allowed to stand in shocks, and then threshed with the ordinary small-grain threshing machine. It is heavy- yielding, 6 to 10 bags being a good yield per acre. Of the remaining millets in common cultivation, Japanese Barnyard {E. jrumentacea) , Pearl Millet (Pennisetum glaucum) and Japanese Broom-Corn Millet (Panicum miliaceum) are the most important in South Africa. Japanese Barnyard. — This is a coarse-growing millet, suited to moist localities, and does well even on very acid soils, e.g., in East Griqualand. It is prolific and gives good growth on very poor soils. It has probably originated from E. crus- galli, a weed very common in America and Canada. It should be sown in November to January at the rate of 25 pounds per acre. Japanese Broom-Corn or Proso. — This is also a native of Asia, and of very ancient civilisation — dating back to the Stone 300 CHAPTEB XVII Age. In South 2\frica it is known as Japanese Broom-Corn or Buff el Gras Millet. The panicles may be loose, contracted at the top and dense. The glumes may be red, black or white ; in South Africa usually the last-named. In Russia and Asia it is invariably grown as a cereal, elsewhere as hay, and often for bird-seed. It is a lower hay-yielder than the Foxtail Millets, and during wet weather is apt to lodge very badly. It is fairly drought-resistant. Pearl Millet, N'Youti or Kaffir Millet. — This is probably indigenous to South Africa, where, as in India, it is cultivated by the natives as a cereal. It is a tall, erect, rapid-gi'owing species, reaching a height of 6 to 10 feet in South Africa and 16 feet on rich soils in Florida. The stems are more slender than those of the saccharine sorghums, the nodes shorter, and the pith dry without sugar content. The head is cylindrical, very dense, 4 to 14 inches long, bearing numerous pearly exposed grains. It takes longer to reach maturity than most grain sorghums, but is more or less adapted to the same conditions as these. The stems are apt to becom.e hard and pithy ; consequently, for hay it should be cut before flowering. Two to three heavy cuttings are obtainable in suitable localities in the Union. It is usually planted in three-feet rows, requiring 3 to 5 pounds of seed per acre ; if broadcasted, about 20 to 30 pounds are required. In South Carolina six cuttings have been obtained in one season, giving an aggregate yield of 47 tons of green matter per acre. At Tweespruit, 1906-7, seed sown on October 5th and harvested February 28th yielded 5^ tons of hay per acre. It is very badly attacked by birds if allowed to go to seed. Large acreages of this millet are grown in the native territories for seed, chiefly for the manufacture of kaffir beer. Diseases and Pests. — Generally speaking, the millets are not subject to serious insect depredations. The Foxtail and Panicum Millets are both attacked by smut, the former by Ustilago crarneri and the latter by Ustilago panici-iniliucei, " both of which infest the individual grains, converting the whole head or panicle into a large black mass, enclosed by bracts in the Foxtail Millets and by a thin, white membrane in the Panicum types." Seed treated with formalin, as recommended for wheat, will control both smuts.. CHAPTEE XVIII ROOT AND ALLIED CROPS These crops are grown for human consumption, some often for the manufacture of sugar, but in the Union princi- pally as a foodstuff for livestock. Their present rdle in South Africa is a small one; nevertheless, in specialised farming, such as dairying and sheep farming, where climatic, soil, and irrigation conditions are suitable, their cultivation is likely to increase. The chief field crops belonging to this group are : — ChenopodiacecB : Beta vulgaris : — (1) Sugar Beets. (2) Leaf-Beets or Chard. (3) Mangel-Wurzels or Mangels or Mangolds. Cruciferce : — (4) Turnip — Brassica rapa. (5) Swede or Rutabaga — Brassica campestris. (6) Eape — Brassica napus. (7) Kale — B. olcracea var. viridis. (8) Kohlrabi — B. oleracea var. caulorapa, Umhelliferce : — (9) Carrot — Daucus carota. Coynpositce — (iO) Jerusalem Artichokes — Heliantlms tuberosum.- A common characteristic of these crops is that during the first season the excessive nutrients not needed for the immediate use of the plants are stored up in the roots, leaves, or thickened stems. They are grown most extensively in European countries and in Canada. In the United States maize silage is mostly used to provide succulent feed during winter, though " roots " are often grown for the special feeding of certain 301 302 CHAPTER XVIII classes of stock, as well as for their tonic value as part of the winter rations. Their chief uses in South Africa are to add succulence to the rations and to supplement grazing during the winter and eariy spring months. 1.— SUGAE BEET. The sugar beet is the principal sugar producing crop of Europe, for which purpose it is extensively grown, particu- larly in Germany. In South Africa, sugar is more profitably produced from sugar cane, and, while having a higher nutritive value than mangels, as a foodstuff for stock, sugar beets are not likely to receive the same attention as mangels, since the latter are heavier yielding and require less labour in harvesting. When grown as a stock-food the cultural methods are identical with those required for mangels. Sugar beets are really strains of mangels which have been specially evolved for their high sugar content, and which, by continued selection, have become fixed types. " They are comparatively small, the best weighing froii^i IJ to 2 J pounds, and of conical or elongated shape. Unlike mangels, the thickened ' roots ' are almost entirely buried in the soil. The roots should not be fanged. In good varieties the skin is white, the flesh firm and white, with a large number of close concentric rings of vascular bundles." x\s the sugar is stored chiefly in the small-celled parenchyma, those having a large number of concentric rings and of a dense consistency are richest in sugar. Beets with upright leaves and long petioles are always less rich in sugar than those with leaves which lie close to the ground and have shorter petioles. Composition. Water-content ... 80 per cent. Cane-sugar ... 15 to 16 per cent, in good varieties. Woody-fibre ... 1"3 per cent. Vilmorin's Improved is one of the best known varieties, and has given good growth under cultivation in South Africa. 2.— LEAF-BEET OK CHAKD. The root is not enlarged. The tender leaves and en- larged petioles are used in the same way as spinach. It is supposed to be the progenitor of the mangel, and was known ROOT AND ALLIED CROPS 303 to the Greeks as a vegetable in 300 B.C. In the Union it must be looked upon as a crop of very minor importance. It is of summer growth, affected by frost, and of poor feeding quality. 3.— MANGEL. The mangel is a biennial of summer growth, grown only for stock-feed. In South Africa, and in most countries, it is the most important of the " root crops." It is a native of the Mediterranean coast and Canary Islands, and has been cultivated in Great Britain for about 200 years. Comparison between the Mangel and Sugar Beet. — " The root of the sugar beet is fairly uniform in shape, being longest near the crown and tapering gradually to a long tap- root, while that of the mangel is of various shapes in the many varieties. The flesh of the sugar beet is white, while that of the mangel is usually reddish or yellow. The skin of the sugar beet is also white ; the mangel may be red, white, golden, purphsh, or even black. The sugar beet grows almost entirely below the surface of the ground, while in many varie- ties of mangel half or more of the root is above the surface, making it much easier to harvest. Well-grown sugar beets weigh from IJ to 2J pounds ; mangels should weigh 4 to 6 pounds. The sugar beet contains about 20 per cent, of solids, of which about four-fifths is sugar ; the mangel contains only about 12 per cent, of solids and not more than 6 per cent, of sugar." In good crops mangels yield from 5 to 8 tons more per acre than sugar beets. Description and Varieties. — Varieties vary principally in colour and shape. According to shape the types are : — (1) Long Type. — These are several times as long as broad, and have proved to be amongst the heaviest yielding and most successful varieties in South Africa. Examples : Mammoth, Long Eed, and Long Yellow. (2) Intermediate. — These are intermediate in shape be- tween the long and globe types. Example : Giant Inter- mediate. (3) Tankard. — Cylindrical and abrupt at both ends. Roots usually small in size. Example : Golden Tankard. (4) Globe. — Globular in shape, usually yellow-fleshed. Examples : Yellow Globe and Orange Globe. 304 CHAPTEB XVin Composition. Golden Tankard Water. ] 86-24 Proteins. Fat. 1-69 -08 Dig. Carbos. 9-83 Fibre. •73 Ash. 1-41 N.E. 1 : 5-9 Yellow Globe 88-19 1-76 -11 7-59 •78 1-57 1 : 4-5 Orange Globe Long Eed . . . 86-91 85-20 2-01 -05 1-54 -04 9-01 11-22 •74 •76 1-28 1-24 1 : 1 : : 4-5 7-3 Giant Half- Sugar White 87-11 1-84 -04 8-60 •85 1-54 1: 4-7 Sugar Beet ... 67-11 2-80 -05 26-95 1-46 1-63 1:9.7 According to feeding experiments conducted in the United States, eight pounds of mangels are equal in feeding value to one pound of maize grain. Calculated on this basis, three times more feeding value is obtained from an acre of roots yielding 20 tons than from one acre of maize yielding 8 bags (26 to 27 bushels). From the above analyses it will be seen that mangels contain a very large proportion of water, and consequently do not contain sufficient nourishment to form the sole ration ; the mangel should therefore be supple- mented with more concentrated foodstuffs, e.g., lucerne hay, maize meal, etc. Its chief value, however, lies in its tonic effect and succulency during periods when feeds of this nature are scarce. It can be fed to all classes of livestock, but as the cost of production of this crop in the Union is rather high, its use as a feed will naturally be restricted to comparatively high-priced stock. Climate and Soils. — Mangels require a warm growing season of about five to six months, and plenty of moisture, for full development. Maximum yields in the Union are obtained under irrigation in somwehat arid areas. After the first two months of growth the plants are fairly drought-resistant. When grown on land not irrigated (drylands), the early growing period must take place after the regular summer rains have commenced. Next to the salt-bushes, mangels are probably the most alkali-resistant of farm crops. They require deep, open, productive, well-drained soils; heavy clays and loose sandy soils should bo avoided. They respond well to manures, particularly nitrogenous manures. ROOT AND ALLIED CROPS 305 The following, taken from Warrington," shows the amounts in pounds per acre of phosphoric acid, nitrogen, and potash, removed by good crops from the soil : — Phosphoric Acid. Nitrogen. Potash. Wheat ... '21-1 48 28-8 Potatoes '21-5 46 76-5 Mangels 52*9 138 300-7 Mangels are looked upon as exhaustive of available plant- food, and that this is correct is to be seen from the above table. They should therefore receive heavy applications of kraal manure, or should follow well-decomposed green manures. On most soils a dressing of 100 to 200 pounds of superphosphate is required. Although the above analysis shows a high potash requirement, and under European conditions the crop responds well to heavy dressings of potassic fertilisers, in the Union 100 to 200 pounds per acre of sulphate of potash is usually all that is necessary. When farmyard manure or green manures are used these must be allowed to become thoroughly decomposed, as the seed-bed should be compact and finely pulverised. Cultural Methods. — A good, fine, mellow seed-bed should be prepared by ploughing, cross-ploughing, and harrow- ing, and, if necessary, rolling to break down clods, to pulverise the soil, and to compact it. Ploughing should be deep and thorough, so as to extend the feeding zone of the roots. Mangels are grown on ridges or on the level. Under irriga- tion the former method is employed, on drylands the latter. On irrigated land the seed is drilled in on top of the ridges, which are generally 80 inches apart. On drylands the width of the rows is usually 36 inches. The seed is put in either by means of a root-crop drill or a single row planter, e.g., Planet Junior, and should not be planted deeper than one inch, except in sandy loams, where the depth may be slightly more. Eidging is necessary for irrigating, and assists in drainage during excessively wet spells. In South Africa, unfortunately, all the seed used at present is imported, and must be tested for vitality before planting, as poor seed is the chief source of failure in this country. Germination tests often show a viability of only 5 to 10 per 306 CHAPTER XVIII cent, of the " clusters." The cotyledons have difficulty in reaching the surface, consequently soils liable to form a crust should be avoided and, if under irrigation, the soil should be kept moist until the seed has germinated. The seed should be soaked and dried sufficiently to allow it to pass through the machine readily, and should be planted only in moist soil. Ten to twelve pounds of seed are required per acre. When the plants are a few inches hig-h they should be thinned out, first by hoe and then by hand pulling, to about 10 to 15 inches in the row. Wider spacing would result in larger roots ; but the feeding quality and quantity per acre is less when too widely planted. For this reason it is preferable to have a larger number of small roots than a smaller number of large roots. When grown without irrigation they should be thinned out to about 15 to 18 inches in the row. Hand thinning is necessary, as the seed cluster contains one to five seeds, and consequently a number of plants may arise from the same cluster. On irrigated land, where the soil moisture can be regu- lated, planting may commence in October, and continued not later than January, but on dry lands it should not start until November, or until the regular rains have commenced. During the early growth, the crop must be hoed by hand two to three times. Narrow tooth cultivators could be used frequently to advantage to control weeds and to break soil crusts. On dry land, before thinning, a weeder may be used. Harvesting. — In America and Europe mangels are pulled by hand, the leaves " topped off," and the roots stored in cellars or pits until fed in the winter. Under the relatively high winter temperatures in South Africa this is impracticable, and the best and most satisfactory method is to leave the roots in situ in the field. The daily requirement is then pulled and carted from the field each day. About 25 tons per acre is considered a good yield. They should be sliced before being fed to stock. If fed heavily when rather immature scouring is often caused. Seed Production. — Seed can be grown readily in the T^'nion by pulling roots at the beginning of June. Only desirable, disease-free roots should be chosen. These are stored in cool, well-ventilated places until October or November. They are then planted three feet by thrp<5 feet in ROOT AND ALLIED CROPS 307 the field, and mature seed about April. Individual plants will yield twelve ounces to one pound of seed. Pests, — Cutworms often destroy young seedlings. The Leaf-Spot Disease, as well as Mangel Kust, often cause a certain amount of damage. 4 & 5.— TUENIPS AND SWEDES. While grown largely in other countries, particularly in Europe, these are cultivated to a small extent in South Africa, and are limited to the mist belt in eastern parts of the Union. In other parts of the country they thrive vcrj'^ indifferently and are often destroyed by plant lice. Plenty of moisture, dull and cool weather, are required for their best growth. They are often pastured in situ by sheep, and are also fed to cattle in the same manner as in the case of mangels. As they taint the flavour of milk they should be fed cautiously to dairy cows. When grown close to towns they are often sold for human consumption. Description. — Swedes (Eutabagas) can be distinguished from turnips by the " neck " found at the top of the root. The flesh is firmer than that of the turnip, and the keeping quality is better. White, but chiefly yellow-coloured flesh is found, the latter being preferred, as the keeping quality is usually superior. The skin may be green, purple or bronze. They are not so easily injured by frosts as turnips, and are one to tiwo months later in maturity. The Farmer's Handbook (N.S.W.) gives the following composition of Swedes : — Water. Ash. Protein. Fibre. Carbos. Fat. 88-6 1-2 1-2 1-3 7-5 •2 Cultural Methods. — They may be planted on ridges or broadcasted. When ridged in rows 2 feet 6 inches apart, two pounds of seed are required per acre ; when broadcasted, about five pounds per acre. The soil preparation is very much the same as that required for mangels. Sandy loams are preferred. The seed sliould not be planted deeper than one inch. If drilled, they should be thinned by hoe, when a few inches high to about 8 inches in the row. Planting takes place from November to early in January. 308 CHArXER XVIII About twelve to fifteen tons per acre is considered a ^'ood yield. If fed to cattle they should be sliced before feediiij;. 6.— RAPE. This is a quick-growing, broad-leafed, succulent, and palatable plant, somewhat resembling young cabbage, two to four feet in height. It makes its best growth in the cooler months of the year. Rape is grown for soiling and for tem- porary pasture for cattle, pigs, and particularly sheep. It is very frost-resistant, and does best under cool con- ditions on rich, moist, loamy soils. It responds w^ell to applica- tions of barnyard manure. The soil should be prepared in January, and the seed drilled or broadcasted in February and March. It can then be grazed off or soiled during May and June. In the Western Province it is often sown in May or June, and then affords a succulent feed in the dry summer months. If drilled in rows three feet apart, two pounds of seed are required per acre ; if broadcasted, five pounds. Dwarf Essex is the best variety grown in the Union. In the United States, rape is often planted between the rows of maize at the time of the last cultivation. The whole crop is later grazed off by pigs, sheep or cattle. Experiments at the Potchefstroom Experimental Farm indicated that soiling was the most economical method of feeding rape to pigs. The advantage to the soil, however, when pastured, should also be considered. Care must be exercised when grazed by sheep or cattle, as bloating is common. Hungry and thirsty animals should not be put into the fields; the de'w should be off, and animals should gradually have their stay in the field lengthened. Twenty minutes twice a day at the commencement, until, after a fortnight, they might be allowed in permanently. 7.— KALE. This crop resembles rape, and is distinguished from it by having entirely smooth leaves, while those of rape are slightly hairy. Chou Moellier and Thousand Headed Kale are strains of kale. ROOT AND ALLIED CROPS 309 The soil and climatic requirements, cultural treatment, and U8es of this crop, are identical with those of rape. 8.— KOHL EABI. " The stem is short, much thickened, fleshy, and stands out of the ground. The fleshy part comes from the stem above the cotyledons, hence is not root. The swelling begins at the ground line; there is formed a large spherical body, upon which are very prominent broad leaf scars — white and purple ' balls ' are formed."^ It is a crop grown under the same climatic and soil con- ditions as rape, and is utilised in the same way; when soiled, the " ball " should be sliced. The composition is similar to that of mangels, but the yield is very much less. If stored, the leaves should be re- moved first. 9.— CAEKOT. Sometimes grown as a field crop for horses. Must be grown under irrigation in the Union. It requires a deep, somewhat sandy, and productive soil. Usually drilled in rows 2 feet 6 inches apart ; three to six pounds of seed are required per acre; planted in March and April. 10.— JERUSALEM ARTICHOKE. This is a native of North America. It is a tall, robust growing plant, reaching a height of six to twelve feet, and in appearance resembles the smaller varieties of sunflower. It produces a large cluster of rhizomes or tubers of special value to pigs, but often used for culinary purposes. The tubers may be red, white, or yellow. It makes its growth in summer. It is a persistent crop w^hen once established and, if grown in suitable soil, is difficult to eradicate ; it is wise, therefore, to set aside a field for artichokes permanently. Enough tubers, as a rule, are left in the ground each year to continue the crop. Waste places or fields difficult for ordinary cultivation may be profitably utilised by growing artichokes. (The Globe Artichoke, Cynara scnlymus, is very different in appearance, but also belongs to the GompositcB. The thick receptacle, together with the fleshy bases of the scales of the involucre, is used as a vegetable. Its use as a stock food in the Karroo is advocated by some.) 310 CHAPTER XVIII Climate and Soils. — The plant is extremely hardy, will withstand moderately adverse conditions of soil, moisture, and frost, and will thrive on most soils. However, good potato soils are best. Loose alluvial soils, containing an abundance of organic matter, well-drained, are among the most produc- tive for this crop. Cultural Methods. — The tubers, planted in September and October, should be dropped in furrows, three feet apart, with a spacing of two feet apart in the row. They are then covered about four inches in depth by turning a furrow-slice over them. About 400 to 500 pounds are required per acre. It responds well to kraal manure. The crop should be har- rowed lightly just after the appearance of the plants above ground, and, if necessary, cultivated. It matures in five months, and is ready for harvesting as soon as the plants have flowered and turned yellow. Artichokes do not keep well in storage, and should therefore be left in the ground and lifted as required. In feeding to pigs, it is best to turn the animals into the crop to root out the tubers. The expense of lifting and cart- ing the crop is obviated, and exercise for the animals is afforded. If the crop is to be continued, the pigs must be taken out before all the tubers have been unearthed. The ground should then be ploughed and harrowed to keep down weeds. Composition.^ Water. Ash. Protein. Carlios. Fat. N.R. Artichoke ... 79-5 1-0 2-5 16-7 0-2 1 : 7 Potato .. 78-9 ro •21 17-9 0-1 1: 8-6 The artichoke has a fairly high nutritive ratio as com- pared with the potato, and is one of the cheapest and healthiest feeds for all classes of livestock, providing succu- lent feed during late winter and early spring. InuUn takes the place of starch in artichokes. In France, the tubers are distilled for alcohol. EEFERENCES: Science Bulletin No. 6, Union Dept. of Agriculture. " Warrington's Chemistry of the Farm." — Dr. Juritz. " Botany of Crop Plants." — Bobbins. " Farmers' Handbook," New South Wales. CHAPTER XIX. FLAX, BUCKWHEAT, SUNFLOWERS AND PUMPKINS FLAX {Linum usitaiissimum) . History. — De Candolle says L. angustlfolium, usually a perennial species, was the first cultivated. It was eventually supplanted by the annual L. usitatissimutn , which has been cultivated in Mesopotamia, Assyria and Egypt for 4,000 to 5,000 years. This region he thinks was its original habitat. Some of the bandages on the mummies in the British Museum are of linen. Description. — The crop is grown for the two products, fibre and linseed, and because the best fibre is not produced by the heaviest seeding plants two distinct types have evolved. The fibre type is small-seeded, uniformly straight, has a com- paritively unbranched stem 2 feet to 3 feet 6 inches, and a small raceme at the top, which eventually bears capsules having five compartments, containing ten shiny, flat, dark brown seeds. The linseed type is shorter, 1 foot 6 inches to 2 feet, more branched, has larger and heavier seeds, with numerous capsules. By close planting the tendency to branching is in- hibited, and plants can thus be produced resembling the fibre type. The common varieties have blue or white flowers ; red- flowered varieties are occasionally found. The fibres, which constitute from 20 to 27 per cent, of the stem, occur in small bundles between the cambium and cortex. Each cell is about one inch in length, and the fibre filament one foot to three feet in length. 311 312 CHAPTER XIX Peodcction. — Most of the flax grown for fibre is grown in Russia, Austria-Hungary, Belgium, Ireland, and other European countries, Russia's share being nearly four-fifths of the world's fibre output. 1914 Linseed Crop. Argentine 39,171,000 bushels British India 15,440,000 United States 13,749,000 In South Africa production is limited entirely to linseed, and as yet no census returns are available, the present output being relatively small. As stable feeding, dairying, etc., become more common, the grow^th of the crop, for linseed is likely to become more important. Uses. — The fibre is used in cloth for wearing apparel (linen), for matting, " crash " and towelling, w^hile the un- retted flax is employed in the manufacture of binding twine. The linseed is very rich both in protein and oil. Oil- cake, a by-product rich in protein, is left after the oil has been extracted. It is a valuable concentrate for stock feed- ing. The oil is very valuable, being used for varnishes in the manufacture of linoleum, in patent leather, and medi- cinally. The straw has little or no feeding value, and at times is dangerous on account of the nature of the fibre, and the prussic acid sometimes found in the growing plant. Composition. Flaxseed and Linseed Cake compared with Wheat ( Montgomery) . Linseed Wheat Flaxseed. Cake. Grain. PercBDtage. Percentage. Percentag Water 91 101 10- 5 Ash 4-3 5-8 1-8 Protein 22-6 332 11-9 Crude Fibre ... 71 9-5 1-8 Nitrogen F. Extract . 23-2 38-4 71-9 Fat (Oil) 33-7 3-0 21 Climate. — Generally speaking, our climatic conditions are not suited for the production of good fibre, because of our uncertain rainfall. Changing conditions of moisture affect the uniformity of length, fineness, and spinning quality of the FLAX 313 fibre. For fibre, a moist atmosphere with frequent showers and a moderately low, uniform temperature, gives the best quality. In favoured South African localities it may be grown successfully for fibre. However, the excessive amount of care and labour required will probably preclude its growth for fibre in the Union. The requirements for seed production are not nearly so exacting, and although the water requirement of the crop is high, it has been grown in various parts of the Union with good results. Soil Kequirements for Fibre. — Uniformity in length, strength, and thickness of fibre is readily affected by a lack of uniformity in the soil. The soil in individual fields should be as uniform as possible. Uniformity in soil for the produc- tion of linseed, however, is not so important. It is a very shallow rooted crop, and if grown on land continuously ex- hausts the upper layer of soil very rapidly. Because of this it is popularly supposed to be an exhaustive crop. Kotative cropping is essential particularly if Flax Wilt {Fusarium lini Bolley) appears as the spores remain viable in the soil for about eight years. Heavy nitrogenous manures must be avoided as well as newly applied barnyard manure, parti- cularly if the crop is to be grown for fibre. The former causes lodging, and the latter uneven growth. In general, soils suit- able for the cereals are suitable for the linseed crop ; the fibre crop, however, must not be grown on calcareous soils, heavy clays, or peaty soils too rich in humus. Rotation. — It competes very badly with weeds; conse- quently it follows cleaning crops best, and is often sown on virgin land. It requires a very firm seed-bed, which is one reason why the crop should not follow a green-manuring crop. Further, as its feeding area is limited, the plant-food should be readily available. Soil Preparation and Planting. — The land should be as clean as possible, and ploughing should be done some time before planting. The subsequent discing and harrowing pre- paratory to planting should aim at destroying the first crop of weeds, and to get the land firm with a fine surface tilth. It may be sown up to the end of December, but early November is considered the best time for the greater part of the Union. It is possible that it may be a profitable winter crop under irrigation. Linseed is often drilled, but more 314 CHArTBR XIX often broadcasted, and should not be planted deeper than chreequarters of an inch — consequently, if broadcasted, a weeder or very light harrow should be employed to cover the seed. For fibre 80 to 100 pounds, and for seed 30 to 50 pounds per acre, should be sown. Before sowing, the seed should be treated with formalin in the same way that wheat is treated for stinking-smut. Harvesting. — The crop takes 90 to 100 days to mature seed; it does not mature very uniformly, consequently judg- ment must be used to harvest when the percentage of capsules are ripe at one time. It is generally cut with a reaper and binder, or mower, then stocked, and, when thoroughly dried, threshed. Harvesting for fibre requires skill and care. The crop is hand pulled as soon as the capsules begin to turn yellow. It is laid out in swaths and allowed to dry. after which the capsules are " rippled off," or may be beaten off with mallets. After this it is graded and bundled for " retting," by the aid of which the fibre is ultimately freed. This consists in steep- ing the flax in water for five to fifteen dayo. thereby enabling certain biological processes to fiydrolise the tissue surround- ing the fibre. It is next dried, and the processes of " break- ing," " scutching," and " hackling," follow. In these the fibre is separated from the rest of the stem. It is then sorted, graded, and baled ready for market. About six hundred pounds per acre is considered a fair yield of fibre, and eight hundred pounds a good yield of linseed from a crop grown for the seed. The fibre crop, in addition to the fibre yield, gives about five hundred pounds of seed, much of which is immature. Improvement. — The crop in South Africa is likely to develop as a grain- rather than a fibre-cron. In Europe, varieties are distinguished as fibre and linseed types, the latter branching more, being heavier linseed yielders and having larger and heavier seed. For our conditions, however, grain varieties should be chosen, and selection from these should be made for size and weight of seed, allied with high total yield. Disease resistance can be acquired by selecting the seed from surviving plants in badly infested fields, and con- tinuing to do so each year. BUCKWHEAT. 315- Diseases. — Flax-Wilt {F. lini ISolley). — The spores are carried over in the soil, on dried stems, and by adhering to the seed. For this disease the formalin treatment and rota- tion are recommended. Flax-rust {Melampsora lini) is fairly common, but is seldom serious. The flax plant has no serious insect pests. EEFERENCES: Flax Cultivation." — South African Journal of Industries, November and December, 1919. Field Crops." — Wilson and Warburton. Cyclopedia of American Agriculture," pp. 293-302. Flax Culture."— U.S. Dept. of Agric. Bulletin 274. Resistant Seed Flax and How to Get it."' — North Dakota Bui. 23. BUCKWHEAT (Fagopyrum Spp.). Buckwheat has not been in general cultivation so long as the cereals, and in China it was not grown for human con- sumption until after the Christian Era. It is grown exten- sively in Europe and North America, and with success in most parts of South Africa. It occurs in the wild state in Manchuria. Description. — Buckwheat belongs to the Polygonacese, a family having angular, three-sided seeds. It has a strong central tap-root, no tillers, but many branches, somewhat tri- angular leaves, white flowers, and green to purple stems. There are three species in cultivation : — (1) Common or Japanese (F. csculentum). Vars. : Japanese, Silverhull, Gray. Key to V.\rieties of Common Buckwheat. Faces of grain slightly concave ; angles extended into very short wings — Common Gray. Faces of grain flat ; angles not extended into wings, grain small and plump — Silver Hull. Grain large and not so plump — Japanese. 316 CHAPTER XIX In Silver Hull the plant and seed are very small ; the seed is silvery in appearance, plumper, smoother, and heavier in weight per bushel, than Japanese or Gray. Japanese. — The seed is brown to black in colour, the plants and seed both large, and is generally the heaviest yielding and most commonly grown variety. Gray. — Is intermediate in character. (2) Tartary Buckwheat (F. tartaricum). — Sometimes called India wheat. It has a rough, wrinkled hull, small seeds, and wavy edges, small leaves and simple racemes. It is not much grown, but will succeed in higher and cooler alti- tudes than F. esculentum. (3) Notch-Seeded Buckwheat {F. emarqinatum) is culti- vated to some extent in India, but very little in other coun- tries. It is distinguished from F. escuUmtum and F. tar- taricum in having the angles of the smooth hull prolonged into wide, rounded wings. Buckwheat Grain. — Has a very heavy hull, which shows a tendency to split along the edges. The endosperm is softer and more starchy than in most wheats, and is low in fat content ; the flour is low in protein. Essential Ingredients of Buckwheat and its Products. (Hunt.) Grain. Water 12-6 Ash 2-0 Protein 100 Crude Fibre 8' 7 N.-Free Extract ... 64-5 Fat 2-2 50 to 60 per cent, of the grain is recovered as flour, 25 per cent, as middlings, and 15 to 25 per cent, as hulls. Uses. — The flour is used to a considerable extent as human food in the making of buckwheat cakes in Europe and America. The w^hole seed ground is used as stock food, and in those countries where flour is produced, the middlings, on account of their protein content, are looked upon as a valuable con- centrate. Cracked grain is used to a considerable extent by poultrymen, and on account of quantity and quality of the nectar in the flowers, it is very often grown solely for honey production. Flour. Middlings. Hulls. 14-6 12-7 10.1 1-0 51 20 6-9 28-1 4-6 0-3 4-2 44-7 75-8 422 37-7 1-4 7-7 0-9 BUCKWHEAT. 317 The straw is of little feeding value. Because of its quick and heavy growth, often on relatively poor land, it is one of the best non-leguminous plants for green-manuring, and, in addition, a good smothering crop. Climate. — Buckwheat is a summer annual. x\s a green manure it will give good growth during the summer in most (.'ountries. During hot, dry spells, it fails to set seed but, being to a certain extent indeterminate in growth, this feature is often overcome. It is better, however, to plant accord- ingly, i.e., so that the flowering period does not synchronise with the hottest months of the year. In the greater part of the Union planting about the middle to the end of January is best for seed production ; flowering then takes place in February, and continues for several weeks. The seed com- mences to mature 56 to 75 days after sowing, and thus buck- wheat is one of the quickest in maturity of the grain crops. On account of this feature it is one of the most suitable of catch crops, and should be chiefly grown for this purpose in South Africa. Soils. — It will do well on most soils, but does better than the cereal crops on thin and sour soils. Except as a catch crop, it should not be grown on good soils, as other crops will be found more prohtable. On rich soil it lodges very readily, but does well on newly " braaked " soil, i.e., virgin soil. Cultural Methods. — Fair crops will be grown with less soil preparation than for the cereals, but it naturally responds well to good soil cultivation. The seed may be drilled or broadcasted at the rate of forty to fifty pounds per acre. It should be harvested when the majority of the seed has matured, and as it shatters readily, this operation in extremely hot weather should be avoided. If cut in the early morning, when still damp with dew, excessive shattering can often be minimised. As the straw is still green when the crop is harvested, it must be loosely cocked and, on account of heating, it is often better threshed from the field. If stacked prior to threshing great care is necessary to prevent over- heating. It can be threshed with an ordinary wheat thresher, having the concave adjusted so as not to crack the grain. It is a crop apparently little affected by diseases or insect pests. 318 CHAPTER XIX SUNFLOWER (Helianthus annus). This is a summer annual, grown chiefly for the seed, which is used for feeding to poultry and for the oil contained, .and to a limited extent for silage. It is a native of North America. Varieties. — (1) Common. — Heads 8 to 16 inches in dia- meter, seed grey, brown or striped. (2) Mammoth or Giant Russian. — Heads 15 to 20 inches in diamete, seeds about half an inch long, with black or brownish stripes, though sometimes they are all white. Con- sidered one of the best varieties for oil-production. (3) Black Giant. — Produces heads 16 to 22 inches in dia- meter, with black seeds fin. in length. Soil and Climate. — Its soil requirements are very similar to those suited for maize. It is considered to be a heavy feeder and exhaustive on soils. It requires plenty of sun- shine, and is more resistant to drought, alkali and frost, than maize. Cultural Methods. — The land should be prepared as for maize. Plant the seeds 1 to 3 inches deep in rows 3 feet to "3 feet 6 inches, and 18 to 24 inches apart in the rows ; eight to fifteen pounds of seed are required per acre. It is best to sow thickly and then to thin out when the plants are about six inches high; this is, however, only practicable where labour is cheap and plentiful. It has a tendency to branch, and if large heads are to be produced, all lateral branches should be cut off ; this should be done when the plants are about three feet in height. The plants require a long growing season, and should be planted in November, except in the Low veld, where seed could go in as late as December. Harvesting. — The heads should be harvested before they are fully matured. This prevents loss through shatter- ing or from birds. If the crop is small, the heads may be harvested as they ripen. They are then dried as quickly as possible in the sun and threshed. Threshing is often done by flail, but where large amounts are handled the ordinary maize thresher, suitably adjusted, can be successful/ly employed. Small meshed wire netting, suitably stretched on a frame, and the heads rubbed over this, will often prove serviceable. SUNFLOWER. 319 The seeds are afterwards dried in the sun and then, where possible, run through a winnower. A bag of seed weighs about 100 lbs., and ten bags per acre is considered a good yield. Uses. — (1) The seed is used principally for poultry, but forms a valuable part of the ration for sheep, pigs, and other livestock. (2) Silage. — This has been tried in the United States, and as a mixture with beans and maize is said to give good returns. In a recent publication^ Dr. Shutt concludes " that sunflowers make a satisfactory, acceptable soiling and silo crop, in districts in which the season is too short, the nights too cool, and the rainfall insufficient for the best results with maize. . . . The exact stage at which to obtain the largest amount of digestible dry matter per acre is not as yet known, but would appear to be when about 10 per cent, of the plants are in bloom. If left much later, the increase in dry matter appears to be more than offset by the marked increase in fibre content, leading to a decided decrease in the digestibility of the silage." Composition ]\Iaize and Sunflower Silage. Crude Crude Water. Protein. Fat. Carbos. Fibre. Ash. Sunflower cut when 10 per cent in bloom... 75.67 3.43 1.24 10.17 6.22 3.27' Sunflower seeds fully formed 52.31 5.06 2.42 24.75 10.16 5..30' Maize 73.7 2.1 0.8 15.4 6.3 1.7= From these analyses it will be seen that sunflower silage cut at the right stage is very similar in composition to maize silage, but contains a slightly higher percentage of crude pro- tein, fat, and ash, than the latter. The Grootfontein School of Agriculture claims excellent results from ensilaging sunflowers. (3) The largest production is in Russia, where the crop is grown to a large extent for oil. The oil is said to be superior to both almond and olive oil for table and cooking purposes, and is also used in the manufacture of soap and candles, and for lighting. 820 cbapter xix Analysis by Transvaal Department of Agriculture. Husk ... 43"43 per cent. Kernels 56-57 Percentage oil in keruela ... ... 36" 7-2 ,, Percentage oil m seeds 20'77 ,, After pressing out the oil from the seeds, a residue is left in the form of a cake, which is of high nutritive value, and said to be quite equal to that of linseed and cotton-seed cake for feeding dan-y cattle. Conclusion. — It is a crop for intensive agriculture where labour is cheap. Whether it would be profitable when grown on a large scale in South Africa is questionable. It thrives in parts where maize succeeds, and is a much surer crop in tunes of drought. REFERENCES: " Seasonable Hints," July, 1921. — Dominion Exp. Farms. " Feeda and Feeding." — Henry and Morrison. PUMPKINS {Curcubita pe'po). KAFFIR AND STOCK WATERMELONS (Citrullus ruUjaris). These are grown for human consumption and for stock food. Certain sj^ecies of the genus Curbuhito, and all the kaffir and stock watermelons are indigenous to Africa and South Africa. Pumpkins. Description. — Pumpkins arc summer annuals, monoe- cious ; of two distinct types. (1) Table. — Medium size, generally flat, with thick flesh and fine-grained. The seed cavity is small in proportion to the size. (2) Cattle. — Large size, somewhat spherical in shape, flesh coarse, and sometimes with woody lumps. The seed cavity is large in proportion to the size of the pumpkin. They cross-pollinate readily within the genus, and with some of the other genera belonging to the Curciibitacece. Cattle pump- kins will weigh up to 120 pounds. pgMPKINS AND MELONS. 321 Cultural Methods, Etc. — Pumpkins are very suscep- tible to frost, and should not be planted until all danger of frosts has passed. Under irrigation they are preferably planted from September to October, and on dry lands in November. They do well on moist soils, except heavy clays. Manuring, particularly with stable manure, is advisable. The manure may be applied in hills or on a large scale in strips across the land, the rows being along these strips. They are planted 10 by 10 feet, four or five seeds ner hill — these are subsequently thinned out to two or three plants per hill. About two to three pounds of seed is required per acre. The crop is better grown alone and not in competition with maize. When well started, pumpkins resist drought fairly well. The fruit stalk should not be broken off, as this en- courages decay. They should be harvested about June, after the killing frosts, and stored in a dry place. To preserve pumpkins for table use they are sometimes stored in pits covered with sand. Properly stored, they keep well until October. Thick-skinned varieties keep best. Stock pumpkins yield from 40 to 50 tons per acre. Sliced up, they form an excellent addition to the winter feed for sheep, cattle and pigs. Stock Melons. Stock varieties of melons have been devoloped in the United States of America, some of which have not yet reached South Africa. These, like the Maketaan and Tsamma (common species found in the dry parts of the Union, e.g., the Kalahari), are non-saccharine. The Tsamma weighs three to four pounds; Maketaan considerably more, while some of the stock melons weigh up to 75 pounds. The cultural methods are somewhat similar to those re- quired for pumpkins. They are exceedingly drought-resistant, giving heavy yields in very sandy soil and under very low rainfall. " The Maketaan (Mammoth and Fraserdale) are now extensively grown in different parts of the Karroo, where, owing to scanty rainfall, irrigation is needed for all other kinds of crops." They mature about April to May, and if carefully stored will last to the end of September or later. Dr. Juritz reports a yield of 300 tons per acre ! 322 CHAPTER XIX Composition (Dried). Water. Protein. Fat. Carbos. Fibre. Ash. N.R. Tsamma 9-40 5-77 48-40 27 -79 8-24 1 : 6-6 Stock Melon 7-97 3-77 58-90 2-2-0-2 7-34 1 : 8-4 Pumpkin 90-5 1-3 0-4 5-2 1-7 0-5 The seed of the Maketaan contains 15 to 19 per cent, protein and 20 to 23 per cent. fat. Four to five per cent, of the melon is seed. The green weight contains 92 to 94 per cent, of water. Pumpkins and melons must be looked upon as valuable in supplying succulence for winter feeding. They are ex- tremely bulky, and should not be used as a complete ration in themselves. If maize silage is available, the silage should be kept for September, October, and November, while the pumpkins and melons are being fed during the winter months. REFERENCES: " Notes on Some Indigenous and Other Fodder Crops." — Science Bul- letin No. 6. — Juritz. " Botany of Crop Plants."— Bobbins. " The Farmers' Handbook." — New South Wales Dept. of Agric. Encyclopaedia of American Agriculture. CHAPTER XX. MINOR CROPS Since most of the crops dealt with in this chapter belong to the leguminosae, the following key to the principal genera, given by Robbins/ may be of use : — Plants with tendril-bearing leaves : Calyx lobes leafy, stipules large, rounded — Pisuvi (pea). Calyx lobes not leafy, stipules mostly small, pointed. Style slender, bearded at the tip — Vicia (vetch). Style flattened, bearded along inner side — Lathyrus (vetchling). Plants without tendril-bearing leaves : Leaves palmately three-foliate — Trifolium (clover). Leaves pinnately three-foliate, rarely five to seven- foliate. Flowers small, many in a cluster. Flowers in slender spike-like racemes — Melilotus (sweet clover) . Flowers in heads or short spikes — Medicago (lucerne). Flowers medium to large, few in cluster. Pods smooth, mostly large. Keel of corolla spirally coiled — Phaseolus (bean). Keel of corolla merely incurved — Vigna (cowpea). Pods hairy, small — Soja (soy bean). Leaves pinnate, with two pairs of leaflets — Arachis (pea- nut). FIELD BEANS (Phaseolus spy.). Beans belong to the leguminosae or pea family of plants. They are either annual, biennial or perennial; although most of the common varieties in the Union are annuals. The most characteristic features of this genus are the pea-like flowers, 323 324 CHAPTER XX the pods and the nodules on the roots. Because of their bene- ficial effect on the soil, their cultivation might well be extended. Climatic and Soil Kequirements. — Beans are hot weather crops, and for that reason they should not be planted until all danger from frost is over. Any good agricultural soil thoroughly prepared will produce beans. They seem to thrive best, though, on deep loam soils, not too sandy in nature. Very heavy brak and water-logged soils should be avoided, as these are decidedly unfavourable for the production of these crops. Soils containing too much organic matter, such as are often found in vleis, are also undesirable, as they stimulate vegeta- tive growth at the expense of seed production. When grown on dry lands the preparation of the seed-bed should aim at the production of one retentive of soil moisture. Cultural Methods. — For successful bean production, the proper preparation of the seed bed is of utmost importance. The land is best ploughed in winter and disced before the beans are planted in the spring. The time of planting will vary with the locality as well as with the variety planted, whether early or late maturing. Under average South African conditions probably the best period for sowing this crop is during the months of November and December, when the heavy summer rains coincide with high temperatures. The best method of planting beans is with an ordinary maize planter fitted with plates that will allow the beans to pass through regularly. A small grain drill with some of the holes stopped up to get the rows the correct distance apart could also be used advantageously. The rows are generally made about 2 to 3 feet apart and the seeds spaced 6 to 12 inches in the row. On dry lands the spacing must necessarily be wider than under irrigation. In no circumstances should the seed be placed deeper than 2 inches, otherwise the seedlings will have difficulty in reaching the surface. The rate of plant- ing varies with the size of the bean ; about 10 lbs. of Tepary beans, 30 to 40 lbs. of sugar, and 50 to 60 lbs. of white kidney beans will be found to be the right quantity to plant per acre. The crop on a well prepared seed-bed will require three to four cultivations. Harrowing is sometimes necessary just before the beans begin to appear to break the soil crusts and to destroy new seedlings that may have germinated. Where a very good stand has been obtained, a second harrowing after the plants are up may be of use ; this operation is best carried out when MINOR CROPS. 325 the young seedlings are wilted; otherwise, being too brittle, a large number will be broken off. Cultivation should be com- menced soon afterwards, and should continue until the vines meet and thus make inter-tillage impossible. Harvesting should start when the majority of pods have turned colour, and before the oldest have started to shatter. Where there is any danger of shattering, the crop is best cut at a greener stage and the handling done during the early morning hours when the crop is moist from the dew. The crop is generally pulled or cut by hand, but where large acreages are grown, they are most economically harvested with an implement called a bean cutter, the essential feature of which is a pair of sharp knives, about three and a half feet in length, mounted on a sled, from which they should stand inward and slope backward at an angle of 66 degrees. The sled straddles two rows and deposits the plants in a windrow, where they are left until dry enough to be put up in cocks before being threshed. In South Africa thresh- ing is mostly done with a flail or by trampling with animals. Grain threshers have thus far proved unsatisfactory in that too many of the beans get cracked. In America special bean threshers are used and are reported to give every satisfaction. Being a soil renovating crop, it should, where desirable, be included in rotations. It is undoubtedly one of the best cash crops on dry lands as well as under irrigation. On the former it can precede maize, and on the latter wheat in the rotation. Production and Yield. — The acreage under this crop in the Union, according to the 1918 agricultural census, was 30,474 morgen, which gave a total production of 256,472 muids of 200 lbs. each. Thus the average acre yield is about three to four bags, though much higher yields are often obtained. Uses. — Beans are used in large quantities dried, and in the pod as " green beans," They are also to a limited extent used as stock feed when ground, and the straw makes a valu- able hay for all classes of livestock. On account of their high protein content, all parts of the plant constitute an important portion of rations which may include them. Varieties in South Africa. — Beans belonging to the sugar group are those in greatest demand and fetch the highest prices. The best varieties of these are Painted Lady and Port Natal. White varieties such as Large White Kidney, Large and Small Haricot are also popular and sell well. Of the col- 326 CHAPTER XX oured varieties the Red Canadian Wonder is probably the most outstanding. VELVET BEAN (Stizolobium deeringianum) . This plant is often called Florida Velvet Bean because of its early cultivation there. It is a vigorous growing summer annual, having much branched twining stems which may reach a height of 20 feet and upwards. The dark purple flowers are borne on slender pendent racemes. Two distinct types of pods are j)roduced, one covered with a dense black velvety pub- escence, as in the Florida and Georgia varieties, and the other type has a white to greyish pubescence, e.g., Chinese and Yokohama varieties. The latter shatters badly. The pods of the commoner types are short, 2 to 3 inches in length, some- what constricted about the seed, and contain most commonly three to five grey or mottled seeds, although white and black seeded varieties are also knowm. Early and late varieties are found. The Florida variety is the one commonly grown in South Africa, although a white-seeded variety is found in Zout- pansburg. The velvet bean is considerably later in maturing than cowpeas (kaffir beans) and soy beans usually grown in the Union. An early variety more suitable for many districts might be produced by crossing Florida and Chinese. At present it is so late in maturing that it produces seed only in the Lowveld, where it is grown to a limited extent. It should be sown at the rate of 30 to 50 lbs. per acre when grown for green-manuring or as a smother crop to be harvested for fodder. In America it is sometimes used to smother out quick grass. On account of its entangled growth it is extremely difficult fo harvest. The stems are generally cut by means of a spade. If used for hay, the crop must be harvested before any of the pods mature. Its use for silage when grown with maize is advocated by some, and in the United States it is sometimes pastured off for cattle and pigs. MUNG BEAN (Phascolus aureus). This is an erect summer growing annual legume introduced from India. In some localities it has given excellent results, promising to replace cowpeas in South African agriculture. In some respects it resembles the soy bean, in others the cowpea. The seed, small and of a green colour, makes an excellent soup, but is very subject to depredations by weevils. Being of an MINOR CROPS. 327 erect growth, the plant can be harvested more easily than the cowpea, and for the same reason can be more readily ploughed under as a green manure. THE FIELD PEA. Piper says : — " It is customary to distinguish agricultur- ally between the garden pea {Pisum Jiortense) and the field or Canada pea {Pisum arvense), but whatever characteristics are used, there are all possible inter-grades in the long series of cultivated varieties. In general the term field pea is restricted to those having somewhat angled, brown to black or marbled or speckled seeds and coloured flowers ; garden pea to those having white flowers and round, yellow seeds. But several varieties are used both for vegetables and for forage." In South Africa field peas are looked upon as winter rather than summer annuals, since their growth during the hot months is extremely poor. They are fairly resistant to drought.. Except in the winter rainfall area, however, they must be grown under irrigation. Description. — -They are usually decumbent, pale green and glaucous; the leaves are pinnate, with one to three pairs of leaflets ; numerous tendrils ; having stout axillary preduncles bearing each one to three flowers. Those seeds, having a very angular form, owe their shape to a higher sugar content and consequently greater shrinkage when drying. " The colour of the seeds when of a single tint may be yellow, pea green, brown or black. Yellow or green seeds may be marbled with brown or speckled with blue, black or brown, or both marbled and speckled. The embryos are yellow in yellow seeds and green m green seeds." Numerous varieties are found. They are best sown with oats, but will do well with rye. In general they do well when used for the same purposes as those described for the vetches. In mixtures a quantity of peas equal to that of the cereal should be used. When grown for seed they must be planted early enough to ensure the setting of pods before the w^arm summer weather arrives. Unlike the vetches, when grown for seed they are badly attacked by the pea weevil (Laria pisorum or BrucJius pisorum) , which lays its eggs on the devel- oping pod ; the larva hatches and burrows into the young seed and remains for a considerable period in the mature seed. 328 CHAPTER XX THE CHICK-PEA (Cicer arietinum). This is a bushy, hairy winter annual which has grown well in those parts of South Africa where it has been tried. Although it seeds heavily and the seeds are weevil-resistant, there appears no reason why its cultivation as a field crop should be advo- cated, since owing to an acid secretion from glandular hairs with which the plant is sparsely covered, it is unpalatable to stock and, moreover, is said to be poisonous to cattle and horses. In India it is known as " gram." The seeds resemble the pea and have a beak-like projection near the hilum. THE GKASS-PEA {Lathyrus sativus). This has been tried at experimental stations and is another winter annual having no decided characteristics to warrant its cultivation in South Africa. The seeds, which are wedge- shaped, are used for human consumption, but if eaten continu- ously cause paralysis. The seeds are also immune to weevil attacks. The stems are flattened and more slender than those of the ordinary pea ; the leaves consist of one or two pairs of narrow grass-like leaflets and have branched tendrils ; the flowers are w^hite and solitary ; the pods are about 1 inch long and 1 inch wide, flat and contain three to four seeds, which are generally yellow or yellowish-green. THE VETCHES. While a number of plants belonging to various genera are called " vetches " in different parts of the world, the term " vetches " should, however, be used only of those plants be- longing to the genus Vicia. There are four species commonly met with in South Africa, viz. : — V. sativa. — Common Vetch or Tares or Spring Vetch. V . villosa. Hairy or Winter Vetch. V. angusti folia. — Narrows-leaved Vetch. V. fabia. — Broad, Windsor or Horse Beans (Boer boontjie). As field crops, V. sativa and villosa are the only ones of im- portance in the Union. Angustlfolia is frequently found as a weed and fahia is commonly grown in gardens as a vegetable. V. sativa is a winter annual in South Africa, having stems 2 to Plate XXV SECTIONS OF YOUNG MANGEL. SHOWING RINGS OF VASCULAR BUNDLES. Plate XXVI PLOT OF SUNFLOWERS AT THE TRANSVAAL UNIVERSITY COLLEGE FARM. Plate XXVII MUNG BEAN (PHASEOLUS AUREUS). J'l.ATE XXVIII OLD 5IAN SALTBUSH (ATRIPLEX NXTMMULAI; 1 A ) Al i . H( m 1 1 1 i )\ I K I X Si niiiiL OF AGRICULTURE. (COURTESY UNION DEPARTINIENT OF AGRICULTURE). SPINELESS C.-VCTUS. (COURTESY UNION DEPARI MENT OF AGRICULTURE). MINOR CROPS. 329 3 feet in height, which generally branch from near the base. The plant when unsupported is decumbent in habit. The leaves are numerous and compound, terminating in tendrils. The leaflets are oblong, square at the end and decidedly muc- ronate. The flowers are in pairs at the base of the leaves, gene- rally purple to rose-coloured, but are somteimes entirely white. The pods are brown, each containing from four to five, usually grey or marbled seeds which are readily shattered at maturity. Vetches are seldom cross-fertilised. This species is indigenous to Europe, Asia and Northern Africa. V. villosa. — This is also a winter annual, the stems of which reach a length of about 12 feet. It grows from 2 to 4 feet in height, winding and trailing in all directions, like Common Vetch, from which it is easily distinguished, even if no flowers are developed, by its hairiness, the whole plant being covered with long, soft, spreading hairs, which often give it a white woolly appearance. The leaves are compound and the leaflets gradually taper towards the apex. The flowers are purple to pale blue in colour, borne on long peduncles, and are smaller than those of sativa. The pods are smooth, pale- coloured, containing two to eight small black globose seeds, velvety when fresh. It is hardier to cold than sativa and its early growth is much slower. It has a deep and much branched rooting system. This species is indigenous to Europe and Asia. Habits of Growth. — Although closely related, the development of peas and vetches is very different. The main stem of the pea plant grows during the whole life of the plant, but the branches are less vigorous. In a vetch the main stem soon stops growth and strong lateral branches are developed from the base. In this respect their winter annual character- istics are shown, since in the colder parts they start growth later in the season, remain stationary during winter, and com- plete development during the summer. The seedling staj?e, particularly in the case of Hairy Vetch, is very disappointing : however, once active growth commences, the ground is soon covered and a dense deep mat is formed. When used as hay croys they are always grown in con- junction with oats, barley or rye, as without these harvesting with a mower w^ould be practically impossible on account of their prostrate and entangled habit of growth. In northern countries sativa is generally sown in the spring and villosa in the winter. In South Africa, however, little 330 CHAPTER XX difterence need be made, except that in mixtures Hairy Vetch should preferably be used with late varieties of oats and barley. Cultural Methods. — A fairly compact seed-bed is required. They can be sown from the end of February (Hairy Vetch) to the end of July (Spring Vetch). Fifteen to twenty- five pounds of vetch are generally grown with forty to sixty pounds of oats, barley or rye. If the vetch is grown as a green- manuring crop, then thirty to forty pounds of seed is used per acre. Practically all the seed is imported and is expensive. For this reason thinner seedings are advocated. The Common Vetch shatters its seed readily and in consequence is sometimes troublesome as a weed in winter cereals. As a rule vetches prefer sandy and light types of soil to heavy ones. The Common Vetchs like lupines are injured by heavy applications of lime ; on the other hand. Hairy Vetch prefers calcareous soils and is quite the most resistant to alkali of all field legumes and is besides fairly drought-resistant. Unlike cowpeas, the vetches may be sown quite deeply without injury, because the coty- ledons . remain where planted, the plumule becoming much elongated. Two inches, however, is the optimum depth for sowing. Experience in America points to the necessity for soil inoculation ; however, in South Africa on fields where winter cereals have been grown for any period, the necessity does not arise, since inoculation has probably been accomplished by vetches as weeds in these crops. When grown for seed, both species can be grown, with a variety of oats which takes about the same time to mature. When fully matured, the mixed crop is harvested and threshed with the ordinary grain thresher, which will easily separate the seeds ; the straw provides a fairly good feed. If grown for seed purposes, the quantity of vetch seed in proportion to the oats should be reduced and the mixture sown on poor soils in preference to rich soils. Uses. — Under irrigation and in those parts having a winter iTainfall, the vetches and field peas might well play a more im- portant part. When grown alone they make an excellent green- manuring crop of winter growth, and are also very useful as a pasturage. As a hay crop in mixture they are easily harvested, assist in maintaining the fertility of the soil, and, being extremely nitrogenous and palatable, they increase the feeding MINOR CROPS. 331 value of the crop with which they are grown. When grown with oats the yield varies from 1^ to 3 tons of hay per acre. The vetches are extremely free from insect or fungus pests. SAINFOIN iOnohrychis vici(sfolia.) This is a perennial with a strong tap root and numerous erect stems, which reach a height of 1 to 2 feet. It has com- pound leaves and an inflorescence that is spikelike, long and thin, with showy pink flowers. Sainfoin has been cultivated in France for 400 years. It prefers calcareous soils of open texture and is very drought-resistant. Piper cites Lawson, who claims that the plant may live for 100 years. It does poorly in competition with weeds and is generally sown at the rate of 60 to 100 lbs. per acre. As a pasturage it is excellent and has not been known to cause bloating. It w^ould appear to have possibilities in South Africa, where calcareous soils are found, to furnish grazing in July, August and September and hay during summer. SULLA OE SPANISH SAINFOIN (Hedysarum coronarium). This is a perennial legume which has been tried at the various experimental stations in the Union. It prefers much the same soils as sainfoin, but is not so drough resistant and vigorous in growth. The flowers are red and the compound leaflets are less in number than those of sainfoin. The plant is greyish in appearance and the seed is diflicult to germinate. BUKNET (SANGUISOEBA MINOR). This is a deep-rooted perennial herb making an excellent winter growth in South Africa. The leaves are ovate and the leaflets deeply toothed. The stem is about 1 foot long and bears a few heads of light green or purplish monoecious flowers. It is sown at the rate of 30 lbs. per acre. Burnet, or Sheen's Burnet as it is commonly called, is fairly hardy and drought- resistant, and, like sainfoin, prefers calcareous soils. It is not very palatable, but is looked upon as an excellent tonic, espe- cially for sheep during the winter months, and will furnish good grazing under very adverse winter conditions. While the sainfoins and Burnet make excellent growth, the stands readily become sparse in competition with weeds or if hard soil surfaces are formed. 332 CHAPTER XX KUDZU VINE {Pueraria thiinbergiana). A perennial legume indigenous to Japan. It has large leaves with very woody older vines. The purple-red flowers are borne in racemes. The pods are covered with short brown hairs containing numerous speckled seeds. In South Africa it is only now being tried as a field crop, although it has been used as an ornamental plant for some years. The vines will attain a length of 60 feet, and it seems to be drought-resistant and to do well even on the poorest of soils, although clay loams are preferred. The growth from seedlings is slow, and, moreover, the seed germinates very poorly under ordinary treatment. It is best propagated by roots, obtained from the prostrate vines which root at their joints. These should be planted 9 feet by 9 feet. Heavy crops are obtained only in the third season. The leaves are extremely persistent and little loss is experienced in hay- making, although harvesting is difficult. Its function would seem to lie in grazing, where it can be employed in fields not suitable for other crops. THE CLOVEES. Various species oiTrifolium have been tried privately and at all the experimental stations in South Africa with very meagre success. Species belonging to the genus Melilotus, however, grow very well, but have not as yet become popular. Generally the climate in South Africa is unsuited to the clovers, and in parts where the climate is not wholly unfavourable the absence of the specific nodular organisms seems to be the factor limit- ing their growth, since in one or two localities in the Western Province, where persistence has been shown in soil inoculation, successful stands have been obtained. Bed Clover {Trifolium pratense). — Its value in the northern hemisphere is indicated by Piper, who says : " Ked Clover is the most important of all leguminous forage crops, both on account of its high value as feed and from the fact that it can be so well employed in rotations." In North America five times as much Pod Clover is grown as lucerne ; in fact it forms the basis of farming in many countries in Europe and North America, and is also extensively grown in Chili and New Zealand. Eed Clover is mainly biennial. In contrast to lucerne, the primary root contracts as it grows older, resulting in a deep-set crown. The stems spring from buds in the crown MINOR CROPS. 333 in a manner very similar to lucerne. The inflorescence is a dense liead about an mch in diameter when fully developed, usually red in colour, but may be white. The oblong leaflets are gene- rally marked with a white spot of varyitfg size and shape. It is completely self -sterile ; cross pollination is effected by insects, chiefiy bumljle bees. The pods contain only one seed each and the flowers are persistent. The seeds may be yellow or purple, and some may be bright at one end and dark at the other. Mammoth Ked or Cow Grass (T. pratense var. perenne) is a coarser perennial variety of Eed Clover. Red Clover is essentially a crop for humid parts where temperatures are not very high. It has poor drought-resisting qualities, and since lucerne can generally be grown on irrigable land which will grow Eed Clover, there seems to be no advan- tage in employing it on such fields. It is, however, not so exacting in its soil requirements as lucerne, and does best on well drained calcareous soils. It is probable that in suitable areas in parts of South Africa having winter rainfall and on inoculated soils, if sown in Feb- ruary, March and April, it could be grown without irrigation, giving a good hay crop before the hot and dry summer months set in. Clover should be sown at the rate of 8 to 12 lbs. per acre. It is often sown with grasses, giving two hay crops during the first season and providing with the grasses, excellent grazing the following year. The hay is easier to cure and handle than lucerne hay. If cut at full bloom and before the heads com- mence to turn brown, it gives hay of the highest feeding value. When grown continuously in the same soil, the crop eventually becomes unthrifty and the soil is said to be " clover-sick." A great many theories have been advanced to explain this, but none has been proven. Nearly 50 per cent, of the plant at full bloom consists of roots, which to a great extent explains its remarkably beneficial effect on the soil. Crimson Clover (T. incarnatum) is an annual adapted to somew^hat hotter areas than Red Clover. It is very poor in resisting drought and there seems to be no outstanding reason why its cultivation in South Africa should be encouraged. It is distinguished from T. pratense by its longer inflorescence of a rich scarlet or crimson colour. The head has a bluish green tint before flowTring. 334 CHAPTER XX White or Dutch Clover (T. repens) is a low-growing, shallow-rooted perennial species havnig adventitious roots, bearing small pure white flowers on long fibwer stalks from the lower part of the stem. It is especially adapted to rather moist, warm climates, and does fairly well on comparatively water-logged soils. It is an excellent legume for pasturage and is nearly always included in pasture mixtures in Europe and America. When grown alone poor results have been obtained in South Africa, but Melle has found it to grow excellently in conjunction with kikuyu grass on well limed soils. At the Experimental Farm, Potchefstroom, it is affording good pas- turage together with paspalum. Alsike Clover (T. hybridum). — It is a fairly erect growing glabrous perennial, having white to pinkish flowers — white when young, pinkish later on, borne on the terminals of branches. The seeds are small yellowish-green, black and greenish-black in colour. It is shallow rooted, poor in drought- resistant qualities, and will do fairly w^ell on soils too poorly drained for Ked Clover. It thrives in cool climates having abundant moisture. Trials at the experimental stations in South Africa have not shown it to be suitable to our conditions. Berseem (T. alexandrinum) is a white flowered annual pre- ferring higher temperatures than the other clovers commonly grown. It is extensively grown as a winter irrigation crop in Egypt, and as such might find a place in South African agricul- ture. Subterranean Clover (T. suhierranece) is a perennial grown in Australia, having rhizomes, and which may prove of use in South Africa, since it is supposed to be more drought-resistant than the other species of Trifolium. SWEET CLOVERS (Melilotus spp.). W^hite, Sweet or Bokhara Clover (M. alba or leucantha) is an erect biennial, having white flowers. It grows 3 to 4 feet the first year, and may reach a height of 6 to 9 feet the follow- ing year when it flowers, the racemes being 3 to 12 inches in length. The stems are coarse and very woody close to the ground. Yellow Sweet Clover (M. officinalis) is a yellow flowered biennial species of earlier and more slender growth than M. alba; it is also less leafy and smaller in size. MINOR CROPS. 335 There are several annual species as well as an annual selec- tion of M. alba, namely, Hubbam Clover, wbicb makes rapid growth under South African conditions, and has attracted a great deal of attention lately. The Sweet Clovers contain a bitter substance called cumarin, which renders them unpalat- able to stock, a fact which has restricted their cultivation. Once accustomed to it, though, stock thrive on it. Agriculturally, M. alba is much the most important. It grows readily on a variety of soils, heavy and light, rich and poor, well drained and poorly drained. In South Africa it enjoys the reputation of doing well on poor sandy soils — a hap)i \ fact, since being an excellent green-manuring crop, it might well be utilised in renovating worn-out sandy soils. It is drought and alkali-resistant to a high degree. A fine seed bed is required, and 15 to 20 lbs. of seed are used per acre. American experimentalists consider it, on account of its vigorous root system and quick decay of the whole plant, to be one of the best crops for green-manuring. The young growth is less bitter than the older growth and it makes good grazing for stock that will take to it. As a hay crop in South Africa it is difficult to see why sweet clover should be superior to the erect growing types of cowpeas. It is highly esteemed by bee-keepers. THE SWEET POTATO (Ipomcea batatas). The original home of the sweet potato is in the West Indies and Central America. It belongs to the Convolvulace^ or the Morning Glory family, and is a perennial with very much thickened roots, which constitute the edible portion. It seldom produces flowers and rarely, if ever, matures seeds. When in favoured locahties, seeds are produced and planted, new varie- ties may thus be originated. The classification of varieties is based on the shape of the leaf, which is round, lobed or notched. They may also be divided into two groups upon the basis of the amount of w^ater and sugar present — (1) dry sweet potatoes are ones in which the flesh is dry, mealy and yellow; (2) "yams" are sweet potatoes of which the flesh is watery, rich in sugar, soft and gelatinous when cooked. Climatic and Soil Eequirements. — For maximum pro- duction it requires a fairly long growing season, free from frost, such as is found along the southern coast belt of the Cape Pro- vince and in the Lowveld areas of the Transvaal Province and 336 CHAPTER XX Natal. It is adapted to fairly warm temperature and a medium rainfall, or, in the absence of the latter, a moderate number of irrigations. Although the crop is grown on a wide range of soils, it seems to thrive best on sandy loams with a clayey well-drained sub-soil. It has the reputation of growing on very poor sandy soils, especially along the coast, but for profitable returns it is best grown on soils of fairly high productiveness. Excessive applications of stable or kraal manure tend to produce too much top growth and too little root formation. Cultural Methods. — Sweet potatoes are generally grown from slips, from the roots, or more commonly from vines. The latter is the method practised to the largest extent in South Africa. The best practice, though, is to sprout the roots in warm sand and then to remove the sprouts for setting in the field (as they become large enough). As the roots continue to sprout for some time, a comparatively small number of roots will supply sufficient plants for a fairly large sized area. Where the crop is propagated by means of vines, these are cut about 1 foot long. The crop is ordinarily planted by hand on flat or unridged land in rows two to three and a half feet apart with plants spaced fifteen to eighteen inches in the row. Where the land is not well-drained it is advisable to plant the crop on ridges, as described for potatoes. In the case of vines three-fourths of the cuttings should be buried below the ground and care should bo taken to plant them in soil which is fairly moist or otherwise irrigation must be resorted to. The land intended for this crop should be ploughed some time in advance of planting so as to give it time to settle. It should subsequently receive a cultivation or disc-harrowing, to put it into good tilth before the plants are set out. Analyses have shown that sweet potatoes take large pro- portions of potash from the soil, as well as fair quantities of the other elements of plant food, and on that account the crop should not be grown continuously on the same lands for any length of time. Eotative cropping is as necessary with this crop as it is with ordinary potatoes, and when the soil shows signs of exhaustion the necessary elements of plant food required should be supplied in the form of artificial fertilisers : " A fertiliser containing 2 to 4 per cent, of nitrogen, 8 per cent, of phosphoric acid, and 8 to 10 per cent, of potash has MINOR CROPS. 337 given very satisfactory results.'" It also follows well after a green-manuring crop, especially on poor sandy soils lacking in organic matter. The cultivation is no different to that given to most other cultivated crops. A one-horse cultivator is generally em- ployed for stirring the soil between the rows and to prevent a hard crust from forming. This operation is discontinued as soon as the vines commence to cover up the space between the rows, and after some loose soil has been worked up towards the plants. Under normal conditions in South Africa the crop may be lifted any time during the winter months, after the vines have died. Where the winters are very severe and the roots likely to be frosted in the ground, they should be lifted and, as their keeping qualities are poor, graded and sent to the market without delay. Yield and Production. — The average annual production of the Union, according to the 1918 Agrciultural Census, was as follows : — Province. Cape of Good Hope Natal Transvaal Orange Free State .. Acres. 12,162 3,643 4,411 176 Production. 46,089,450 lbs. 12,290,850 ,, 10,529,250 ,, 231,600 ,, Yield per acre. 3,790 lbs. 3,374 ,, 2,387 ,, 1,316 „ Total 20,392 69,141,150 lbs. Av. 3,390 lbs. From the above is seen that the average yield per acre is 3,390 lbs., or, approximately, 22 bags of 153 lbs. each, as compared with 2,200 lbs. per acre of ordinary potatoes. In the sweet potato belt of the Cape Province — namely, in the Districts of Oudtshoorn, George and Knysna, the yield per acre is considerably higher. Uses. — It is chiefly used as food for man, but in some parts it is considered excellent stock food, especially for pigs. Besides these two uses, alcohol is manufactured from it in certain countries. CHICORY (Chicoriiim intijhus). Chicory belongs to the CompositfP, or thistle family. It is a perennial, with a fleshy tap-root about one foot in length. Climatic and Soil Requirements. — This crop can be grown either as a summer or a winter, dry-land or irrigation 338 CHAPTER XX crop. It is fairly drought and frost-resistant, although for its highest production, other factors being favourable, it requires a good rainfall, or in its absence a few thorough irrigations. Like other root crops it succeeds best on a deep loam soil, not too sandy nor too clayey. The preparation of the seed-bed should be as thorough as possible as success or failure of the crop often depends on this factor. Deep ploughing, so a.s to provide a deep feeding zone to the roots, is very essential. If the crop is to be planted in spring, winter ploughing wall prove very beneficial. Manuring, especially on soils of poor fertility will prove profitable. About 10 tons of well-rotted kraal manure, ploughed under during the winter months, to- gether with a dressing of 200 lbs. of superphosphate, applied in the row at the time of planting, is advocated. Cultural jMethods. — In areas having winter rainfall, or where the crop is grown under irrigation, March and April are considered the best months for sowing ; but where the crop is grown on dry-lands in summer, the spring months ar*» looked upon as the most suitable. About 1 lb. to 1-| lbs. of seed are required to plant an acre. The seed is put in by hand or by means of a small seed-drill, such as the Planet Junior, to a depth not exceeding 1 inch. The rows are made 18 to 24 inches apart. The seedlings are thinned out to a distance of 9 to 12 inches; under favourable conditions and on good soils the spacing is generally a little closer. Cultivation should commence as soon as the plants appear in the rows, for if delayed weeds are likely to smother the slow-growing seedlings. Hand-hoeing is necessary between the plants in the rows. Three to four cultivations during the growing-season is generally sufficient. The number will, how- ever, depend upon the amount of weed growth. Harvesting. — Generally speaking, the crop is ready to be harvested when the lower leaves turn yellow^ If this opera- tion is delayed ehe roots tend to become too fibrous. Lifting is tion is delayed the roots tend to become too fibrous. Lifting is found in the use of a lieavy single-furrow plough, which should cut a furrow deep enough to unearth the roots. In order to prevent sap from exuding, the leaves should not be removed from the roots for a couple of days. After the crop is lifted it is washed, if necessary, and then, as " fresh roots," sent to the factory, or it is cut a.nd dried by the farmer himself. MINOR CROPS. 339 Yield. — Yields of 3 to 8 tons of fresh root can be expected per acre, provided the soil and climatic conditions are favour- able. " This will result in a gross return of from £15 to £45 per acre at prevailing prices, a nett profit to the farmer of £7 to £30."^ According to experiments conducted, the Magdeburg variety has so far proved most suitable for our conditions . Uses, — Chicory is used as a substitute for, and as an adulterant of, coffee. It is also employed in the manufacture of chutney and confectionery. In Holland and other European countries it is grown as a pasture plant, for which pui-poses it is excellent, being both palatable and hardy. REFERENCES: 1 Journal of thft Dept. of Agriculture, March and April, 1921. — " Field Crops." — Wilson and Warburton. ' JoHrnal of the Dept. of Agriculture, August, 1921. — " Chicory as a Farm Crop," by E. Parish and K. M. Johnson. CHAPTER XXI DRYLAND FARMING ' The term " dryland farming " refers really to water con- servation in farm practice, particularly in arid and semi-arid regions, where irrigation is impossible or not practicable. The term is a misnomer and unfortunate, but, because of its general acceptance, is still adhered to. The following is a rough classification of land according to the average annual rainfall : — Less than 10 inches — arid. 10 — 20 ,, — semi-arid. 20—30 ,, —sub-humid. More than 30 ,, — humid. This is a very general classification, because factors such as run-off, evaporation and percolation, are not taken into consideration. For example, 15 inches of rainfall will pro- vide moisture for much better crops in a part having an annual evaporation of 20 inches, than in a part having an evaporation of 70 inches. For a proper appreciation of the subject a brief descrip- tion of the forms of water found in soils is necessary. Hygroscopic Water. — This form of water is held in the soil by the forces of adsorption. It is not capable of moving from particle to particle, and can be completely expelled only by heating the soil to the temperature of boiling water. Soils previously dried, so as to deprive them of all their moisture, and then exposed to moist air, absorb water vapour from the atmosphere with great energy at first ; both the rapidity of absorption and the amount absorbed, when full time is given, 340 DRYLAND FARMING. 341 vary greatly with the nature of the soil. Broadly speaking, sandy soils absorb the smallest amount, while clayey soils, and those containing much humus or finely divided ferric hydrate, take up the largest amounts. The quantity absorbed is almost entirely a function of the total surface exposed, but in no case is it sufficient to make the soil visibly moist. The percentage of moisture representing the full condensation of water upon soil from saturated air, under given conditions of temperature, is known as the Hygroscopic Coefficient. The hygroscopicity of soils is important in plant growth, because soils of high lijgroscopic power can withdraw from the moist air enough moisture to be indirectly of material help in sustaining the life of vegetation during droughts, in that high moisture absorption prevents rapid and undue heating of the surface soil to the danger point, and thus may save crops that would be lost in soils of low hygroscopic power. Except, perhaps, in the case of some desert plants, hygroscopic mois- ture cannot maintain normal growth. Capillary Water. — This form of water is held in the soil by capillary forces, and exists in the form of surface films around the particles. It differs from hygroscopic moisture in that it evaporates at ordinary temperatures, is not condensed again on the soil particles, and may move from one particle to another. Normally, it not only serves as the vehicle of all plant food absorbed from the soil during the growth of the crops, but also sustains the enormous evaporation by which the plant maintains, during the heat of the day, a temperature suffi- ciently low to permit of the proper operation of the various growth processes. Working with fine glass tubes, it is found that the height to which water rises by capillarity is inversely proportional to the diameter of the tube. The rise of water by capillary action, or the " capillary pull," in soils is somewhat analogous to this, being greatest in the finest textured soils. Verj' fine texture, however, offers considerable resistance to the move- ment of water, so that the rate of movement is slower than where the texture is coarser. Speaking generally, therefore, the capillary pull is strong in clays and weak in sands, but the rate of water movement in sands is far more rapid than in clays. Granulation of clay will increase the rate of move- ment, and compacting sands will strengthen the capillary pull. 342 CHAPTER XXI The quantity of capillary water retained varies greatly according to the nature of the soil, and is also largely a func- tion of the total surface exposed. Thus sands retain the least and clays the most. Compacting the former and granulation of the latter increase the capillary capacity in both cases. Humus greatly increases the capillary capacity of all soils. Gravitational Water. — This is free water, removable by drainage. The presence of gravitational water causes a water-logged condition in soils, hence is objectionable if main- tained for any length of time. Immediately after rain all soils contain more or less gravitational water. In semi-arid and arid regions, however, the excess of water is rapidly dis- tributed in the lower soil layers, where it assumes the capil- lary form. The poor growth of plants in water-logged soils is chiefly due to improper aeration, which is dealt with more fully under the subject of drainage. The Wilting Coefficient. — This is used as a basis for comparison of the capacities of diiferent soils for supplying water to plants. The wilting coefficient of a soil is its total moisture content at the point where plants just wilt. Per- manent wilting occurs when the soil still contains a certain amount of capillary water, and is due to the fact that the remaining moisture is either unextractable by the plant, or not extractable at a sufficient rate to meet the demands of the plant. Wilting is soon followed by death of the plant, unless water is added to the soil. The moisture contained in the soil at the wilting point is for all practical purposes unavailable to the plant. The available moisture, therefore, is the amount present in excess of the wilting coefficient. The wilting coefficient varies greatly in different soils ; in sands it may be as low as 5 per cent., or even less, while in clays it may be as high as 30 per cent. In general, the finer the texture the higher the wilting coefficient. Under normal conditions, however, the wilting coefficient of a par- ticular soil is the same for all plants. It will be obvious that the content of available moisture is the only sound basis for comparing the efficiencies of dif- ferent soils in regard to moisture supply — a sand containing 10 per cent, of water may supply considerably more available moisture than a clay containing 30 per cent. The relation of the various soil constants, and the dif- ferent forms of moisture present, is made clear in the follow- ing diagram (adapted from Hosier and Gustafson). Z3 6 ^ o 8S DRYLAND FARMING. Perfectly dry soil. 343 Hygroscopic Coefficient. 'VViltiiifr Coefficient. O Optimum moisture content for ordinary crops. ■Maximum capillary capacity. Completely saturated soil. Water is lost to plants through the agencies of transpira- tion, evaporation, run-off, and percolation. (1) Transpiration Eatio or the Water Kequirements OF Plants. — During the elaboration of plant structures, while a comparatievly small and practically negligible quantity of water enters into its composition, very large quantities are transpired through the plant. The transpiration ratio is de- fined as the quantity of water in pounds required to produce one pound of dry matter, or the ratio of the total water trans- pired to the total weight of dry matter produced in the crops. This ratio is affected by many conditions, chief among which are the average humidity, the fertility of the soil, and the kind of crop grown. 344 CHAPTER XXI The variation of transpiration ratio according to the crop is shown by the following figures obtained at experimental stations in the Western States : — Lucerne- •• ... 1,068 Barley ... 540 Eye 762 Wheat ... ... 507 Rape ... 743 Maize ... 368 Potato ... 636 Sorghum ... 322 Oats 614 Millet ... 275 Expressed otherwise, one ton of dry lucerne transpired 1,068 tons, or from 9 to 10 inches of water; one ton of rye transpired about 7 inches, and so on, for the weight of one acre-inch of water is roughly 110 tons. The transpiration ratios given above are not likely to be the same in South Africa, because our evartoration is about 70 inches per annum, while at these stations in America it was considerably less. The relative order, however, would probably correspond. In practice, a study of the transpiration ratios of plants is important w^hen, for example, we realise that a crop of millet utilises about half the amount of water that is required by a barley crop of equal weight ; also, that kaffir corn re- quires considerably less water than maize, which, without taking into consideration its other drought-resistant qualities, such as dormancy, shows why sorghums can be grown under drier conditions than maize. The more humid the climate the smaller is the water requirement of plants generally. Thus, in North Dakota, with an annual evaporation of 30 inches, the transpiration ratio of lucerne w^as found to be 518, while in Texas, with an evaporation of 54 inches, the transpiration ratio was 1,006. This means that tw^ice the amount of lucerne could be grown with the same amount of water in North Dakota as in Texas. The fertility of the soil has a direct influence on the amount of water lost by transpiration. Hellriegel obtained the following results in pot-cultures : — Units of Ca (NOJ, Dry Transpiration applied. matter. ratio. 0 1,111 724 4 8,479 399 8 13,936 347 12 18,288 345 16 23,026 302 20 25.504 292 DRYLAND FARMING. 345 The amount of water required by tiie plants was lessened as the plant food deficiency was rectified. Montgomery, experimenting on Nebraska soils in 1911, obtained the following results with wheat : — Transportation ratio. Yielding Capacity. Manured. Unmaimred. Poor (15 bushels) 350 549 Medium (30 bushels) 341 479 Fertile (50 bushels) 346 392 The yield on the manured ground was nearly double that obtained on the unmanured soil. Pagnoul, in France, found the transpiration ratio on fescue grass on fertile soil to be 555 as against 1,190 on an infertile soil. Widstoe, in Utah, obtained the following results with wheat : — Transportation ratio. Soil. Not cultivated. Cultivated. Fertile sandy loam ... 603 252 Fertile clayey loam ... 595 528 Infertile clay 753 582 Cultivation increases the availability of plant food, and in so doing lessens the transpiration ratio. All these experiments indicate that the more fertile the soil the less is the water requirement of crops. They show indirectly the importance of ascertaining soil deficiencies in parts where moisture is limited, since deficiency of one of the essential plant foods will sometimes double the amount of water transpired. The economy in the use of moisture effected by the recti- fication of a soil deficiency may in practice be responsible for the difference between good crops and cror> failures. Weeds. — Briggs and Shantz obtained the following trans- piration ratios for the various weeds mentioned : — Amaranth (A. retrofiexus) ... Pursland (P. oleracea) Gum Weed (Grindelia squ