K.'ologlcal Sci iils LAWES AGRICULTURAL TRUST Rothamsted Experimental Station Harpenden REPORT 1921-22 with the Supplement to the *'Guide to the Experimental Plots" containing The Yields per Acre, etc. To he obtaitted only of the Secretary Price 2j6 (Foreign Postage extra) Telegrams Telephone Station Laboratory, Harpenden No. 21 Harpenden Harpenden (L. M. 6? S.) HARPENDEN Printed by D. J. Jeffery. Vaughan Road V / ' ^ "^ . 19 2 3 ^.'^TO'AG! LAWES AGRICULTURAL TRUST Rothamsted Experimental Station Harpenden REPORT 1921-22 with the Supplement to the "Guide to the Experimental Plots" containing The Yields per Acre, etc. To be obtained only of the Secretary Price 2\6 (Foreign Postage extra) Telegrams Telephone Station Laboratory, Harpenden No. 21 Harpenden Harpenden (L. M. & S.) HARPENDEN Printed by D. J. Jeffery. Vaughan Road 19 2 3 Contents Experimental Station Staff Books published from Rothamsted General Account of Rothamsted Report of Work done 1921, 1922 Soil Cultivation ... Soil Acidity The Feeding of the Plant Fertiliser Investigations ... Effect of Manures on Crop Composition and Qual Quantity of Fertiliser and Crop Yield Soil Population and Plant Food Control of Soil Population The Plant in Disease Apicultural Investigations The Associated Farms : Woburn Leadon Court Loan of Lantern Slides Co-operation with Schools Demonstration and Lecture Arrangement Summary of Papers published : L — Scientific Papers Crops and Plant Growth : Botanical Department Statistical Methods and Results : Statistical Department Soil Organisms : Chemical Department Algological Section Bacteriological Department Protozoological Department ... Environmental Factors: Chemical Department Physical Department ... Plant Pathology : Entomological Department ... Insecticides & Fungicides Department Mycological Department n. — Technical Papers: Crops and Crop Production Organic Manures: Activated Sludge ... Green Manures ... Town Refuse Artificial Fertilisers ... General Agricultural and other Papers Recent Books by the Rothamsted Staff The Experimental Plots: Rothamsted : Notes on Seasons ... Expenditure and Cash Returns Costs of Ploughing ... Tables of Results — The Classical Experiments Later Experiments Woburn : Dr. J. A. Voelcker's Report Outside Centres : Malting Barley Trustees and Members of Council liii-li Page 4-7 10, 11 11-13 ... 13, 14 14-16 ... 16-20 i Quality ... 20, 21 22 22 23 24 26 26 26 27 27 28 ... 29-51 Nos i-vi 29-32 vii-xvi 33-36 xvii, xviii 36 xviii 36 xiv-xix 35-37 xx-xxv 38, 39 xxvi, xxvii 40 xxviii-xxxiii 40-42 xxxiv-xlii 42-44 xliii-xliv, 1 44. 45, 48 xlv-lii 46-49 49,50 Iv 50 Ivi, Ivii 51 Iviii 52 lix-lxvi 52,53 Ixvii-lxxvii 53,54 F 54 55-58 77-89 90 104 61-76 104 105 Experimental Station Staff (On July 1st, 1923) Director: Sir E. John Russell, D.Sc, F.R.S. Assistant Director: B. A. Keen, D.Sc, F.Inst. P. INSTITUTE of PLANT NUTRITION and SOIL PROBLEMS The James Mason Bacteriological Laboratory — Head of Department ... H. G. Thornton, B.A. Assistant Bacteriologist ... P. H. H. Gray, M.A. Laboratory Attendant ... Annie Mackness. Botanical Laboratory— Head of Department Assistant Botanists Laboratory Assistant Laboratory Attendants Plant Physiology — Chemical Laboratory Head of Department Assistant Chemists Barley Investigations (In- stitute of Brewing Re- search Scheme) ... Winifred E. Brenchley, D.Sc. F.L.S. Katherine Warington, B.Sc. Doris Marx, B.Sc. (jRACE BaSSIL. Lizzie Kingham. Doris Minney. F. G. Gregory, D Se A. T. Legg. E. Dorothy Kay. H. J. Page, B.Sc, A.l.C. G. C. Sawyer. T. Eden, B.Sc. C. T. Gimingham, F.I.C. R. G. Warren, B.Sc M. S. du ToiT, B.Sc. (S. African Govt. Scholar). N. Gangulee, B.Sc (Prof. Agric. Univ. Calcutta). H. Lloyd Hind, B.Sc, F.I.C special Assistant ... Laboratory Steward Laboratory Assistants Laboratory Attendant E. Grey. \. Oggelsby. a. h. bowden G. Lawrence. F. Seabrook. Gladys Tebb. Laboratory for Fermentation Work Head of Department Assistant Chemist Laboratory Assistant E. H. Richards, B.Sc, F.LC. (Elveden Research Chemist) R. L. Amoore, F.LC. Winifred Bateson. Laboratory for Antiseptics, Head of Department Assistant Chemist Laboratory Attendant Physical Laboratory — Head of Department Assistant Physical Chemist Assistant Physicists Punjab Drainage Board Scholar ... Laboratory Assistant Laboratory Attendant Insecticides, etc. — F. Tattersfield, B.Sc, F.LC. W. A. Roach, B.Sc, A.R.C.S., A.LC. Lyla Ives. B. A. Keen, D.Sc, F.Inst. P. (Goldsmith's Company's Phy- sicist) E. M. Crowther, M.Sc, A.I.C. (Empire Cotton Corporation Soil Physicist) \V. B. Haines, B.Sc, F.Inst.P. J, R. H. CouTTS, B.Sc A. N. PuRi, M.Sc W. Game. Edith Cooper. Protozoological Laboratory — Head of Department ... D. Ward Cutler, M.A. Assistant Protozoologists... Lettice M. Crump, M.Sc. H. Sandon, M.A. Annie Dixon, M.Sc. Laboratory Assistant ... Mabel Dunkley. Statistical Laboratory Head of Department Assistant Statistician Computer (Honorary) Laboratory Assistant R. A. Fisher, M.A. Winifred Mackenzie, B.Sc. (Econ. W. D. Christmas. A. D. Dunkley. INSTITUTE of PLANT PATHOLOGY Entomological Laboratory— Head of Department ... A. D. Imms, M.A., D.Sc. Assistant Entomologists ... J. Davidson, D.Sc. H. M. Morris, M.Sc. J. G. H. Frew, M.Sc. D. M. T. Morland, B.A. A. M. Altson, F.E.S. Assistant ... ... ... Norah Mardall. Field Assistant ... ... A. C. Rolt. Mycological Laboratory Head of Department Assistant Mycologists Algologist ... Laboratory Attendants W. B. Brierley, D.Sc. J. Henderson Smith, M.B., Ch.B., B.A Mary D. Glynne, M.Sc. B. Muriel Bristol, D.Sc. Gladys Temple. Doris Tuffin. FARM and EXPERIMENTAL FIELDS Manager Guide Demonstrator Superintendent of Exper mental Fields Assistant Supervisor S. J. K. Eames. H. V. Garner, B.A., B.Sc B. Weston. E. Cole. Librarian LIBRARY ... Mary S. Asi.in, Secretary Director's Private Secretary Special Assistant ... Assistant to Secretary Junior Clerk SECRETARIAL STAFF W. Barnicot. Janie Campbell, B.A., B.Litt. Charlotte F. S, Johnson. Eleanor D. Harford. Beatrice Allard. Engineer and Caretaker ... VV. Pearce. THE ASSOCIATED FARMS WoBURN Experimental Farm. Hon. Local Director: J. A. Voelcker, M.A., Ph.D. Leadon Court. (The property of E. D. Simon, Esq.) Manager: J. C. Brown, F.S.I. Publications of the Rothamsted Experimental Station For Farmers **The Book of the Rothamsted Experiments," by Sir A. D. Hall, M.A. (Oxon), F.R.S., Third Edition revised by Sir E. J. Russell, D.Sc, F.R.S. John Murray, 50, Albermarle Street, London, W.l. (in preparation). "Manuring for Higher Crop Production," by E. J. Russell, 1917. The University Press, Cambridg-e. 5/6 "Weeds of Farmland," by Winifred E. Brenchley, D.Sc, F.L.S., 1920. Longmans, Green & Co., 39, Paternoster Row, London, E.C.4. 12/6 "Farm Soil and its Improvement," by E. J. Russell, 1923. Benn Bros., Ltd., 8, Bouverie Street, London, E.C.4. For Students and Agricultural Experts ' The Rothamsted Memoirs on Agricultural Science," Quarto Series, vols. 1-3 (1859-1883), 20/- each. Octavo, vols. 1-7 (1847-1898), 30/- each. Royal octavo, vol. 8 (1900- 1912), vols. 9 and 10 (1909-1920), 32/6 each. Obtainable from the Secretary, Rothamsted Experimental Station, Harpenden, Herts. '*The Rothamsted Monographs on Agricultural Science," edited by Sir E. J. Russell, D.Sc, F.R.S. Longmans, Green & Co., 39 Paternoster Row, London, E.C.4. "Soil Conditions and Plant Growth," by E. J. Russell, Fourth Edition, 1921. 16/- "The Micro-Organisms of the Soil," by E. J. Russell and Staff of the Rothamsted Experimental Station, 1923. 7/6 The following- Monographs are in preparation : — "Soil Physics," by B. A. Keen, D.Sc. "Soil Protozoa," by D. W. Cutler, M.A., and Lettice M. Crump, M.Sc "Soil Bacteria," by H. G. Thornton, B.A. "Soil Fungi and Alg^," by W. B. Brierley, D.Sc, and B. Muriel Bristol, D.Sc "Chemical Changes in the Son.," by H. J. Page, B.Sc "Inorganic Plant Poisons and Stimulants," by Winifred E. Brenchley, 1914. The University Press, Cambridge. 9/- "The Manuring of Grassland for Hay," by Winifred E. Brenchley, D.Sc. Longrnans, Green & Co., 39 Paternoster Row, London, E.C.4 (in the press). "A General Textbook of Entomology," by A. D. Imms, D.Sc. Methuen & Co., Essex Street, Strand, London, W.C.2 (in the press). The following- are obtainable from the Secretary, Rothamsted Experimental Station, Harpenden, Herts : — "Agricultural Investigations at Rothamsted, England, during a period of 50 years," by Sir Joseph Henry Gilbert, M.A., LL.D., F.R.S., etc., 1895. 3/6 "Six Lectures on the Investigations at Rothamsted Experimental Station," by Robert Warington, F.R.S., 1891. 2/- "GUIDE TO THE EXPERIMENTAL PlOTS, RoTHAMSTED EXPERI- MENTAL Station, Harpenden." 1913. John Murray, 50 Albermarle Street, W. 1/- " Plans and Data of the Experimental Plots." 1923. 6d. For use in Farm Institutes "A Student's Book on Soils and Manures," by E, J. Russell, 1919. The University Press, Cambridge. 8/- For use in Schools "Lessons on Soil," by E. J. Russell, 1912. The University Press, Cambridge. 3/- For General Readers "The Fertility of the Soil," by E. J. Russell, 1913. The University Press, Cambridge. 4/- " Personal Reminiscences of Rothamsted Experimental Station," 1872-1922, by E. Grey, Superintendent of the Experimental Fields. 5/-. Obtainable from the Secretary, Rothamsted Experimental Station, Harpenden, Herts. 10 INTRODUCTION The Rothamsted Experimental Station was founded in 1843 by the late Sir J. B. Lawes, with whom was associated Sir J. H. Gilbert for a period of nearly 60 years. Lawes died in 1900 and Gilbert in 1901 ; they were succeeded by Sir A. D. Hall from 1902 to 1912, when the present Director, Dr. E. J. Russell, was appointed. For many years the work was maintained entirely at the expense of Sir J. B. Lawes, at first by direct payment, and from 1889 onwards out of an income of £2,400, arising^ from the endow- ment fund of £100,000 g-iven by him to the Lawes Agricultural Trust. In 1904 the Society for extending the Rothamsted Experi- ments was instituted for the purpose of providing funds for expan- sion. In 1906 Mr. J. F. Mason built the Bacteriological Laboratory; in 1907 the Goldsmiths' Company generously pro- vided a further endowment of £10,000, the income of which is to be devoted to the investigation of the soil, thus raising the total income of the Station to £2,800. In 1911 the Development Commissioners made their first grant to the Station. Since then Government grants have been made annually, and for the year 1922-23 the Ministry of Agriculture have made a grant of £22,030 for the work of the Station. Viscount Elveden, M.P., has generously borne the cost of a chemist for studying farmyard manure since 1913, and until his death the late Mr. W. B. Randall defrayed the salary of a biologist. The Sulphate of Ammonia Federation and the Fertiliser Manufacturers' Association jointly defray the cost of a Guide Demonstrator for the field plots. The laboratories have been entirely rebuilt. The main block was opened in 1919, and is devoted to the study of soil and plant nutrition problems ; a new block is being erected for plant pathology. The library has been much expanded and now contains some 20,000 volumes dealing with agriculture and cognate subjects. The equipment of the farm has also been expanded. The most important development of recent years has been the reorganisation of the work of the Station so as to bring it into touch with modern conditions of agriculture on the one side and of science on the other. The general organisation of the laboratory is now completed ; it is hoped to reorganise in the near future the farm and field work and to improve the field technique. The general method of investigation at Rothamsted is to start from the farm and work to the laboratory, or vice versa. There are four great divisions in the laboratory — biological, chemical, physical and statistical — which may be regarded as the pillars on which the whole structure rests. But the method of investigation differs from that of an ordinary scientific laboratory where the problem is usually narrowed down so closely that only one factor is concerned. On the farm such narrowing is impossible ; many factors may operate and elimination results in conditions so artificial as to render the enquiry meaningless. In place, therefore, of the ordinary single factor method of the 11 scientific laboratory, liberal use is made of statistical methods which allow the investig-ation of cases where several factors vary simultaneously. Thus in the crop investigations a larg-e number of field observations are made ; these are then treated statistically to ascertain the varying- degrees to which they are related to other factors — such as rainfall, temperature, etc. — and to indicate the probable nature of the relationships. Thus the complex problem becomes reduced to a number of simpler ones susceptible of laboratory investigation. It has been found desirable to widen the scope of the work by repeating- some of the more important experiments elsewhere, and some twenty centres in different parts of the country have been selected for this purpose. In October, 1921, the Station undertook, so long as its funds should allow, to carry on the continuous wheat and barley experi- ments at the Woburn Experimental Farm, till then conducted by the Royal Agricultural Society, and Dr. Voelcker gives his services as Honorary Local Director. In December, 1922, E. D. Simon, Esq., generously placed his Leadon Court farm at the disposal of the Station for experimental purposes. This is being used as a large scale test of the soiling system for keeping dairy cows (see p. 26) . REPORT FOR THE YEARS 1921-22 In order to appreciate properly the Rothamsted experiments, it is necessary to understand the purpose for which they are carried out. This purpose is to discover the principles underlying the great facts of agriculture and to put the knowledge thus gained into a form in which it can be used by teachers, experts and farmers for the upraising of country life and the improvement of the standard of farming. The most fundamental part of agriculture is the production of crops, and to this most of the Rothamsted work is devoted. On the technical side the problems fall into three groups, concerned respectively with the cultivation of the soil, the feeding of the crops, and the maintenance of healthy conditions of plant growth. The subjects will be taken in this order. THE CULTIVATION OF THE SOIL. Cultivation has been reduced to a fine art, and a good farmer independent of financial considerations could obtain very satisfac- tory results without consulting- the scientific worker. In practice, however, costs dominate the situation, and efforts are continuously being made to cut them down. Scientific investigation of all cultivation processes therefore becomes necessary. This is done in the Physical Department under Dr. Keen ; the effects produced 12 by the cultivation processes are investig-ated, especially those con- cerned with tilth, water supply and resistance to the passage of implements ; and the actual working- of typical implements is studied by means of dynamometer tests so as to see what power is required to do a given piece of work and how this is affected by the design of the implement. The first of these enquiries is needed to find out exactly what work has to be done and, if possible, to state the result in engineering terms ; the second shows how far our present types of implements are efficient, and if they are not, where the wastage of power occurs. It is fully recognised that the nature of the soil larg-ely deter- mines the amount of power required to do certain cultivation work. The measurements are showing that the farmer can alter his own soil so as to reduce the power requirement. Thus, on our heavy soil at Rothamsted the drawbar pull on a plough turning three furrows is of the order of 1,500 lb. and the "power factor" {i.e., drawbar pull in lb. multiplied by time in seconds taken to ploug-h 1 ft. length of furrow) is of the order of 550. But when the land is chalked there is a saving of power, which may vary from almost nothing up to 15%, according to the condition of the soil. The following are some of the data : — Drawbar pull in lb. Percentage Reduc- Field and Date Uncbalked Chalked Reduction due to Chalking tion in power factor due to Chalking Sawpit. Stubbles : Autumn ; dry . Cross ploughing weathered furrows Spring . Great Knott. Oct. January : very wet 473 521 924 1258 476 461 802 1181 Difference not significant 60 122 77 Nil 11.5 14.7 4.6 When the land is very dry or very wet, the chalking shows its effects least, but in moist conditions it acts strikingly. Farmyard manure and coarse ashes also reduce the power re- quirement in ploughing. On Hoos field the reduction has been, as compared with unmanured soil : — Due to Farmyard Mamire Coarse Ashes 22.6% 12.3% (values for unmanured soil: drawbar pull = 1,472 lb. ; power factor = 614.) Even artificial manures have some action. This has been studied in the first instance on the Hroadbalk wheat field where, however, the effects are much intensified from the circumstance that the same manures are applied year after year. The reduction in power requirement brought about by the use of artificial manures has been : — 13 FULL MINERALS, AND, IN ADDITION:— No Nitrogen Plot 5 Sulph/ammonia 2001b. per acre Plot 6 Sulph/ammonia 4001b. per acre Plot 7 Sulph/ammonia 6001 b. per acre Plot 8 Nitrate/soda 2751b. per acr^ Plot 9 14.2% 12.7% 16.3% 21.5% 8.1% when compared with the unmanured plot. The mineral manures have caused some reduction in power requirement, and a still further reduction has been caused by addition of sulphate of ammonia, but nitrate of soda has acted the other way and increased the power requirement. There are, however, other ways of altering- the resistance of soil to the plough, and an interesting electrical method is being studied. The depth of ploughing influences the power consumption more than might have been expected. An increase of only one inch in depth, i.e., going from 5" to 6" deep, increased the power consumption no less than 32%, a portion of which is due to the resistance offered by the "plough-sole" produced below 5" depth. Against this, maladjustments of the hitch were not particularly wasteful of power, although they caused bad ploughing. Perhaps the most surprising result was that the drawbar pull was practi- cally the same whatever the speed of ploughing within the ordinary limits of the tractor ; hence the power consumption per acre depends mainly on the speed and is smallest at the highest speeds. Another way of stating this fact is that the paraffin con- sumption per hour for the same tractor is approximately the same whether it is taking 1| hours or 3 hours to plough an acre of ground. The factors determining the resistance and the power con- sumption are intimately bound up with the physical properties of the soil which are systematically studied in the Physical Depart- ment. These physical properties determine also the water relationships — evaporation of water, percolation, etc. — which are being carefully investigated. This work has important applica- tions in tropical and sub-tropical countries where irrigation is practised, and the Indian Government regularly sends experts to study for a year or two in the Physics Department. Dr. Keen is also co-operating with Professor Sven Oden, of Stockholm, in elaborating the original Oden apparatus for estimating the amount of fine material of different sizes in soils. SOIL ACIDITY. The electrometric method used in the Physics Department by Mr. E. M. Crowther is giving good results and is sharply distin- guishing soils of varying degrees of acidity. The values are 14 labelled pH, and the lower they are the greater the degree of acidity. Thus the following Garforth soils have been tested : — pH value Very acid, wheat bad ..... 4.37 Less acid, wheat poor ..... 4.44 Still less acid, wheat better . . . .4.65 Still less acid, wheat good .... 4.82 Another set gave these results : — Acid, finger and toe prevalent on turnips . 5.64 Less acid, no finger and toe . . . .6.13 It is also shown that there is a closer relationship between the pH values and the Hutchinson-McLennan "Lime requirement" values than might have been expected, and the latter afford useful guidance in placing similar soils in order of acidity. THE FEEDING OF THE PLANT. Farmers are now thoroughly familiar with the fact that the production of heavy crops necessitates a skilful and adequate use of fertilisers. In spite of the severe agricultural depression of the past two years, there has been a considerable consumption of fertilisers : in some cases greater than in pre-war times ; this is shown in the foUow^ing table : — AVAILABLE SUPPLIES OF FERTILISERS IN TONS: GREAT BRITAIN AND IRELAND. (1) (1) Min. Ag. Statistics, 1921, Vol. LVI, p. 107 and private communication. No information is available as to actual consumption on farms or as to stocks carried over from one year to another. 1912 1918 1919 1920 1921 1922 Sulphate of Ammonia 60.000 250,000 240,000 240.000 112,000 147,000 Nitrate of Soda 100.000 9,000 40.000 100,000* 55,000* 33,000* Superphosphate 700,000 650,000 580,000 660,000 450.000 515,000 Basic Slag . . 300,000 550,000 485,000 550,000 210,000 283,000+ Potash Salts (in- cluding Muriate and Sulphate of Potash) . . . 80.000 5,000 50,000 125,000 53,000 201,000 Net imports for all purposes. + Ignoring imports and exports. Artificial manures influence not only the amount but also the character of the plant growth, and very often the quality of the produce. So long as farmers were confined mainly to farmyard manure they could and did discover for themselves its effects on the crop. But there are now more than thirty manures available for the farmer, and an ingenious chemist could make up over 6,000 different recipes for the potato crop alone, to say nothing of the mixtures required for other crops on the farm ; and to add to the complexity of the matter no manure acts in quite the same way on two different farms, while even on the same farm the effect may vary considerably from season to season. Hence the need for experimental work to discover the general rules by which to guide farmers as to the most suitable of the possible mixtures. 15 Tlie experimental work falls under two headings : — 1. The influence of fertilisers on the yield of crops under different conditions of soil and climate ; 2. Their effect in altering- the composition or quality of the crop. The effect of fertilisers on crop yield is studied in three ways. The most direct and accurate is the method of water cultures and pot cultures used in the Botanical Department. Here the condi- tions are so rigidly controlled that the factors, except the one under investigation, are kept as nearly constant as possible. The results are plotted on curves which, if they pass certain statistical tests, can be used as a basis for physiological deductions. Ex- periments of this kind have shown that the plant responds to two kinds of added substances : the usual nitrogen, phosphorus and potassium compounds required in rather large amounts ; and certain substances not yet fully known, which are required in very small amounts only. Agricultural chemists and farmers are familiar with the use of the former, but not of the latter. Dr. Winifred Brenchley has already studied certain cases, notably manganese, and this year Miss Warington showed that broad beans and certain other leguminous plants die prematurely unless they receive a small quantity of boric acid in addition to the so-called ''complete" plant food. The results suggest that some of the anomalies and unexpected failures in fertiliser experience may be traceable to the absence of some of these substances required in homeopathic doses only. But we must caution farmers that this work is still a long way from practical application and they must on no account be beguiled into buying "catalytic" or "radio- active" fertilisers in the hope of getting something outside the usual fertiliser constituents. We have tested several of these supposed "radioactive" fertilisers, but failed to obtain any benefit from them. This method of experiment is invaluable where the factors can be controlled, but otherwise it breaks down. For this reason it does not give entirely reliable guidance for field practice where the weather conditions are entirely uncontrollable, and it completely fails to show how weather conditions influence the efliciency of the various fertilisers. A second method is therefore adopted. The Rothamsted data, extending as they do over a long series of years, can be subjected to modern methods of mathematical analysis. The variation in crop yield from season to season is traced to two types of causes : (a) annual, the variation in each season being independent of the years before and after, e.g., weather; (h) continuous acting, of which there are two forms, steady, such as soil-deterioration, and variable, such as weed infestation. Mr. Fisher has devised methods for finding out how much of the variation is due to each of these causes, and has been able to trace out the average effect of rain above or below the average in amount in each month of the plant's life. Methods are being developed to find out how much the crop yield is likely to be altered by deviations from the average weather and other conditions, and important results may emerge. There must always be a risk about crop yields whatever steps the farmer may take. At present the risks are entirely speculative. 16 It is hoped as a result of this work that they may become calculable and therefore insurable, just as is the risk of death. We want to be able to say to farmers, "If your soil and weather conditions are of a certain kind, the chances are so many to one that a specified fertiliser mixture will give an increased crop of so many tons or bushels per acre." The difficulties of the work are very great, but they are being steadily overcome. Meanwhile, however, the farmer urgently needs precise in- formation about fertilisers, and it becomes necessary to adopt a third method which, though not as accurate as the single factor or the statistical methods already described, nevertheless gives some of the information desired. This consists in repeating a field experiment as exactly as possible at a number of centres carefully chosen to represent important soil and climatic conditions. For example, a Wold farmer sees our experiments, and asks if he could get the same results on his own farm. At present we cannot say, because we do not know the effect of differences in soil type and climatic conditions ; but this can be ascertained by repeating one of our typical experiments on a typical Wold farm and then comparing the results with our own. This is being done on some 20 carefully selected farms in different parts of the country. FERTILISER INVESTIGATIONS. In addition to field and pot tests these necessitate a consider- able amount of chemical work, which is carried out in the Chemical Department under Mr. Page. thp: new nitrogenous manures.— urea. Our experiments indicate that this substance has a value between that of nitrate of soda and sulphate of ammonia. In addition it has two attractive features — it is highly concentrated and it exerts no harmful influence on the soil (p. 93, p. 101). AMMONIUM CHLORIDE. Experiments made in the past two seasons at Rothamsted and the outside centres show that the yields from ammonium chloride, when those from ammonium sulphate containing an equal amount of nitrogen are put at 100, are : — Cereals . Potatoes . Mangolds 1921 Rothamsted 104 112 95 Average of all outside centres 117 91 112 85 95 1922 Rothamsted 103 not Average of all outside centres 99 98 98 Two groups of results in each case. t With dung. The value without dung was ?9. 17 Examined in detail the results appear to fall into two groups. In both years the larger number of the values fall between 90 and 100, but a second group of values falls distinctly above 100. The indications are that ammonium chloride would generally be about 5 to 10% less effective than ammonium sulphate containing the same amount of nitrogen, but in some circumstances, which we cannot yet define, it may be somewhat more effective. THE NKW BASIC SLAGS AND MINERAL PHOSPHATES. The object of these experiments is to compare the respective fertiliser values of the old Bessemer slags, the more modern open- hearth slags, some of which are of high and some of low solubility in the official citric acid solution, and the mineral phosphates. The general result up to the present is that the high soluble slags are quicker in action and more effective than those of low solubility, but the low soluble slags are more effective than their solubility indicates. These effects are seen in their simplest form in pot experiments where all conditions of growth are carefully controlled. In the field, however, the effects may be masked by various factors, such as water supply, temperature, etc. A comparison made in 1922 gave the following results : — Pot Expeui- MENTS 1 Field Experiments All crops 1922 Turnips Barley ; Tons per { acre Tcr cent. Bushels per acri; Per cent. Open hearth slags 90% soluble , 30% soluble . Mineral phos- phates : Gafsa Nauru Control 114 106 109 101 100 1 24.3 23.3 23.2 22.3 22.5 108 104 103 99 100 27 29 27.6 34 80 85 81 100 The turnip results in the field fall into line with those of the pot experiments, although the differences are probably within the experimental error, but the barley results fall out altogether. Inspection of the growing crops, however, showed that up to the end of June the appearance of the barley plants accorded with the pot experiments, but all this was lost before harvest. In the grass experiments two distinct cases arise : — 1. If the herbage is poor, and the growth poor, the slags may increase the yield of hay ; If the grass is better and gives larger crops of hay, the slags may not increase the yield, though they may in- crease the amount of clover and thus improve the quality, is seen on inspection or on botanical analysis, or, better still, by a grazing test. The following results were obtained in the last two seasons : — 2. This 18 1 POOR GRASS LAND: 11 CWT. HAY ONLY PER ACRE. 1922 Cwt. per Acre. Control . 10.9 Open hearth slag, 90% soluble . . . 16.5 ,, 30% soluble . . . 18.7 Gafsa phosphate ...... 18.8 IL BETTER GRASS LAND: 1-U TONS HAY PER ACRE.* Yield of Hay cwt. per acre Live weight increase i Sheep, lb. per acre 1921 1922 1921 1922 Bessemer slag . 24.3 17.3 59 143 Open hearth, high^ sol ' 23.9 16.6 43.3 j 112 Control 59 ! 116 1 Open hearth, low sol. 26.5 21.1 67.3 1 \ 123 Gafsa .... 25.4 22.5 88 , 107 Control 26.4 20.1 90 1 115 * The slags used on the grazing land were not identical with those used on the hay land, but they were of similar types. Inspection shows that the amount of clover is highest on Bessemer slag plots. There is less on the high soluble open hearth slag, still less on the low soluble slag and Gafsa plots, and least of all on the unmanured. The effects are beginning to show in the live weight increases. THE POTASSIC FERTILISERS. A beginning has been made with a test of the new potassic fertilisers, especially on the potato crop. In 1921 the crop yields were very poor, owing to the drought; the advantage of potash showed, however, in keeping the plants alive some time after those on the "no potash" plots had died. In 1922 the yields were much better ; the chloride gave practically the same yield as the sulphate. When, however, salt was present in addition to the chloride there was a drop in yield, especially where no dung was supplied. Taking the yields with potassium sulphate as the standard, the results were, for the potato crop : — KOTII/ MSTED Other t ENTKES Dung No Dung Dung No Dung Potassium sulphate . 100 100 100 100 Potassium chloride alone 98 106 99 104 Pot/chlor. plus salt : pure . . . . 100 96 — Pot/mnnure salts (20% K,0) . . 94 — Sylvinite 93 82 Kainit .... 92 88 The experiments are being continued. 19 MAGNESIUM SALTS AS FERTILISERS. I^'ield experiments made in 1922 with magnesium sulphate in- dicate that while apparently ineffective in ordinary conditions (apart from the potash-starved plots at Rothamsted) , it has, in certain farming conditions, a considerable fertilising value : — EFFECT OF MAGNESIUM SULPHATE ON THE YIELD OF POTATOES RECEIVING POTASSIUM SULPHATE. ROTHAM.STED Akmstuoni; Coli.ec;e Ckntres . Blavdon Wai.bottle Complete manure and — No magnesium sulphate Magnesium sul- phate (a) (b) . 100 102 97 Dung 100 114 No Dung 100 108 Dung 100 129 No Dung 100 118 (a) Sulplialf of potash used in complete manure. (b) Muriate of potash used in complete manure. We cannot at present explain this result, but the experiment is being repeated. ARTIFICIAL FARMYARD MANURE. This material is now being made at a number of centres and on a large .scale. Some 2,000 tons of straw, in lots varying up to 80 tons in quantity, have now been treated under the direction of Messrs. E. H. Richards and R. L. Amoore on different farms in the country — mostly in the Eastern Counties. The material has been considerably improved by the introduction of phosphates, but there remain difficulties connected with the wetting of the straw. The product is not yet up to a good sample of true farmyard manure, but it is being steadily improved, and the 1922 results are distinctly promising. The following is a large scale test made by the Chelmsford Institute with potatoes on an Essex farm :-^ No Manure Artificia only s Artificials plus Cow Manure .Artificials plus Straw Manure Ware . Seed Chats Tons Cwts. 3 11 18 6 0.. 0 1 Tons (~\\ts. 7 14 17 4 2 3 Tons Cwts. Ors. 10 13 '0 15 1 8 3 Tons Cwts. Ors. 9 5 '3 18 0 7 1 Total 4 15 1 8 16 1 11 17 0 10 11 0 It is also shown that this artificial farmyard manure does not lose nitrogen on exposure to weather, while heaps of natural farm.- yard manure under similar conditions lost as much as 10% to 30%. The development of practical applications of this kind involves an immense amount of detailed work and a business organisation differing entirely from that of an experimental station. Artificial 20 farmyard manure has therefore been handed over to a non-profit- making- syndicate — the Agricultural Development Company (Pyrford) Ltd., the Chairman of which is Viscount Elveden, M.P., and under these auspices the work is prog^ressing- favourably. The results indicate that this is the be.^t method of bringing a new discovery into practical use. The nature of the gas given off in the fermentation of straw and Nile Sudd (papyrus stems) was studied in the Chemical Department at the request of the Air Ministry. So long as air was present, the gas obtained was carbon dioxide, but when the air supply was cut off methane and hydrogen were obtained in addition. The relative proportions of these two gases depended on the reaction of the medium ; if it was kept neutral by means of calcium carbonate there was a considerable quantity of methane along with a certain amount of higher hydrocarbons ; if it became acid the total evolution of gas was much diminished and the methane largely disappeared, hydrogen being the chief constituent. The maximum production of methane was obtained at a temperature of 35^-40° C. and in presence of some nitrogen com- pound to serve as nutrient to the organisms. In these conditions a yield of 4,400 cubic ft. of gas was obtained per ton of wheat straw, and 9,400 cubic ft. per ton of Nile Sudd ; of this gas 38% was carbon dioxide and 62% combustible gas made up of 56 parts of methane and 6 of hydrogen. The maximum production of hydrogen was obtained when the medium was allowed to become acid, but the total yield of gas was then only l/30th that given under neutral conditions. EFFECTS OF MANURES ON THE COMPOSITION AND QUALITY OF CROPS. Fertilisers affect the habit of growth and the quality of the crop, but the changes, though recognisable by the practical expert, are often so subtle that the chemist is as yet unable to characterise them or to connect them up in any definite way with the chemical composition. In the Rothamsted experiments the practical expert is asked to grade the produce, and his reports are used by the chemist in seeking to trace the chemical relationships. Malting barley and potatoes are being studied in some detail. MALTING BARLEY. The experiments are carried out at 13 different centres as part of the Research Scheme of the Institute of Brewing, and full details are given in their Journal. The same seed and the same manurial treatment are adopted at each centre. The yields are given on p. 104. The samples of grain are valued by a committee of expert buyers and are analysed by an experienced brewers' chemist ; certain typical samples are separately malted by a maltster. The results will show how quality is affected by manurial treatment, soil and season ; in addition, it is hoped from the data thus obtained to deduce chemical relationships which will enable us to express better than at present the value or quality of barley in chemical terms. The experiment began in 1922, one of 21 the worst seasons in the last 30 years for quality of barley. When the barleys from the different farms are compared, their values are related to nitrogen content ; when, however, barleys from different manurial plots on the same farm are compared, the relationship is less marked ; it can be shown statistically that the effect is reduced at least one-half (p. 50) . POTATOES. The relative effects of sulphate of potash, muriate of potash and salt have been studied. The samples were valued by an expert buyer — George Major, Esq., of Major Bros., King's Cross Potato Market. There was no obvious connection between manuring and valuation. Cooking tests, however, showed certain relationships. The professional cooking test was kindly carried out by Messrs. Lyons, the well-known caterers, who placed the potatoes in the following order : — MESSRS. LYONS' COOKING TEST: ORDER OF (JLIALITY. L Sulphate of potash. 2. Muriate of potash. 3. Muriate of potash and salt. No potash. No farmyard mniuirc was used with tliis sit. A home c(K)king test gave the following result : — 1. Sulphate of potash. 2. Muriate of potash and salt. 3. No potash. 4. Muriate of potash. No dung was given to this sot. On the dunged plots th(> differences were smaller. It will be observed that both agree in placing the sulphate- treated potatoes at the head of the list, and of the others the only fertiliser as to which there is disagreement is the chloride. Certain differences were detectable in the laboratory. l^he tubers receiving sulphate of potash had a higher specific gravity and a larger percentage of dry matter than any others, excepting only those from the no-potash plots receiving dung. The quantities of starch are being determined. WHEAT. The wheats grown at one centre — Seale Hayne, Devon— and receiving respectively sulphate of ammonia, muriate of ammonia and no nitrogen, were examined by Dr. Humphries. The two samples grown on muriate of ammonia contained slightly more gluten than those grown on sulphate, but no difference could be detected by the expert buyer or the miller. The baker in one case put the ammonium chloride plot above, and in the other below, the ammonium sulphate plot, but he preferred the unmanured wheat. 22 THE RELATION BETWEEN QUANTITY OF FERTILISER AND CROP YIELD. These investigations started from the Broadbalk result that the second increment of nitrogenous fertiliser produced a larger incre- ment of yield than the first. If this proved generally true in farm practice it would mean that under normal conditions of price a farmer would be well-advised to manure pretty liberally. The Broadbalk experiment has, however, certain unpractical features, and a series of field trials under ordinary farm conditions has been carried out. The results with wheat in 1920 favoured this view (Report 1918-20, p. 79), the yields without nitrogen being 28.9 bushels and with the higher dressing 35.9 bushels per acre. Unfortunately both in 1921 and 1922 the wheat crops were very poor, the yields without nitrogen averaging 17.5 and 13.4 bushels per acre respec- tively, which values were hardly raised in 1921, and only to 17.1 and 19.7 bushels by the single and double dressing respectively in 1922 (p. 93) . No definite conclusion can be drawn from these figures. Potatoes made much better growth. The tops were not weighed, but the tubers increased in yield with successive incre- ments of sulphate of ammonia, and gave a record crop for this land. The increases for the second increment, however, were not greater than for the first, but probably slightly less ; nevertheless under ordinary conditions of price the results would have been very profitable. The figures were : — GREAT HARPENDEN FIELD: POTATOES, (Mean of duplicate set.) 1922. Tons per acre 1 realniciit Dung (15 tons) No Dung Basal manure only : no nitrogen 6.07 5.50 )) M plus 11 cwt. sul- phate/ammonia 7.99 7.37 »» >> plus 3 cwt. sul- phate/ammonia 9.73 8.97 >» ■>} plus 4^'i)cwt. sul- phate/ammonia 10.08 8.98 Uasal manure (with duni<) equals 4 cwt. super, 1'/^ cwt. sulphate/potash. Masai manure (no dung) equals 6 cwt. super, 2 cwt. sulphatc/potasli. (1) Of this A'/a cwt., 3 were applied with the seed, and I'/g given later as top dressing. These apparent discrepancies are being fully gone into during ihe coming season. THE SOIL POPULATION AND THE PRODUCTION OF PLANT FOOD IN THE SOIL. The important investigations by Mr. Cutler and the staff of the I'rotozoological Department have necessitated considerable revi- sion of our ideas of the soil population. It had always been supposed that the numbers of organisms present in natural soil 23 were fairly constant so long- as the conditions of temperature, water supply, etc., remained the same. Mr. Cutler's work showed that this is not the case ; the protozoa and bacteria vary in numbers from day to day (p. 38) , while Mr. Thornton has shown that the bacteria may vary from hour to hour. Careful experi- ments are beings made to see if the production of plant food by the organisms varies in the same way. The changes in numbers of bacteria seem to be brought about by changes in numbers of active amoebte, but it is not clear why the amoebae should fluctuate as they do. It does not appear that their variations in numbers are determined primarily by variations in rrioisture supply or temperature ; there seems to be some deep seated biological cause at work. Besides these hour to hour and day to day variations, there seems to be a seasonal variation in numbers ; bacteria, protozoa and, apparently, fungi and algae, are uplifted in number in Spring and Autumn, but depressed during Summer and Winter. Laboratory experiments have been begun to find an explanation, but the problem is clearly very complex. The depressing effect of protozoa on bacteria in the soil was directly demonstrated by inoculating protozoa and bacteria into sterilised soil ; the numbers of the latter were greatly reduced (p. 38). This experiment has often been attempted before, but without success, the experimental difficulties having proved too great. The Bacteriological Depart- ment, under Mr. H, G. Thornton, has successfully worked out methods by which the bacteria in the soil can be counted, and their changes in number followed, to a degree of refinement and accuracy that satisfies statistical tests of far greater stringency than had been previously applied (p. 37). THE CONTROL OF THE SOIL POPULATION. This, work was seriously checked in March, 1921, by the death of Mr. W. B. Randall, who had provided funds for the main- tenance of a special assistant. It is, however, being slowly continued. The disappointing results given by certain organic agents which promised well have been traced to their decomposition in the soil. This is in the main bacterial, and a special study has been made by Messrs. Thornton and Gray of the bacteria which break down phenol, cresol and naphthalene. The introduction of certain groups into the molecule retards decomposition and intensi- fies activity ; thus nursery experiments indicate that dichlorcresol is some 25 times as potent for sterilising purposes as ordinary commercial cresol. The large scale experiments are recorded in the report of the Cheshunt Experimental Station. The effect on the micro-organisms of treating soil with phenol is being studied in the Bacteriological and Protozoological De- partments. Three groups of bacteria are found capable of decomposing this substance, belonging respectively to the Mycobacterium, Pseudomonas and Clostridium types; the Myco- bacteria are interesting among soil bacteria in that they appear to have a definitely discontinuous geographical distribution ; the Pseudomonas organisms are apparently of chief importance in phenol decomposition, as they greatly increase in numbers 24 when phenol is added to the soil. But there is also an unexpected chemical decomposition which has been studied in the Chemical Department by Mr. Sen Gupta, under Mr. Pag-e ; it appears that the small quantity of manganese oxide in the soil plays an im- portant part here. Serious efforts are also being made to control wart disease of potatoes. Sterilising- agents have been found capable of destroy- ing the organisms in a badly infested plot of land so that perfectly clean tubers could be grown ; the various problems arising out of the practical application of the method are being- studied by Dr. W. B. Brierley, Mr. VV. A. Roach and Miss Cilynne en plots of land at Ormskirk and at Hatfield. THE PLANT IN DISEASE. (ENTOMOLOGICAL, MYCOLOGICAL, INSECTICIDE AND FUNGICIDE DEPARTMENTS.) Much damage to crops is caused by the attacks of insects and fungi. These pests can often be kept in check by spraying, but on the farm it would usually be cheaper, where possible, to enable the plant itself to resist the attacks. Both methods are being studied. In the case of one disease — the Wart Disease of Potatoes — certain varieties are absolutely immune. Attempts are being made to find out the reason for this. Immunity might be due to some- thing made in the leaf and distributed throughout the plant, or, on the other hand, it might result from some special characteristic of the lower part of the plant. In order to test these possibilities, Mr. Roach is building up new varieties of potatoes by grafting one sort on to another ; he has grafted immunes on to susceptibles and vice versa ; the resulting plants are then grown in infested soil. So far the substitution of a top from a susceptible plant on to an immune variety has caused no loss of immunity, nor has the substi- tution of the top from an immune to a susceptible variety conferred immunity. It does not appear, therefore, that immunity is the result of any action in the leaf. Considerable attention has been paid by Dr. Davidson to the aphids attacking broad beans. It is shown that the rate of multiplication of the insect on the plant differs for the different varieties of bean, though unfortunately the most resistant of the beans has little commercial value. Attempts are therefore being made to breed a variety of high resistance and at the same time having a value to the farmer comparable with that of the present kinds. Even with the same variety, however, the power of resistance is affected by the dissolved substances in the plant tissues, and this can be modified by changes in the nutrients supplied to the plant. In both directions there seem to be possi- bilities of the control of this troublesome pest. The usual history of this particular pest is that the asexual forms (which do the damage to the crop) continue throughout the Summer, and are then followed by sexual forms in October which produce eggs that lie dormant through the Winter and hatch out in the following April. Dr. Davidson has, however, shown 25 that the asexual forms can continue living- on beans in a green- house through the Winter and flourish vigorously during the following Summer, thus forming a further source of infestation. This is of importance in certain branches of the glass-house industry. Mr. J. G. H. Frew has made a study of the biology of the gout fly, and it appears ix)ssible that the severity of the attack can be diminished by appropriate manuring. The relation of the time of sowing to the probability of attack is being studied. Another method of control under investigation in the Entomo- logical Department is through the agency of the natural enemies of injurious insects. Parasites of certain pests — the earwig, pear slug larva, and pear leaf midge — are being bred by Mr. Altson for supply to the New Zealand Government. The discovery and suppression of winter or alternative hosts is connecting the entomological work with the weed investigations which have for some years been made by Dr. Brenchley in the Botanical Department. While one hopes for the fullest possible measure of success of these methods of controlling pests, it remains highly probable that control by spraying will always be of great importance. Serious efforts to improve this are therefore being made by Mr. Tattersfield, in conjunction with Dr. Imms and Mr. Morris. For insect pests the spray fluids may be of two kinds — contact poisons and stomach poisons. Of the latter, arsenic in one or other of its combinations is well known and is quite effective, but unfortunately it is poisonous to man and animals. Of the contact insecticides, nicotine is at present the best, but it is subject to the disadvantages of restricted source of supply and high price. Systematic attempts to find substitutes are steadily yielding results ; the method consists in finding the toxicity of an organic compound towards certain test organisms (bean aphis, the larvae of the common Lackey moth and of Selenia illiimaria) , then pre- paring derivatives to see which groups and positions tend to the greatest increase in toxicity. The experimental difficulties are great but it is believed that they are now overcome ; some of the new substances are sufficiently promising to justify study on the field scale. Considerable attention has been given by Messrs. Tattersfield and Roach to the extraction of toxic substances from tuba root {Derris elliptica), and as the percentage of toxic material in different consignments may vary between 7 and 22, a method of evaluation has been devised (p. 45) . Fungi are controlled by spraying just as insects are, but little is known of the processes involved. Dr. Henderson Smith finds that the number of spores of the fungus (Botrytis cinerea) killed by a solution of phenol of given strength, is for short exposures small ; for longer exposures it rapidly increases, but there is always a residue of spores that die very slowly. The results are expressible by a sigmoid curve. One practical result is that an experimenter can ascertain the strength of a fungicide which, in the steeping of seed, would cause the maximum injury to the fungus with the minimum injury to the grain. Heat acts much in the same way as phenol, with the distinction 26 that there is no delay in action such as is occasioned in the case of fungicides by the slow penetration of the chemical agent. APICULTURAL INVESTIGATIONS. The circumstance that Dr. Imms was interested in bees led the Ministry of Agriculture to suggest that the Entomological Department should undertake the study of bees as honey pro- ducers, leaving bee diseases to be studied at Aberdeen as at present. Mr. D. M. T. Morland was appointed to be in charge of the work, and he will at an early date proceed to the United States to study the methods in use there. In the meantime, two minor problems of practical importance are being investigated : the suit- ability of metal combs in place of those naturally built, and the situation of the frames in relation to the hive front. A field laboratory has been erected and is now in working order. THE ASSOCIATED FARMS. WOBURN. In 1921 the Royal Agricultural Society gave up the Woburn Experimental Farm which they had carried on continuously since 1870, and its two best known fields — Stackyard and Lansome — were in October, 1921, taken over by the Rothamsted Experi- mental Station so as to ensure the continuance of the permanent wheat and barley experiments which are second only to those of Broadbalk and Hoos fields in point of age. The necessary funds are obtained from a special grant of the Ministry of Agriculture. Dr. Voelcker continues to supervise the experiments as he has done since 1890 ; the continuity of the records is therefore assured. It should be recorded that he acts in an honorary capacity, freely giving much time and trouble to this work. His report will be found on p. 61. LEADON COURT. In December, 1922, E. D. Simon, Esq., then Lord Mayor of Manchester, offered us the use of his farm at Leadon Court, Ledbury, for experimental purposes, himself generously defraying the expenses incurred. It was decided to devote the whole farm to a test of the soiling system of keeping dairy cows, which has aroused much interest among farmers. Small scale trials at the Harper Adams Agricultural College had indicated the feasibility of all of the processes involved, but no conclusions as to the economic value of the system could be reached. Mr. J. C. Brown was appointed manager. The farm is 240 acres in extent, there being at present 110 acres of arable and 140 of grass, of which 20 acres will be ploughed out, making altogether 130 acres of arable and 110 of grass. It is expected to maintain a herd of 100 cows in full milk, and in addition some 30 dry cows, and some 30 young heifers coming on ; also a herd of pigs. It is also hoped to have a considerable amount of wheat for sale. 27 The scheme of cropping for 1923 is as follows : — Expe cted Yield creage Green Food tons per acre 10 Rye 10 16 Marrow-stem kale 20 8 Mangolds 30 12 Seeds in wheat and pea 10 10 Clover aftermath Dry Ration 5 12 Wheat and pea 3 10 Clover 3 18 Mixtures (beans, and barley) peas, wheat, H 26 Wheat The ration per cow will be, from mid-October to the end of May — 601b. green fodder and 151b. dry fodder (81b. mixtures and 71b. hay) . For the rest (June to mid-October) the cows will be at grass, aided by forage crops. On the best pasture the cows are being grazed in rotation, the aim being to secure the advantages of the continental practice of tethering without its disadvantages. They receive also one feed per day of chaffed rye and peas. LOANS OF LANTP:RN slides to LECTURERS. Lecturers on agricultural science can obtain from the Rotham- sted Experimental Station the loan of certain lantern slides free of charge, but on condition that all breakages are replaced. CO-OPERATION WITH SCHOOLS AND OTHER AGENCIES Three of the departments have found it advantageous to invite the co-operation of public and elementary schools for the collection of data, and it is satisfactory to record that the scheme has proved successful. In the first instance, a committee of the Science Masters' Association, under the chairmanship of O. H. Latter, Esq., M.A. (Charterhouse School), was formed, and a number of public schools co-operated. Relations have now been secured with practically every type of educational institution : public schools, secondary schools, training colleges, and rural schools. Certain observations on weeds carried out by training colleges and country school teachers are proving very useful to the Botanical Depart- ment; other observations of times of flowering, ripening, etc., are of assistance to the Statistical Department in estimating the effect of season on plant growth. 28 Recently, throug-h the assistance of the Ministry of Education, it has been possible to reach the rural school teachers, and lectures on ag-ricultural science have been g-iven at vacation courses by the Director and members of the staff. Certain problems in soil physics are best attacked by simple experimental studies of a number of soil types. During the un- precedented drought of 1921 several of the upper science forms of the public schools determined the moisture contents of specified field soils in their district, thus obtaining information required by the Physical Department for its investigations on the water relationships of soils. DEMONSTRATIONS AND LECTURES TO FARMERS AND STUDENTS. The appointment of Mr. H. V. Garner as Guide Demonstrator has made it possible for the Station widely to extend facilities for visiting the plots. Farmers and agricultural students are cordially invited to Rothamsted at any time convenient to themselves. May and June are good months for seeing the grass plots, July for the cereals, and September and October for the mangolds and potatoes. In the Winter, Mr. Garner is available for giving lectures on the Rothamsted results to Farmers' Clubs and similar organisations. 29 PUBLICATIONS DURING THE YEARS 1921-22. SCIENTIFIC PAPERS. CROPS AND PLANT GROWTH. I. Winifred E. Brenchley. ''Effect of Weight of Seed upon the Resulting Crop." Annals of Applied Biology, 1923. Vol. X. pp. 223-240. Experiments were carried out in water cultures with peas and barley, in which the competitive factors were eliminated as far as possible in order that the results could be more closely correlated with the initial weights of the seeds. The chief results are as follows : — 1. — There is a steady and considerable rise in the dry weight of the plants as the initial weight of the seed increases. This occurs with both a limited and an abundant food supply. 2. — The efficiency index (rate per cent, increase per day) falls gradually as the weight of the seed rises. With prolonged periods of growth this tends ultimately to counter-balance the initial advantage gained by plants from the heavier seeds, but with annual crops as cereals, roots, peas, etc., harvesting occurs before this equilibrium is reached, leaving the advantage with the heavier seeds. 3. — The relative development of shoot and root is to some extent influenced by the initial weight of the seed, but may vary with the species and with the amount of available food. 4. — The results lend support to the growing agricultural practice of advocating the use of large heavy seed, especially with annual crops. The advantage in the case of perennials would appear to be less, if any, but this has not been determined by laboratory experiments. II. Winifred E. Brenchley, assisted by Kharak Singh. "Effect of HigJi Root Temperature and Excessive Insolation upon Growth." Annals of Applied Biology, 1922. Vol. IX. pp. 197-209. When similar water culture experiments are repeated at different seasons of the year and under different environmental conditions, certain variations in result occur which appear to be associated with the temperature of the nutrient solution in which the roots are immersed. Under ordinary environmental conditions of temperature and sunlight the growth of peas, as of barley, is seriously hindered by overcrowding, even when each plant receives a similar supply of food and water. Not only is less dry weight produced, but the pods become thin and distorted, and fail to develop their seeds properly. Growth tends to be depressed in hot sunny weather when no protection is afforded. The chief detrimental factors concerned appear to be high temperatures at the roots, acting together with strong and prolonged sunshine, though the two factors acting in- dividually are much less harmful. Under these conditions, crowding shelters the roots from overheating and the leaves from too much sunlight, and up to a certain point crowded plants make better growth than those spaced well apart. Overcrowding, 30 however, still depresses g-rovvth, probably because the lig'ht and root temperature reductions are too great. Provided insolation is not excessive, the amount of daily fluctuation of root temperature over a total range of about 22^ C. (6.70 — 28.9° C.) has comparatively little influence upon growth; high maxima and low minima give similar results to low maxima and relatively high minima, pro\ ided the average mean tempera- tures are not too dissimilar. With high root temperature a difference in the degree of insolation or in the angle of incidence of the sun's rays may have a considerable influence on growth, a slight easing off of the solar conditions enabling much better growth to be made. With very strong sunshine, reduction of high maximum root temperatures (29° C. or above) allows of satisfactory growth when unprotected plants are rapidly killed. The inhibi- tory action of too high temperatures at the roots is thus clearly shown. Nevertheless, the growth so made is less good than under more normal conditions of insolation, thus demonstrating the harmful action of too powerful sunlight, when all the root temperatures rule high. Root temperatures appear to be of greater importance than atmospheric temperatures, as good growth can be made in hot atmospheres, provided the roots are kept relatively cool. There is some reason to believe that the minima are of as much importance as the maxima, i.e., that plants can withstand very high maximum temperatures provided there is a considerable drop to the minima, but cannot put up with the constant conditions of heat induced by fairly high maxima and high minima. III. Kharak Singh. ''Development of Root System of Wheat in Different Kinds of Soils and with Different Methods of Watering.'' Annals of Botanv, 1922. Vol. XXXVI. pp. 353-360. A study of the development of the root system in different kinds of soil and under varying conditions of manuring, watering, and cultivation, is of considerable importance in the Punjab (India), especially where the crops have to depend mainly on artificial irrigation. Duplicate pot experiments were carried out in which wheat plants were grown in various kinds of soil, watering being done on the surface in one case, and in the other through a small porous pot sunk to the level of the soil in the middle of each large pot, thus carrying the water directly to a lower level. The observations were preliminary in nature, but indicate that wheat plants in pots show better growth when watered from below than when watered from above. The difference is greater in light soil in the early stages of growth, but it is more marked in heavy soil in the later stages of growth. Under the exjjerimental conditions the development of root and shoot was best in pure sand, provided it was supplied with an adequate amount of water and was underlaid by a layer of farm- yard manure. The growth of wheat is better in a mixture containing 25 per cent, sand and 75 per cent. Rothamsted soil, than in pure Rothamsted soil, or in a mixture of 50 per cent, sand and 50 per cent. Rothamsted soil. Moreover, wheat plants do not I 31 grow well in brick powder even when underlaid with a layer of farmyard manure. IV. Violet G. Jackson. ''Anatomical Structure of the Roots of Barley." Annals of Botany, 1922. Vol. XXXVl. pp. 21-39. The root system of a well-developed barley plant, whether g-rown in soil or water culture, consists of two types of roots : (a) a thin branched type, and (b) a thick "unbranched" type, with very abundant root hairs. The present paper embodies the results obtained from, an anatomical investigation of the two types. A branched root possesses a much thickened stele with a single large axile vessel and six to eight xylem groups, all bounded by a very thick-walled endodermis. In an "unbranched" root neither the endodermis nor the stelar tissues are thickened, the xylem groups number from twelve to sixteen, and the middle of the root consists of thin-walled pith cells traversed by four to six ducts. The chief function of the "unbranched" roots is probably to provide the plant with a plentiful supply of water and its dissolved food, at the time when \igorous growth is setting in. This func- tion is provided for by : — (a) Abundant root hairs; (h) An increased number of large vessels and central ducts ; (c) The existence of a stele composed almost entirely of thin-walled elements. This view receives support from the fact that these roots are formed only during the early stages of the plant's vigorous growth. Researches on the development of root and shoot showed that the formation of "unbranched" roots had entirely ceased by time the plant had finished its vegetative growth and was entering on its reproductive phase. At this period of the plant's history, the nitrogen and ash constituents are migrating steadily from the straw into the grain, so that there is no need for a large root- absorbing area. On the other hand, if the "unbranched" roots functioned chiefly as buttress-roots, the plant would need thern even more when the heavy grain is being formed ; but that is just the time when their development ceases. Therefore the most probable function for the "unbranched" roots is to ensure a good supply of water, etc., when the plant is in a condition of strong vegetative growth. V. Katherine Warington. ''The Effect of Boric Acid and Borax on the Broad Bean and certain other Plants/' Annals of Botany, 1923. Vol. XXXVII. pp. 1-44. Boron appears to have some special function in the nutrition and development of the broad bean, as this plant fails to grow satisfactorily in nutritive solution from which boron is withheld. The results of the experimental work are: — 1. — In water culture a continual supply of boric acid appears to be essential to the healthy growth of the broad bean plant, concentrations of one part of boric acid (HgBO^) in 12,500,000 parts — 25,000 parts of nutrient solution being beneficial. In its absence, death occurs in a characteristic manner, the apex of the shoot becoming withered and blackened. The addi- tion of boric acid after these symptoms have set in, but before 32 death finally occurs, results in a renewal of g-rowth bv means of new lateral shoots and roots. This type of dying has not been observed in broad bean plants g-rown in pot culture, and it is concluded that suflicient boron is present, as a trace has been detected in the soils used. 2. — The absence of boron does not cause death in barley, gfrowth being healthy in ordinary culture solution. 3. — Excess of boric acid is poisonous to the broad bean, injury being apparent with one part of boric acid (H3BO3) in 5,000 parts of the water culture medium and with 0.5 gm. or 1.0 gm. per 22| lbs. of soil in pot culture, according to the method of application. 4. — Boric acid is more poisonous to barley than to the broad bean ; in water culture a concentration of one part of H3BO5 in 2,500,000 parts of nutrient solution, and in pot culture .5 gm. per 22|^ lbs. of soil is injurious. Smaller quantities are either in- effective or slightly favourable, though the benefit is usually evident to the eye only and not shown in the dry weight. 5. — Injury is marked by (i.) retardation of germination, (ii.) first chlorosis and later brown markings of the leaves ; the barley leaf becomes spotted but that of the broad bean shows a band of brown along the margins. (iii.) Retardation in maturing in the case of barley in soil culture. 6. — Preliminary experiments show that several other plants, and especially Pliaseohis multiflorus and Trifolium incarnatum, appear to benefit from the addition of small quantities of boric acid to the nutrient solution, though rye, like barley, is apparently indifferent to low concentrations. 7. — Boron is found to be present in considerable quantity in the dried shoots of the broad bean plants grown in a nutrient solution containing no boron, and also in the seed. In garden- grown plants a larger proportion of boron was present in the pods than in either the stems or leaves. No more than a trace was jdetected in the barley seed or in the dried shoots of untreated barley grown in water culture. 8. — It is suggested that the function of boron in the case of the broad bean is probably nutritive rather than catalytic, since a supply is required throughout the life of the plant. A parallel is drawn between the action of boron on plants and the \ itamines on animal life. VI. Kathekine Wakin(;ton. "TJie hijhiencc of Manuring on the Weed Flora of Arable Land/' journal of Ecology, 1924. Vol. XII. Examinations have been made of the weed species j^resent on the variously manured plots of fields which ha\e been cropped continuously for a considerable period with : — 1. Winter wheat (Broadbalk Field). 2. Spring barley (Hof)s Field). .3. Mangolds (Barn Field). The data show that the chief factors which determine the dominant species are the crop and the methods of cultivation, the most important weeds being quite different in the three fields. Winter fallowing has a particularly striking influence on the weed flora. 33 However, in the event of any serious deficiency such as an in- adequate nitrog^en supply, or a prolonged application of ammonium salts only, the influence of the manurial treatment becomes the most important factor and the flora undergoes modification of a similar nature irrespective of the methods of cultivation. In such cases a pereimial type of weed, as Equisetum arvense, Tussilago farfara or Cirsium arvense, was invariably found to predominate. Comparisons are between with the weeds recorded in 1867 on Broadbalk and Hoos fields and those found at the present day. Considerable reduction in the number of species has taken place in the former case, while changes in the individuals comprising the flora have occurred on both fields. The distribution and relative abundance of species and individuals are also described in the case of Broadbalk field. METHODS OF STATISTICAL EXAMINATION AND RESULTS. STATISTICAL TREATMENT OF SMALL SAMPLES. VII. R. A. Fisher. "On the 'Probable Error' of a Co- efficient of Correlation deduced from a small Sample." Metron, 1921. Vol. I., No. 4. pp. 1-32. Agricultural experiments deal almost invariably with a number of replicated plots, or parallel experiments, which is statistically small ; approximate methods suitable for large samples are there- fore liable to break down, and to lead to erroneous conclusions. This paper gives the exact form of distribution for correlation co- efficients obtained from small samples. By changing the scale upon which the correlation is measured, correlations from small samples may be treated with accuracy, and at the same time corrected for the small bias which is introduced by the standard methods of calculation. AGREEMENT OF THEORY AND OBSERVATION. VIII. R. A. Fisher. ''On the Interpretation of x", from Contingency Tables, and the Calculation of P." Journal of the Royal Statistical Society, 1922. Vol. LXXXV. pp. 87-94. Statistical tests of the agreement of series of experimental observations with any hypothesis, by which it is intended to inter- pret them, may be carried out by calculating the statistic ^^^ which measures the discrepancy. The distribution of -y^^, when the hypothesis tested is in fact true, can be calculated, and in this manner cases in which the discrepancy is excessive may be detected. In this paper it is shown that when the data to be tested have been used to construct the hypothetical expectation it is necessary to adopt a more severe test of agreement than that previously in use. This change of procedure, which particularly affects tests of independence in contingency tables, and of the goodness of fit of theoretical curves, may be simply and accurately effected by taking account of the number of degrees of freedom in which observations may differ from expectation, instead of merely the number of frequency classes. C 34 THKORV OV STATISTICAL KEDUCTIONS. IX. R. A. FiSHKK. "On the Mathematical Foundations of Theoretical Statistics/' Philosophical Transactions of the Royal Society, 1922. Vol. CCXXII. pp. 309-368. The main desideratum in the statistical reduction of data is that the statistics calculated shall include the whole of the informa- tion supplied by the data. It has been possible to put this requirement in a mathematical form, and so to lay down general conditions for the complete exhaustion of the data ; in particular it is possible to ascertain for any special statistical method pro- posed, of what percentage of the total information available it makes use. Many such tests are applied to current statistical methods, and in particular to the estimation of the numbers of soil protozoa by the dilution method. KAlNi-ALL IN BRITAIN. X. R. A. F'iSHEK and W. A. Mackenzie. "The Correlation of Weekly RainiaU." Quarterly Journal of the Royal Meteorolog-ical Societv, 1922. Vol. XLVIII. pp. 234-242. To study the effects of weather on crop production by means of simultaneous crop and weather records from different parts of the country, and thereby to reduce the number of years required for the accumulation of data comparable with the existing- Rothamsted records, it is necessary to know the correlation between the meteorolog-ical records of different stations. Such information is also necessary in repairing- defective records from those of neigh- bouring- stations, as also in estimating- weather conditions over local areas, such as river basins. This paper is a study of records from Aberdeen, York, and Rothamsted in respect of weekly rainfall. Even Rothamsted and Aberdeen 375 miles apart show a distinct positive correlation (average value .3717) in rainfall; the intermediate station, York, 150 miles from Rothamsted, and 225 miles from Aberdeen, gives average correlations .5898 and .5275. All three comparisons show well marked annual oscillations, the rainfall being most uniform in winter and least so in the early summer. Meteorologists suggest two possible causes for this novel phenomenon : (i.) the summer prevalence of local thunder- storms, (ii.) the more northern track of the summer cyclones. Whatever its cause, it is apparent that simultaneous crop and weather observations will throw light especially on the effects of summer rain or drought. PREDICTION FORMUL.^. XI. R. A. Fisher. "The Goodness of Fit of Regression Formula and the Distribution of Regression Co-effi- cients." Journal of the Roval Statistical Societv, 1922. Vol. LXXXV. pp. 597-612. Statistical predictions are based upon regression formulae, and their importance required that the correction established in Paper No. VI IT. (see above) should be applied in detail to such cases. It 35 was possible to find the exact distribution of the discrepancy between prediction and observation, and to render previous methods more exact in other points besides that mentioned above. In addition the true form of the distribution of the rej^^ression co- efficients was established, for which approximate forms only had been pre\iously a\ailable. IXMKKITANCK CORRELATIONS. XII. R. A. l^^isHKK. "On the Dominance Ratio/' I'roceed- ing-s of the Royal Society of lulinbur^^h, 1922. Vol. XLII. pp. 321-341. The effects of selection on the inheritance correlations show themselves in the dominance ratio. The value obtained from human measurements are all close to ^, and this value is not readily intellig-ible upon the simj^ler theory in which the effects of selection are ignored. When selection is taken into account it is demonstrated that the dominance ration will rise to ^, thus pro- viding the final step necessary to bring the whole of the existing correlation measurements in mankind itito harmony with the Mendelian theory of inheritance. CROSSOVER RATIOS. XIII. R. A. FisiiER. "T]ie Systematic Location of Genes hy means of Crossover Observations." American Naturalist, 1922. Vol. LVI. pp. -lOtMll. It is shown how the whole of the information supplied by crossover observations may be utilised in determining a consistent system of crossover ratios; the method is based upon that developed in Paper No. IX. (see above), and the working is analogous to that of a solution of least squares. ACCURACY OF BACTERIAL COUNTING. XIV. R. A. Fisher, H. G. Thornton, and W. A. Mackenzie, "Hie Accuracy of the Plating Metlwd of Estimating the Densitv of Bacterial Populations." Annals of Applied Biology, 1922. Vol. IX. pp. 325-359. As a rule, the accuracy of biometrical determinations must be ascertained empirically from a statistical study of the observations ; in certain cases, as has been shown in the theory of haemocytometer counts, the law of variation may be calculated, and the accuracy known with precision, provided the technique of the counting process is effectively perfect. A study of the extensive bacterial count data accumulated at Rothamsted by Cutler and Thornton, using Thornton's agar medium, indicated that the same law of variation, the Poisson series, was obeyed by the number of colonies counted on parallel plates. Statistical tests were devised which proved that, save for a small proportion of definite exceptions, the necessary perfection of technique was effectively realised. In studying the exceptional cases it appeared that these fall into two classes : (i.) an abnormally high variation which, when investigated experimentally, has been traced to certain bottom spreading organisms isolated from soil from Leeds and from Rothamsted, 36 and (ii.) an abnormally low variation ascribable to defective pro- cedure in the preparation of the medium. Application of the same tests to other extensive series of bacterial counts showed that a similar approach to theoretical accuracy, though rare, had been obtained by Breed and Stocking- in counts of B. coli in milk. It should be emphasised that all cases of departure from the theoretical law of distribution, which have been investigated, are associated with large systematic errors in the counts; for this reason simple tests are presented by which such deviations from the theoretical accuracy of the method can be detected. ACCURACY OF APHIS COUNTS. XV. R. A. FiSHEK. ''Appendix to 'Biological Studies of Appiis Rumicis,' by J. Davidson." Annals of Applied Biology, 1922. Vol. IX. pp. 142-145. A special method was developed for determining the accuracy of Dr. Davidson's counts on Aphids ; by this means it was possible to show that the 19 varieties of bean tested could be assigned to only six degrees of susceptibility to aphis infestation. MANUKIAL response OF POTATO VARIETIES. XVI. R. A. Fisher and W. A. Mackenzie. "The Manurial Response of Potato Varieties." Journal of Agricul- tural Science, 1923. Vol. XIII. pp. 311-320. In an experiment carried out at Rothamsted (1922), twelve potato varieties were each tested with six different manurial treat- ments, each test being triplicated. Consequently it was possible to test a question upon which very little information has hitherto been available, namely, whether different varieties respond alike to manurial treatment. It is impossible to generalise from a single test of a single species, and it has seemed to the authors of more importance to call attention to (i.) the kind of data required for such an enquiry, and (ii.) the type of statistical treatment needed to elicit an answer, than to emphasise the fact that no significant differences are observable in the manurial response, although the varieties differed much among themselves in yield, and the different treatments also resulted in large differences in yield. SOIL ORGANISMS. XVII. E. J. Russell, "l.es Micro-Orgaiiismes du Sol dans leurs rapports avec la croissance des plantes. Posi- tion actiielle du prohleme." Ann. de la Sci. Agro- monique, 1921. pp. 49-67. A review of the present position of our knowledge on this subject. ALG/E. XVIII. B. Muriel Bristol and Harold J. Page. "A Critical Enquiry into the Alleged Fixation of Atmospheric Nitrogen." Annals of Applied Biology, 1923. Vol. X. pp. 1-30. 37 Four species of green algae were grown in pure culture on six media which had as a common basis a solution of mineral salts devised by Schramm, but differing- in that the nitrogen was supplied as ammonium nitrate, calcium nitrate or ammonium sulphate ; for each of these sources of nitrogen there were two media, one without added sugar and the other containing 1% glucose. The cultures were aerated daily with sterile air free from combined nitrogen. The initial nitrogen-content of the medium in each flask was ascertained from check analyses of that medium, and the nitrogen-content after six months' growth was determined by chemical analysis of the whole of the contents of the flask. In practically all cases a good growth of algae was obtained, and in a large number the growth was luxuriant. Nevertheless the analytical results afforded no evidence whatever that any fixation had occurred. In fact, those cultures the growth of which had been most luxuriant had a final nitrogen-content that was, if anything, slightly lower than that of the medium originally. This result differs from that obtained by Wann (Amer. Jour. Bot., 1921., Vol. VIII.) Investigation showed, however, that the method by which he estimated nitrogen breaks down in presence of nitrate. The results give the appearance of nitrogen fixation even when none occurred. The chemical methods used by the present authors were free from these sources of error and, as already stated, no fixation could be detected. While it is quite conceivable that green algae might under certain conditions, as yet unknown, assimilate atmospheric nitrogen, there is so far no trustworthy evidence that they can do so. BACTERIA. XIX. H. G. Thornton. "On the Developmeyit of a Standardised Agar Medium for Counting Soil Bacteria, with especial regard to the Repression of Spreading Colonies." Annals of Applied Biology, 1922. Vol. IX. pp. 241-274. For counting bacteria by the plating method it is a first essen- tial to accuracy that the plating medium should give uniform results. The medium should be exactly reproducible, i.e., different batches should give similar results. In the medium here develcped, this has been achie\ed by using pure chemical compounds as food constituents, selecting those compounds that did not alter the re- action of the medium during sterilisation. Further parallel platings of a suspension of organisms made on a single batch of medium should develop the same number of colonies (within the limits of random sampling variance). This necessitates the independent development of each colony on the plate, which on agar media is frequently prevented by the develop- ment of bacteria that form rapidly spreading colonies which interfere with the development of other bacteria. A special study was therefore made of a common ''spreading" organism with a view to limiting its growth. It was found that the organism spreads over the agar surface by active motility and that the factors controlling its spread were (i.) the existence of a 38 surface film of water on the ag'ar, and (ii.) the rate of multiplica- tion previous to the drying- of this film. In the present medium this rate of multiplication has been much reduced so that spreading- colonies are greatly restricted. The medium has the following composition:— K.HPO^, 1.0 gram; MgSO^, 7 H.O, 0.2 grs. ; CaCU, 0.1 gr. ; NaCl, 0.1 gr. ; FeClg, .002 grs. ; KNO3, 0.5 grs. Asparagine, 0.5 grs. ; mannitol, 1.0 gram; agar, 15.0 grs. ; water to 1000 cc. Reaction brought to Ph 7.4 before sterilisation. (For the rigid test of this medium, see Paper XIV., p. 35.) PROTOZOA. XX. D. W. Cutler, Lettice M. Crump, and H. Sandon. ''A Quantitative Investigation of the Bacterial and Protozoan Population of the Soil," Phil. Trans. Roy. Soc, London, B., 1922. Vol. CCXI. pp. 317-350. The results of 365 consecutive daily counts of the numbers of bacteria and of six species of protozoa in a normal field soil are given, and the methods of counting bacteria and protozoa are described. The numbers of both bacteria and protozoa rarely remain the same from one day to the next. The fluctuations are very great, but it has not been found possible to connect them with meteoro- logical or general soil conditions. Fourteen-day averages of the daily numbers demonstrate that well-marked seasonal changes in the soil population are super- imposed on the daily variations in numbers. In general, both bacteria and protozoa are most numerous at the end of November and fewest in February. These changes are not directly influenced by temperature or rainfall, but show a similarity to the seasonal fluctuations recorded for many acquatic organisms. There is a slight tendency for the various species of flagellates to fluctuate together from day to day, but this is not shown by the two species of amoebae. An inverse relationship is found between the numbers of bacteria and active amoebai in 86% of the total observations. A two-day periodicity obtains for the active numbers of one species of flagellate {Oiconionas termo). XXI. D. W. Cutler. ''The Action of Protozoa on Bacteria when Inoculated into Sterile Soil." Annals of Applied Biology, 1923. Vol. X. pp. 137-141. Soil sterilized by heat was inoculated with : — (a) Bacteria alone ; (h) ,, + one species of amoeba; (c) ,, + one species of flagellate. Daily bacterial counts made on each portion of soil showed that the one containing no protozoa sustained a greater number of bacteria than those containing protozoa. Also the bacteria in the |)rotozoa free soil did not exhibit the fluctuations in numbers characteristic of soil in which protozoa were living. 39 XXII. S. M. Nasir. "Some Preliminary Investigations on the Relationship of Protozoa to Soil Fertility with Special Reference to Nitrogen Fixation/' Annals of Applied Biology, 1923. Vol. X. pp. 122-133. A perusal of the results shows that the presence of protozoa has no depressing- effect on the nitrogen-fixing bacteria, either in the artificial culture media, or in sand cultures. From a total of 36 experiments done in duplicates or triplicates, 31 showed a decided gain, while only 5 gave negative results. The average figure for fixation works out to be 8.5%, which is well above the experimental error. The highest fixation of 30.04% was recorded in sand cultures in the case of ciliates. All the three types of protozoa gave higher fixation figures. The experiment was repeated six times, and every time concordant results were obtained. XXIII. D. W. Cutler and Lettice M. Crump. "The Rate of Reproduction in Artificial Culture of Colpidiiim Colpoda/' Biochemical Journal, 1923. Vol. XVII. pp. 174-18(). Methods are given by which it has been found possible to obtain comparable results when studying the reproductive rates of certain protozoa in mass cultures. It is shown that within a relatively short period after inocula- tion, under certain conditions, a varying proportion of the organisms die ; and that this is correlated with the age of the culture from which the inoculation was made. By means of three hourly counts it was found that death occurs even during the period of maximum reproduction. Evidence is supplied that in certain strains of Colpidium the rate of reproduction from inoculation to the maximum numbers attained is constant. XXIV. Madhi.kink Pekev. "Les Protozoaires du Sol/* Ann. Sci. Agron., 1923. Vol. LXIII. pp. 333-352. A short review is given of our knowledge of soil protozoa together with an account of the species of protozoa found in certain French soils. XXV. H. Sandon. "Some Protozoa from the Soils and Mosses of Spitsbergen/' Journ. Linn. Soc, 1923. Vol. XXXIV. Samples of soils and mosses brought back from Spitsbergen by the Oxford University expedition of 1921 and 1922 were examined, and an abundant protozoal fauna, practically identical with that found in soils and mosses of temperate lands, was found. Protozoa were found to be considerably more numerous in some of the soil samples than in others, but no close connection could be found between the numbers of species present and the physical or chemical properties of the soils. Descriptions are given of seven previously undescribed flagellates, of which five, however, occur also in Rothamsted soils. 40 FACTORS DETERMINING ENVIRONMENTAL CONDITIONS. XXVI. E. j. Russell. "Hie PJiysico-Chemical Problems relating to the Soil.'* Trans. Faraday Society, 1922. Vol. XVII. pp. 219-22:1 A g-eneral survey of the physico-chemical factors operating in the soil and their influence on fertility. The soil is regarded as a system formed of four components : (i.) mineral particles; being- disintegrated and decomposed rock fragments which, through the action of weather, water, ice and other factors, have in course of time been reduced to dimensions varying from about 1 mm. in diameter to molecular orders of magnitude. (ii.) Colloidal material ; either very fine particles or a jelly coating the larger particles and consisting of materials such as precipitated oxides of iron and aluminium, silicia, etc., or both, (iii.) Intermingled in most intimate fashion with this is the organic matter, residues of past generations of plants and animals, which represents the source of energy for the large population of soil organisms, (iv.) The soil solution, being the soil w^ater and everything dissolved therein. The whole mass is permeated with air. It is shown that the agricultural and physical properties of the soil can to a considerable extent be explained by such a system, but there are facts which do not as yet readily fit it. A more detailed discussion of certain aspects of the subject is given in the following three papers. XXVII. H. J. Page. "The Part Played by Organic Matter in the Soil System." Trans. Faraday Society, 1922. Vol. XVII. pp. 272-287. The influence of the humic material of the soil, on the physical and physico-chemical properties of the soil is discussed. Owing to the colloidal nature of this humic material, its chemical nature and mode of formation are still little understood. The established agricultural practice of using dung, green manures, etc., to maintain the fertility of the soil, however, depends in a large degree on the colloidal nature of the humic material derived from such organic manures ; even without more knowledge of the chemical nature of humus, its effect on tilth, moisture relationships, supply of plant nutrients, and soil reaction can be explained, at any rate on broad lines, in terms of its physical, i.e., colloidal, properties. XXVIII. B. A. Keen. "The System Soil— Soil Moisture." Trans. Faraday Society, 1922. Vol. XVII. pp. 228-243. A general discussion of the relations existing between the soil and its moisture content, with especial reference to the physical significance of the various divisions of soil moisture that have been proposed from time to time. XXIX. E. M. Ckowthek. "Soil Acidity in its Physico- Chemical Aspects." Trans. Faradav Society, 1922. Vol. XVII. pp. 317-320. 41 A g-eneral discussion of the methods used for the determination of the acidity and lime requirements of soils, with especial reference to the hydrogen-ion concentration of soil suspensions and the action of neutral salts on acid soils. XXX. W. B. Haines. "The Volume-Changes Associated with Variations of Water Content in Soil." Journal of Ag^ricultural Science, 1923. Vol. XIII. pp. 296-310. A new and simple method of measuring- the shrinkag^e of moist soil on drying- is described, which at the same time g-ives values for the pore space and specific g-ravity of the soil. Diag^rams are g-iven showing- the characteristics of the shrinkag-e for diverse samples, including^ pure clay, heavy loam, sandy and peaty soils. The shrinkag^e is shown to take place in two stages, in both of which there is a linear relationship to the moisture content. The first stage is largely governed by the clay-content of the soil and its limit is fixed by the point at which air begins to replace water in the pores of the soil. The second stage, called the residual shrinkage, is smaller than the first, and seems to depend upon the more highly colloidal material which has been supposed to surround the clay and other particles. Explanation of the shrinkage is developed on these lines with confirmatory experiments. The effect of alternate wetting and drying of soil in producing a good tilth is illustrated. XXXI. B. A. Keen and H. Raczkowski. "The Relation between the Clay Content and Certain Physical Properties of a Soil.*' Journal of Agricultural Science, 1921. Vol. XI. pp. 441-449. A simple experimental method has been described for measur- ing certain physical constants of soil, using small brass boxes into which soil passing a sieve of 100 meshes to the inch has been packed by hand. The quantities determined are : — 1. The weight of unit volume (1100 ccs.) of air-dry soil, or the apparent specific gravity. 2. Amount of water taken up by unit weight of soil. 3. Pore space. 4. Specific gravity of the soil. 5. The volume expansion of unit volume (100 cc.) of soil when saturated. The results for one soil only are given, and discussed, to illustrate the method. With the co-operation of the Science Masters' Association it is being applied to a number of soils by various schools. The particular soil used was obtained in six depths, as follows : 0-6", 6-12", 12-18", 2-3', 3-4', and the constants were determined in each depth. It was shown that 1 and 4 varied inversely with the percentage of clay in the soil, while 2, 3, and 5 varied directly with the clay percentages. The effect on the constants of the larger quantities of organic matter present in the top two layers of soil was, weight for weight, approximately equal to that of the clay, except in the volume expansion results where the effect, if any, was within experimental error. 42 It is possible that the fraction fine silt II., whose upper limit of diameter is .005 mm., has similar effects to the clay fraction. XXXII. B. A. Keen. "Evaporation of Water from Soil II. Influence of Soil Type and Manurial Treatment." Journal of Agricultural Science, 1921. Vol. XI. pp. 432-440. Further experiments have been done on the evaporation of water from soil, using- the same apparatus and technique as described in an earlier paper. The present series of experiments was desig-ned to investigate the effect of clay content and manurial treatment on the evaporation. Two soils have been used, one containing only 6% clay and the other 15%, and from each soil samples were taken from plots which had received (a) no manure, (h) artificial manure, (c) farmyard manure. The rate at which the soils lost water over concentrated sulphuric acid and at a constant temperature was found to depend firstly on the amount of clay present, and secondly on the amount of organic material in the soil. The differences due to content of organic material were more obvious in the soil containing the larger amount of clay ; the farmyard manure plot lost water at the slowest rate, and the un- manured plot occupied an intermediate position. In the sandy soil the differences in evaporation due to manuring were small. There is evidence that the moisture equivalent of these soils measures the percentage of water at which the evaporation is first directly affected by the soil particles, and that at percentages of water in excess of the moisture equivalent evaporation is taking place substantially from a free water surface. XXXIII. E. J. Russell and B. A. Keen. ''The Effect of Chalk on the Cultivation of Heavy Land." Journal of Ministry of Agriculture, 1922. Vol. XXVIII. pp. 419-422. Measurements taken with a dynamometer showed that dress- ings of chalk applied 8 years ago were still effective in facilitating cultivation, the saving of drawbar pull being in these trials no less than 180 lb. on a three furrow plough (see p. 12). THE PLANT IN DISEASE. INSECT PESTS AND THEIR CONTROL. XXXIV. A. D. Imms. "Recent Research on the Head and Month-parts of Diptera.'" Entomologist's Monthly Magazine. 3rd Series, 1920. Vol. VI. pp. 106-109. A short discussion of the subject from the morphological standpoint. XXXV. J. Davidson. "Biological Studies of Aphis RuMicis Linn. IV. Reproduction on varieties of ViciA Faha — with a Statistical Appendix by R. A. Fisher." (See No. XV.) Annals of Applied Biology, 1922. Vol. IX. pp. 135-145. The reproduction of the bean aphis on 18 \arieties of field beans was tested and compared with reproduction on Prolific Longpod broad beans. 43 The mean values of infestation for the varieties ranged from 37 to 1,037. These values allow of the varieties being- tentatively grouped into classes representing various degrees of susceptibility ranging from 98% to 3%. The results obtained indicate that resistance or susceptibility may be largely determined by genetic (actors in the plant. XXXVI. J. Davidson. "Biological Studies of Aphis RuMicis Linn. V. The Penetration of Plant Tissues and the Source of the Food Supply of Aphids." Annals of Applied Biologv, 1923. Vol. X. pp. 35-54. The food of aphids is the juices of plants which they obtain by penetrating the tissues by means of a delicate piercing organ formed by four chitinous stylets. The piercing organ passes between the cortical cells — occa- sionally through intlividual cells — to the vascular bundles. The saliva secreted by the aphis acts on the middle lamella of the cell wall. It also causes plasmolysis of the cells; and it is able to convert starch into sugar. The phkfim tissue is the chief source of the food supply, but other cells of the plant, such as cortex and mesophyll, may be tapped for nourishment. The sucking out jjroiX'ss is usually intracellular, although in- tercellular suction sometimes goes on. The varying physiological constitution of different plants or even varieties of the same sjiecies of plant is important in relation to the biology and physiology of aphids. The comjK)sition of "honey dew" — the sugary excrement of aphids — is in close relationship with the |);irti tlie value is 5% bushels, t For early and late dressings respectively. Phosphates were curiously ineffective in 1922, even on the sv/ede and barley crops where one would have expected them to act well. During the early part of the season the usual effects of stimulation of early growth were produced. Barley and swedes receiving phosphates both started earlier into growth, and the swedes were sooner ready for hoeing than where phosphate was withheld. Potassic fertilisers, on the other hand, proved very effective. Even barley responded (which does not usually happen at Rothamsted), and the response was as marked as that of nitrogen (which is c\en more unusual). The effect on potatoes was very 59 marked, especially where no dung was applied, and formed one of the most striking- demonstrations of the year. Some of the figures were : — Barley Poiaioes (Kerr's Pink bush. tons per acre No Dung Dung .32. (; 8.3 9.5 27.0 2.5 8.0 Complete manure No potash The Barntield mangolds were in May badly attacked by a small beetle, Atomaria linearis, which seriously affected all plots except those receiving- rape cake. EXI^ENDITURE AND CASH RETURNS PER ACRE. The classical fields of the farm are used continuously for their appropriate experiments, but the remaining- fields are not. After an experiment is completed the land goes back to ordinary cultiva- tion so as to restore uniformity of conditions as far as possible. Usually about 170 acres are thus farmed. The accounts for this farmed land are kept quite separate from those for the experimental areas, and they show approximately what an ordinary farmer might spend and receive. The figures are worked out by precisely the same method as in the last report. They include only money paid out or brought in ; there are no allowances for interest or farmers' remuneration beyond .£175 per annum, which is spread over 178^ acres; also no allowance is made for residual manurial values. Depreciation of horses and dead stock is, however, included. Wheat Oats . Barley . Roots . Potatoes Clover . Grass : Temporary hay Permanent hay ExPENPiTURE Per Acre. Oct. 1920- Sept. 1921 16 12 19 19 38 17 47 11 Oct. 1921- Sept. 1922 £ s. 11 4 10 10 12 16 31 5 5~9t Cash Returns Per Acke. Oct. 1919- Sept. 1921* Oct. 1920- Sept. 1921 Oct. 1921- Sept. 1922 £ s. 6 12 11 11 6 1 17 16 8 16 Wheat . . . . Oats . . . . Barley . . . . Roots . . . . Potatoes . . . . Clover . . . . Grass ; Permanent hay . Temporary hay . Total farming loss Cash Balancb (+) or Deficit (— ) Per Acre. Oct. 1919-Sept. 1920 jr + "5 + 4 + . —31 + . 16 - 1 11 I Profit ) £410 ( (176 acres^ ' Oct. 1920-Sept. 1921 — 2 — 4 —17 —29 — 3 — 1 •^ct. 1921-Sept. 1922 £960 - 16 (173 acres) £308 - 11 (140 acres) * As stated in the 1918-20 Report, the figures there given include the estimated value of unsold material. Ihe sales are now complete and the final figures are given here. + Carried on from 1921: see p. 56. From 1920 onwards the financial results are deplorable, and they show clearly why many of the arable farmers to-day are in their present position. 60 DETAILS OF PLOUGHING COSTS. Cost of Ploughing One Acre of Land. Horses. Tractor. 1921 21 hours @ 9id. = 17/- Ploughman : \\ days @ 8/5 = 12/7 Implements 2/- 1922 @ 7d. = 12/3 @ 4/lOid =7/3 1/6 1921 3 hours @ 4/- == 12/- Driver . 3 ., @ l/2i= 3/7 Implements 2/6 1922 @ 3/6 = 10/6 @10d.= 2/6 2- 31/7 21/- \^l\ 15/- Approximate Paraffin and Oil Consumption for Ploughing 3 Furrows. Austin Titan Paraffin per acre 2 to 3 gals. : 3i-4f gals. : averag-e 21 average 4^ per hour : approx. 1 gal. H gals. Oil per acre 0.06 gals. .66 gals. Time to plough one acre about . . 21 hrs. 3 hrs. The farm manager supplies the following notes on the tractors during the season 1921-22. Hours of Work. Paraffin consumed at above rates. Oil Consumed.* Petrol Consumed. Austin . . . Titan . . . 8354 247i 8354 gals. 3714 „ 17 gals. 31 „ 1 54 gals. Totals . 1354 days 1207 gals. 48 gals. 54 gals. * Calculated at average rates for Austin 1 gal. per wk., Titan 1 gal. per day. The consumption of paraffin per hour seems to be the most constant factor for purposes of calculating. The difference in the cost of various operations is brought about mainly by the width of the implement used and the speed maintained. The number of hours exclusive of threshing = 870 or about 109 working days, equivalent to 6,090 horse hours, 2f horses per annum. While a horse may put in 280 days' work, a good deal of this is of a maintenance type and not strictly seasonal. The tractor hours probably represent the time put into the important work of the farm by 3-1 horses. Types of work done : — Ploughing Sub-soiling. Cultivating. Drag + harrow. Overhauling at end of season :- Parts. . .£3 11 8 (supplied free). Labour . £11 0 0 Roller + harrow. Roller only. Cutting and bindinj..j. Threshing. 61 WOBURN EXPERIMENTAL FARM. REPORT FOR 1922 by Dr. J. A. VOELCKER. Season. Beg-inning with a warm, dry October 1921, autumn cultivation and sowing made good progress. The winter was marked by little rain and only occasional frosts ; it was followed by a cold and sunless spring which retarded the growth of winter-sown crops, and by a very wet April which delayed the sowing of spring crops. The early part of May was cold and wet, the latter hot and dry, this continuing throughout June and making the obtaining of a good swede crop difficult. In July rainfall was excessive, and, from then to harvest, cold and wet weather, with absence of sunshine, prevented the proper ripening of corn crops, all being considerably damaged by rain. Mangolds, being put in early, were an excellent crop, as also Potatoes, but Swedes were almost an entire failure, and Hay, though a fairly large crop, was not of good quality. The rainfall for the season was 25.41 inches, there being 193 days on which rain fell. The rainfall was heaviest in July (4.02 ins.), and in April (3.89 ins.); in August and September, 2.07 ins. and 2.48 ins. of rain fell. FIELD EXPERIMENTS, 1922. 1. Contiyinous Gr(nvin(r of IF/zeai (Stackyard Field), //6'th Season. "Red Standard" wheat (10 pecks to the acre) was drilled on October 10th, 1921. Farmyard manure (plot 11 B) was ploughed in on October 5th, Rape Dust (plot lOB) on October 8th, and mineral manures given to the several plots at the time of drilling the wheat. The nitrogenous top-dressings were put on- May 17th and June 17th, 1922. The wheat crop was cut on August 11th, stacked August 29th, and threshed on December 22nd. The results are given on page 62. The crop results were very similar to those of 1920. The main features shown are : — The unmanured produce averaged 8.5 bushels of corn with 7 cwt. of straw per acre; farm- yard manure gave only 2 bushels more per acre, Rape Dust doing 62 Continuous Growing of Wheat, 1922 {J/6'th Season) . (Wheat grown year after year on the same land, the manures being applied ov(!ry year.) Stackyard Field-^Produce per acre. Head Corn Tail corn Straw. Plot. Manures per acre. No. of Weight chaff. bushels. per bushel. 'v lb. 11). cwt q. lb. 1 Unmanured ..... 8.9 59.7 8 8 0 16 2a Sulphate of ammonia (=^25 lb. am- monia) 1.4 60 — .- 1 2 24 2aa As 2a, with 5 cwt. lime, Jan., 1905. repeated 1909, 1910 and 1911 8.8 60 12 8 2 0 2b As 2a. with 2 tons lime, Dec, 1897 . 10 60- 2 9 1 26 2bb As 2b, with 2 tons lime (repeated), Jan , 1905 9.4 60 6 8 0 8 3a Nitrate of soda ( = 50 lb. ammonia) 13.8 58.2 18 12 2 0 3b Nitrate of soda ( = 25 lb. ammonia) 13.4 59.7 10 11 1 12 4 Mineral manures (superphosphate, 3 cwt.; sulphate of potash, I cwt.) . 7 7 60 6 9 0 16 5a Mineral manures and sulphate of am- monia ( = 25 lb. ammonia) . 14 1 61 12 14 1 24 5b As 5a, with 1 ton lime, Jan., 1905 16.7 61 8 16 3 16 6 Mineral manures and nitrate of soda ( = 25 lb. ammonia) 14.0 60.2 8 13 2 2 7 Unmanured 8.1 60 7 4 6 2 0 8a Mineral manures and (in alternate years) sulphate of ammonia (^50 lb. ammonia) .... 4.8 60 36 7 2 24 8aa As 8a, with 10 cwt. lime. Jan , 1905, repeated Jan.. 1918 9.9 60 12 10 1 12 8b Mineral manures, sulphate of am- monia ( = 50 lb. ammonia) omitted (in alternate years) 3.8 60 — 4 2 16 8bb As 8b, with 10 cwt. lime, Jan., 1905, repeated Jan., 1918 9.9 60 16 11 0 0 9a Mineral manures and (in alternate years) nitrate of soda ( =50 lb. ammonia) 11.3 59.2 4 11 2 14 9b Mineral manures, nitrate of soda ( = 50 lb. ammonia) omitted (in alternate years) .... 8.0 61.2 6 9 1 0 10a Superphosphate 3 cwt., nitrate of soda ( = 25 lb. ammonia) 18.3 60 12 16 0 0 10b Rape dust ( = 25 lb. ammonia) . 13.5 61 8 13 0 24 11a Sulphate of potash 1 cwt.. nitrate of soda ( = 25 lb. ammonia) 11.8 60 8 14 3 16 lib Farmyard manure (=100 lb. am- monia) 10.8 59.7 8 13 2 20 better (5 bushels increase); the highest crop was 18.3 bushels of corn j>er acre from superphosphate and nitrate of soda, the next best, 1G.7 bushels, being- from minerals and sulphate of ammonia, with lime. Apparently the 10 cwt. per acre of lime applied last in 1918 to plots 8aa, 8bb, was nearl}- worked out, but the 1 ton per acre (plot 5b) continued to show an influence, as did, to a slight extent still, the 2 tons (plot 2b) given as far back as 1897. 63 2. Cofitiniiotis Growing of Barley (Stackyard Field), 46th Season. Owing to the wet state of the land it was not possible to drill the barley until April 18th, 1922, when "Plumage Archer" (10 pecks per acre), was sown, the mineral manures going on at the same time. Farmyard manure had been previously (March 13th) ploughed in on plot IIB, and Rape Dust (plot lOB) applied on April 12th. The nitrogenous top-dressings were given on June 17th and July 3rd. The barley, despite an unfavourable season, grew better than usual; this may in no small measure be due to selected seed being used; indeed, the variety ("Plumage Archer") proved, over the farm generally, to answer considerably better than the other varieties, "Bevan's Archer" and "Chevalier," also grown. The newly-limed plots (3aa and 'ibb, limed January, 1921,) seemed, from the outset, to be better than the unlimed. The crop was cut on September 11th, stac^ked October 11 th, and threshed on December 21st. The results are given on page 64. The crop was the highest recorded since 1917, the unmanured produce being l.'^.T) bushels of corn and 9^ cwt. of straw per acre. The highest yield was .'58. 'i bushels of corn per acre, with farmyard manure; the next highest, 33.8 bushels, with minerals and nitrate of soda. Unlike with wheat, rape dust gave but a poor crop. As in previous years, the use of potash (plot 11a) seemed to benefit the barley more than that of phosphate. The most striking results, however, are those showing the influence of lime. Not only have there been notable increases in plots 2B, 2BB, 5AA, 5B, 8AA, and 8BB, as compared with the corresponding unlimed plots, but, where lime was put on plots previously treated for many years with nitrate of soda, there was a marked restoration of the yield, though the lime had only gone on the year previous. It would appear from this that not only where sulphate of ammonia is used continually is lime a necessity, but that lime will also tell where nitrate of soda has been similarly used. It should be mentioned that some of the barley area was attacked by "gout-fly," and this was investigated on the spot by Mr. Frew, of the Entomological Department. The plots least affected were the ones most highly manured. 64 Continuous Growing of Barley, 1922 {J/6th Season). (Barley grown year after year on the same laml, the manures being applied every year.) Stackyard Field — Produce per acre. Head Corn Tail corn Straw Plot Manures per acre No. of Weisht 1 chafif. ' &c. bushels per bushel lb. lb. cwt. qr. lb. 1 Unmanured .... 14 9 49.5 19 10 2 18 2a Sulphate of ammonia (= 25 lb. am monia) .... 4.9 54 — 2 3 12 2aa As 2a, with 5 cwt lime, Mar., 1905 repeated 1909. 1910, and 1912 6.3 56 5 1 8 2b As 2a, with 2 tons lime, Dec. 1897 repeated 1912 23.6 48.2 40 13 0 24 2bb As 2a, with 2 tons lime, Dec, 1897 repeated Mar., 1905 . 24.0 48.2 40 10 3 24 3a Nitrate of soda ( = 50 lb. ammonia) 11.4 51 28 6 3 12 3aa As 3a, with 2 tons lime, Jan., 1921 23.0 47.2 32 16 0 4 3b Nitrate of soda (-=25 lb. ammonia) 17.3 48.2 32 8 3 8 3bb As 3b, with 2 tons lime, Jan., 1921 21 4 47.5 44 10 0 16 4a Mineral manures' 18.0 49.7 24 10 3 26 4b As 4a, with 1 ton lime. 1915 19.3 49.7 30 11 1 16 5a Mineral manures and sulphate o ammonia ( = 25 lb. ammonia) 13.6 50 24 9 1 8 5aa As 5a, with 1 ton lime. Mar. 1905 repeated 1916 28.8 49.7 44 14 1 4 5b As 5a. with 2 tons lime, Dec 1897 repeated 1912 26 9 48.4 42 15 3 0 6 Mineral manures and nitrate of soda ( = 25 lb. ammonia) 30 0 48.5 46 16 0 9 7 Unmanured .... 12.6 48.7 20 8 2 12 8a Mineral manures and (in alternate years) sulphate of ammonis ( = 50 lb. ammonia) 2.0 50 0 3 12 8aa As 8a, with 2 tons lime, Dec, 1897 repeated 1912 26 2 48.7 56 16 3 16 8b Mineral manures, sulphate of am monia (=50 lb. ammonia) omittec (in alternate years) 13 50 — 1 0 0 8bb As 8b, with 2 tons lime, Dec, 1897 repeated 1912 17.7 50.5 24 12 3 0 9a Mineral manures and (in alternate yeats) nitrate of soda (=50 lb ammonia) .... 33.8 47.3 76 19 2 6 9b Mineral manures, nitrate of sods ( = 50 lb. ammonia) omitted (ir L f alternate years) . 27.3 48.5 34 14 1 18 10a Superphosphate 3 cwt. , nitrate of sode I ( = 25 lb. ammonia) 25.1 47 - 46 14 1 26 10b Rape dust ( = 25 lb. ammonia) . 10.8 49 26 7 2 4 11a Sulphate of potash 1 cwt., nitrate o f soda ( = 25 lb. ammonia) 29.1 49 44 17 3 24 lib Farmyard manure (=100 lb. am monia) ... 38.3 49.6 78 19 2 20 ^ Superphosphate 3 CWt., sulphate of pota.sh | cwt. 65 3. Rotation Experiments. The Unexhausted Manurial Value of Cake and Corn (Stackyard Field). (a) Series C, 1922. Swedes. The previous rotation being- concluded with wheat (1921) following- red clover, swedes were put in as the first crop of the new rotation. The drought towards the end of May and through- out June made the swede crop very uncertain ; the seed was drilled on June 18th, mineral manures (superphosphate 3 cwt., sulphate of potash 1 cwt., per acre) being applied shortly before (May 26th). A plant was, with difficulty, obtained, and a small crop, though uniform over the area, was grown. A top-dressing of 1 cwt. per acre nitrate of soda was given after singling. The crop was, later on, fed off with sheep, one half with cake, the other half with corn. (b) Series D, 1922. Barley after Swedes. The swede crop of 1921 being too small to feed off on the land, it was removed, and barley ("Beaven's Archer") drilled on April 11th, superphosphate 2 cwt. per acre and sulphate of potash 1 cwt. per acre having been applied April 7th. 1 cwt. sulphate of ammonia per acre was given later as a top-dressing. Red clover was sown in the barley on May 22nd. The barley was only a moderate crop and was cut on September 30th. It took a long time to cart, owing to bad weather, but was ultimately stacked October 11th, and was threshed December 10th. The results follow. Rotation Experiment — the Unexhausted Manurial Value of Cake and Corn. Series D (Stackyard Field), 1922 — Barley after Swedes {carted off) . Plot Head corn Tail corn Weight. Straw. chafif. etc. Bushels. Weight per Bushel. 1 2 Corn-fed Plot . . i 22.3 Cake fed Plot .... 20.3 lb. 47.5 49 lb. 42 52 cwt. qr. lb. 10 1 24 9 3 3 The yield was poor, and not equal to the manured plots of the continuous barley series in the same field, where, however, "Plumage Archer" had been grown as against "Beaven's Archer" here. Moreover, the yield after feeding of corn was somewhat above that after feeding of cake. 4. Green Manuring Experiments^ (a) Stackyard Field. Series A. After the growing of gr^en crops (tares and mustard) in 1921 it was decided to make a change in these plots, the whole area of 4 acres being divided into an upper and a lower half, and a re- arrangement made by which, while the alternation of green crop and corn crop was kept up, there should be every year one half in E 66 green crop and the other half in corn. P^urther, it was decided to limit future enquiry to the two green crops, tares and mustard, both in this field and in Lansome Field, and to omit the third crop, rape. Accordingly, after the g-reen crops of 1921 had been fed off by sheep, wheat was sown over the lower 2 acres, and green crops again on the upper 2 acres. Wheat (*'Red Standard") was drilled on October 12th, and winter tares on 1 acre on October 12th. Mustard followed on the remaining 1 acre on Mav 27th, 1922. It was very noticeable that the tares were markedly better on that part of the land where in earlier years (since 1911) rape had been grown, than where tares followed tares ; a like difference was seen on the lower half with the wheat crop, this being better on the strip that had carried rape than where tares had been the crop. This would seem to open a question as to whether the repetition of the tares crop had not had an injurious effect. The wheat, following green crops fed on, made little progress, and was a very disappointing crop. It was cut on August 24th, stacked, and threshed December 22nd. The results follow. Green Manuring Experiment (Stackyard Field). Produce of Wheat per acre, 1922 — after Green Crops. Series A. Head Corn Tail Corn Straw. Plot Bushels. Weight per Bushel Weight Chaff, etc. 1 2 After Tares fed off . After Mustard fed off 6.9 7.5 lb. 60 5N.6 lb. 5 6 cwt. qr. lb. 7 3 3 8 2 3 These poor results are quite unaccountable, especially when it is remembered that on land only a few yards off in the same field the unmanured yield after ii) years was higher than here. More- over, not only had very fair green crops been grown in 1921, but these had been fed off by sheep which had H cwts. of cotton cake per acre as well. This opens up a whole series of problems in relation to green manuring, nnd which call for careful investiga- tion. The tares on the upper half grew well, were fed off by sheep, in July, 1922, receiving '^ cwt. cotton cake per acre, and then a second crop of tares was grown, this being similarly fed off along with cake in October. Mustard, sown on May 27th, was fed off with cotton cake, a second crop then grown and this likewise fed(^ff. (h) Lansome Field. Green crops of tares and mustard had been grown on the old plots of this experiment in the summer of 1921, and were ploughed in towards the end of July. The area was then extended by the addition of >) more |-acre plots, one of tares, one of mustard, and the third left as a control plot. To all the plots alike (now f) in 67 number) basic slag at the rate of 5 cwt. per acre, and sulphate of potash 1 cwt. per acre, were given on October 14th, 1921, and tares and mustard again sown. These did not come to much, and so the land was cleaned and green crops again put in on June 28th, 1922, when they grew much better; the mustard was ploughed in August 2(Sth and the tares October 16th, wheat then being drilled over the whole area. 5. Malting Barley Experiments. Experiments were carried out, in conjunction with Rothamsted and other centres, on the influence on yield and quality produced with barley by different manures and combinations of these. The variety of barley supplied was "Plumage Archer." (a) Warren Field. The field selected at Woburn was the heaviest one on the farm, the soil being a fairly heaxy sandy loam, just on the junction of the Lower Greensand and Oxford Clay formations. Previously the land had grown a crop of mangolds which had had )(liic(' of Barlf'V per ;icro, nflor M;iii,;^o1(ls (niaiuirod) . Head Corn Tail Corn Manures per acre Straw, Plot Weight Chaff. Bushels per Weight etc. - Bushel lb. lb. cwt. (]. lb. 1 No manure ..... Comr^lete f Superphosphate 3 cwt. ) 42.5 49.9 54 28 3 18 2 44.7 48.9 65 26 3 0 [ Sul/Ammonia 1 cwt. ) 3 f Superphosphate 3 cwt. ) 45.0 47.1 66 31 2 10 1 Sulphate of Potash 1| cwt. ' / 4 f Superphosphate 3 cwt. \ ] Sulphate of Ammonia 1 cwt. " ) 41.8 48.4 62 29 0 4 5 J Sulphate of Pota>h l-l cwt. ) ( Sulphate of Ammonia 1 cwt. " j 39.9 49.1 50 29 0 8 The differences between the plots were but small, and, the un- manured produce itself reaching 42^ bushels per acre, showed that the land was a good deal richer than had been expected, and that it really needed no more manuring. 68 [b] Great Hill. Simultaneously with the foregoing, an experiment on an adjoining field of light sandy soil, but entirely on the Lower Greensand formation, was carried out. A light crop of swedes had been fed on this land by sheep, receiving also a little cotton cake. It was desired to see whether mineral superphosphate given in addition proved an advantage to the following barley crop. Two plots of |-acre were marked out, and to one of them super- phosphate at the rate of 3 cwt. per acre was given previous to the drilling of barley ("Plumage Archer") on April 25th. The crop was cut on September 16th, 1922, and threshed on January 24th, 1923. The results were : — Malting Barley Experiments (Great Hill) , 1922. Produce of Barley per acre, after Swedes fed off by Sheep. • Manures Head Corn Tail Corn Straw, Plot Bushels Weifjht per bushel Weight Chaff, etc. 1 2 With Superphosphate Without Superphosphate 34.6 38.4 lb. 51.5 51.1 lb. 99 69 cwt. q. lb, 16 3 15 17 1 11 On this lighter soil the crop was lower than on Warren Field, but was by no means a bad one for the land. The straw, however, was much shorter, and only about half the yield of Warren Field. The addition of superphosphate did not appear to have increased the yield either of corn or of straw. 7. Experiments with Potassic Fertilisers {Sulphate and Muriate) on Potatoes. In 1922, experiments were carried out at W^oburn, in common with other centres, for the purpose of testing the respective in- fluence of sulphate of potash and muriate of potash, on the yield, quality, etc., of potatoes. The field selected at Woburn was Lansome Field, and the variety "Kerr's Pink," the seed ha\ing been obtained direct from Perthshire. The soil is a light sandy loam, very suitable for the growth of potatoes. Spraying with Bouillie Bordelaise was carried out on September 1st and 2nd, and a second time on September 20th, though there was but little appearance of disease. It was noticed during growth that the plots treated with muriate of potash were lighter in colour than those with sulphate of potash, and also that the tops were bigger where no farmyard manure had been given. The lifting of the crop began on November 15th when the crops were weighed, and the returns are shown on page 69, In this table the weights are recorded as taken when the crop was lifted, whereas the separation into "ware," "seed," and "diseased" was not made until several months later when the potatoes were actually sold. Owing to difficulties in disposing of 69 K.\pcr'niie}its with Potassic Fertilisers on Potatoes (Lansome Field), 192^. Produce per acre. Plot. Manuring per acre. Kerr's Weight Pink, per acre Series A with Farmyard Manure 12 tons. T. c. q. 11.. 1 3 (Superphosphate 4 cwt. | ■ + li cwt. Sulph. Potash j- (Sulph. Ammonia l-i cwt. j 12 12 2 10 0 1 0 20 2 4 Superphosphate 4 cwt. | + equivalent in ;• Sulph. Ammonia 1^ cwt. Muriate of Potash) Series B without Farmyard Manure. 13 12 14 1 0 3 16 16 5 7 (Superphosphate 6 cwt. j + li cwt. Sulph. Potash (Sulph. Ammonia 2cwt. 13 13 8 8 2 1 12 24 6 8 Superphosphate 6 cwt. ) \ + equivalent in (Sulph. Ammonia 2 cwt. Muriate of Potash ) 13 13 13 19 0 1 12 12 the crop, the actual removal from the heaps and sale only began in the middle of March, 1922, and continued till the close of May. Hence a division of the crop into the three sections would give no fair comparison, as the shrinkage in weight owing to storage, sprouting, etc., would vary with the time of keeping. It may, however, be said that there was, on the average, no difference between sulphate of potash and muriate of potash either in respect of "seed" — which worked out at 7% — or of "diseased" — which did not exceed 1%. The duplicates, with the exception of plots 2 and 4, agreed very fairly. Muriate of potash gave, on the average, 10 cwt. per acre more yield than did the same amount of potash as sulphate. Also the yield was 1 ton per acre more where, in place of farmyard manure, additional superphosphate and sulphate of ammonia were used. The crop all round was a splendid one ; it gave but few diseased tubers, and, after being pitted, it kept well throughout the winter and right on to May, 1923. POT-CULTURE EXPERIMENTS, 1922. Though the transference to Cambridge of the work hitherto done at Woburn under the terms of the Hills' bequest, brought to an end my official connection with this, yet the experience I had derived during a period of 25 years, and the interest I felt in the methods of enquiry pursued, determined me to carry on the ex- periments so far as I found this possible. Similarly, the many enquiries that had been initiated and were still in progress in connection with the Woburn field experiments rendered it desirable that these, too, should be continued. This I have succeeded in doing, and the present is an account of the work carried on m 1921-22. 70 I. The Hills' Experiments. These — if I may be allowed still to apply the term to them — embraced in 1922 : — (i\) The action of (X)mpoiinds of Lead on wheat. (/)) The action of Chroiniiim (•()m|)()iincls on wheat. [a) Lhad Compounds. In previous work in li)12 (journal R.A.S.E., 1912, pp. 32-1-5) it was found that lead salts, when present to the extent of .03% of lead in the soil, exerted no harmful influence in the case of the phosphate, nitrate or <\'irbonate. In 191-1 (Journal R.A.S.E., 1914, pp. 312-3) the same salts, but in higher amount (up to .10% of lead), and with the sulphate and chloride additionally tried, similarly failed to show any injurious effect. The subject was then left for a time, but I returned to it now, taking- still higher amounts of the metal and using- the following compounds of lead, the oxide (litharge), carbonate, sulphate and chloride. The quan- tities now employed were respectively .25%, .50% and 1% of the metal. The salts were mixed with the whole of the soil in each pot, and each experiment was, as usual, in duplicate, the soil being that from Stackyard Field. Wheat was sown on December 20th, 1921, and nothing was noticeable with regard to germination except in the case of the lead chloride sets. In these .25% slightly retarded germination, .50% still more so, and 1% very markedly. The full number of plants did not come up in any of these. The only differences between the crops, and only signs of any toxic influence were with the chloride; with this, .25% did not appear to do any harm, but with .50% there were only one or tw^o weakly plants left, while with 1% the few plants that came up at first died away entirely. Plate I. shows the appearances very clearly, and the compara- tive weights In the case of the chloride are given below. Lead Chloride upon Wheat, 1922. Treatment Corn Straw Untreated .... Lead Chloride Lead Chloride Lead Chloride .25% Lead .50% Lead 1% Lead 100 136.3 100 116.1 From this experiment it would result that lead present as chloride in a soil will produce a toxic effect as soon as the quantity exceeds .25% of lead, but that in the forms of the oxide, carbonate and sulphate, no harmful influence is exercised up to 1% of lead. (b) Chromium Compounds on Whkat. 1. — The experiments of 1920 and 1921 with chromate and bi- chromate of potash were continued for a third year, the sanie pots without alteration or addition being used again for a third corn crop which was sown on October 27th, li)21. By way of recapitulation, it may be said that in the first year 71 0) C 0) u o r4 ^ 1^ §! ^ -^ ^ H ■ ^ (1) tt« X C 1) ^ ^ •a rt o 'A U ^ s! ^ U :d 'rt ^ m *"1 T} G c c4 D ?^) 2 g ^ ,_l o u 3 I Q 8 « 2-2 O f ) a e ti^.2^ c o 'en .-^'X . . o ^ C J- "^ u ^ 5 tuc B> - ^ 4) u o! TS O :c §^ ^E E •a P-2 ll'§ •a'Q 9 76 Fluoncles on Wheat, 1922. Treatment. Corn Straw Untreated Calcium fluoride 5 cwt. per acre . Potassium fluoride containing .1 percent. Fl. .05 Sodium fluoride ,. 1 ,, .05 Calcium-silico-fluoride 5 cwt. per acre 100 170.3 470 451 292 55.4 100 139.5 262 244 202 76 IV. The Influence of Silicates on Wheat, 1922 (3rd Year). The experiments of 1920 and 1921 were carried a further stag^e, no further additions being g-iven, but wheat being sown again in the pots on December 21st, 1921. The previous years had shown calcium silicate to give an increase in the crop as the amount of it was increased, and this up to an application of 4 tons per acre, the increase being more marked the second than the first year. On the other hand, kaolin produced no effect, and magnesium silicate a less marked one than calcium silicate. The 1922 results were of similar nature, showing a continued benefit from calcium silicate, increasing as more was used, while that of magnesium silicate was, on the whole, less. The three years' results follow : — Silicates upon Wheat, 1920-2. 1920 1921 1922 Treatment 1 Corn 1 Straw Corn Straw Corn Straw Untreated 100 100 100 100 100 100 Calcium silicate, 1 ton per acre 113.4 104.1 146 126 128 107 ,, ,, 2 tons ,, 124.4 116.8 187 136 150 117 ,, 4 150.1 139.0 226 159 197 140 Magnesium silicate, 1 ton per acre . 111.9 115.1 96 115 97 101 2 tons 109.5 124.5 149 135 168 110 4 113.5 135 4 172 139 179 123 Kaolin, 1 ton per acre 83.8 1 104.3 68.5 83 70 81.5 2 tons 96.5 100.3 ? 77.5 76 71 ,,4 103.0 96.8 108 98.5 98 102 From this it would appear to be clearly established that calcium silicate is a far from inactive form of lime, and that this may have a bearing upon the experiments recorded under II. in this section, as regards the relative efficiency of lime and chalk. 77 OS > H > < O o O di i • *J ^ X *j ji: • ^ x; m o ,. 89 see pp. 87 and 88 ^ On CM Yield per Acr J3 u en 3 J3 c« (fl tn 3 3 3 ^ ^ -^ CM VO c o 4) 0^ d, !>. 00 : ci CM O no C^ 2 ^ IT) —1 55 V> ^i. 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"!^JO l«JO ^ rO rH rH CM CM rH ^ CM CI rH r-H i-< r-* -H CM ' c 2 laqsng J3d jq^PM .00 O -"t- CO o tn 00 o «n ON CO 00 CO O O CO NO 00 ON ^- ro rH o CM NO O in Tf i — io u-> vO vO K CO -^ NO O t>» ro Tj- Tf vO in in in t^ '<^ m NO c^ vO 00 in -^ CM in o »0 IT) »0 »r> lO vn in >n m o lo m in »n lo w-} in in in in m in in m in in lo in t •9J0V jad J= VO ON O t^ CM — 1 .-< O CO t^ CN r^ CM CM t^ O 00 On CO rH O 'H o o CN m -*- -"t- a > 3 t^ t^ ro VC rw -^ t^ O O CM t> CO 00 PO ro CO rH 00 ro O NO 00 ,_, 00 t^ 00 00 rH Q PP!A rH CM r^ CO CM CO CO rH ro rH CM CM ro r-. ^ '-' CM CM ■'- : : : : OJ • • • • rt only nd Amm. Salts mm. Salts s and Amm. Salts d Amm. Salts ... oda of Soda Nitrate of te of Soda pe Cake ake Rape Cake o CM ' 03 : c . 1- 3 ■ X 0, B: c a; a <*- rt c ^ O _V-; rt 03 00 - - - nd Ra ape C sand 6fi C : 5 0) S o 3 hate o only ineral Super Salts hate a and A ineral er. an oda o Nitrat and^ [ineral 'O c^K-^ o • 2 rt IS c rt e only sphate ts and Miner ^ 3 C i3 rt y. 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C-^ b CM w f>- 0 -(- — Oi X 00 b ^ CM CM b C- J eg CM CM CM 00 « vo ro 00 b^ rf b t^ on to CM ro CM O rH CM CM CM CM On CN ON ON O --^ CM ON r-i CM CM CM ^ On On On On On O ^ CM ON CM CM CM .-H On On On ON O -H CM ON CM CM I CM r-i On On I On On O — CM On CM CM CM ^ On On On On C/) a, '3 m 0) O cd 5 o i-H CM ro -^ in -G : '. ; 0) : &, C/) zi s ^ J3 "So a aj3 C ctJ '0 • - 7) 0 rt Q 0 0 sS n a, c 0 c 0 B-o U 0 ^ U U C/5 3 : en ^ CM po -^ in CM CO -^ in ?5 : 'cS •^ ri O ^ ri c '^ o c '^ .-I CM en -^ in nj- ^ c/^ 0 0 en a. CM en ■<*- in W e) :5i? i o ^ 3 c • 4J 1_ *^ . *^ 0 m p 3 1_ IT- -Ti wiQ-: 4) . c a. <2 S-2 3^ 2 = rt = 1 « 2 c c^^ s^ |.uE<< >, 92 STRAW EXPERIMENT, 1921. Potatoes (Arran Chief). Sawpit Field. Manure per Acre. Yield per Acre. 1st 1 2nd 3rd Plot Plot Plot Tons 1 Tons Tons 1 8 tons Rotted Straw Manure — Single Nitrogen 230 2-18 1-96 16 , 2-48 2 63 216 32 173 239 229 ! 2 cwt. Sulphate of Ammonia 120 1-48 113 4 ,, ,. ,, 166 1-57 1-48 8 .. .. 1-52 1-71 1-38 16 .. ,. .. 1-41 1-55 127 8 tons Rotted Straw Manure— Double Nitrogen ... 209 1 2-20 186 16 ,, 332 > 259 250 32 , 216 ' 2-68 204 Control^No Manure 139 161 141 1'52 1-45 139 Single Nitrogen represents 1 cwt. Sulphate of Ammonia added to 1 ton of straw. Double Nitrogen represents 2 cwt. Sulphate of Ammonia added to 1 ton of straw. RESIDUAL VALUE OF SLUDGE, 1921. Long Hoos Field. Treatment of Plots in 1920. Manure per Acre. Dressed Grain. Yield per Acre. Bush. Weight per Bushel. lb. Offal Grain per Acre. lb. Straw per Acre. Total Straw. Straw, lb. cwt. 1st 2nd 1st 2nd 1st 2nd ! 1st 2nd 1st 2nd Plot. Plot. Plot. Plot. Plot. Plot, i Plot. Plot. Plot. Plot. Proportion of Total Grain to 100 of Total Straw. 1st 2nd Plot. Plot. 1921, Wheat (Red Standard) after Potatoes (1920).'= Activated Sewage Sludge, 13 3 tons Farmyard Dung 15 tons Control 29-8 127-9 348 260 [316 269 640 640 63 3 641 641 630 371 296 342 406 371 325 2925 2461 2299 2624 2600 1997 327 303 262 308 622 636 29-7 266 745 67 6 720 677 1921, Wheat (Red Standard) after Barley (1920).t Sulph. of Ammonia 145 cwt. Activated Sewage Sludge, 27 tons Control ... Control 24-1 30- 1 272 27-4 630 630 62- 5 r.3 0 387 351 405 435 2738 2857 2738 2333 311 314 294 303 546 641 63 9 637 * In 1920 this set received a basal dressing of 6 cwt. Super, and 1 cwt. Nitrate of Ammonia per acre. No manure was given in 1921. 1 In 1921 this set was manured as farm, viz., 1 cwt. Sulphate of Ammonia and 1 cwt. Superphosphate per acre. 93 rain of raw s*" ::Ogt^ _o ^j \' nj "" •« Pu -^oBo _^_ -H h O^ CU o-^ 0. is (n% o^. — t) 0. o V < H 2 1- % ^ rtji ^^' 0, C/5 ^ J2-* ;u ■« Si §^ ^1 o ^ ro ■^ Q r^ <0 lO vO o vO CM oa cv Tf- •^ o t^ 'b fo ■^ r^ r<^ CO O O O O Tf cvj 00 O «0 VO f CN CS OJ CM o O 00 CTv t^ 1- Tj- in -^ o o m o (N 00 CO « ■^ en •<*- -^ •^ vO CO VC t^ ro r^ 00 m Tj- lo -"f CM »n 00 i^ m •^ Tj- rf : ex ci. ^ i? ^ O O O 45 '-'-''-' C . • . rt U >-■ Ui 1^ o oj (u 2 a a a ^ :3 s D o O) c/5 c/5 Jz; II I I I I I S I o § CO I I I I i-i isi a>vO t^ OOOOivOvO.CM— ivO T^ vo f>o o VO t^ II I I I I I i II 1 1 CM CM o o VO O ooooo ooo O 00 o o -^ ■ ' ' C^ On 00 C\ t-^ ooo •O vO 00 ro O O CM CM CM II I I II i§ I IS I o m \n o vO ^ O >0 «0 »0 lO t^ ^ 00 00 O m ■^ CO -^ -^ I 00 VO ' CO lo oioooooioioin Ci potooocnvot^-^ T^ •^PO«nw-)rr)COPO-^ I 1 1 1 I3I I5.I 10 o o o in o CM CM CM CM CM CM vO vO vO vO O vO 0>0c0>00i0>0»r> CMCMCMCMCMCMcnCM | vO vOvOvOvOvOvOvOvO II I I I I isi li 00 t>. 0^ r-i Tt- CM en in vo VO t^ 00 VO CM VO r>. CM vo OOVOO■»^«OO^CM>0^0 (OvOt^vOvOiOTjvOvOvO Ov vO Qv O t^ '-^ O 0^^-t^00r-lCM0^O■>*-v0 ^^^^CMCM^CM^^ CM 0 ^ 00 00 CM CO 0 ■'4- in C^ rn -H f-H r. 00 CM CM CM CM CM rH ,-H OCM'-i-CMOiO-^CMCNIvO t^cM^ooin-Hino t^incncnt^t^cnc* | en m ^7 CM CM ^ rt rt ctJ a, 9- ex. " " CM eO J3 <>' OCMt^CMCMin vO'^'^cooot^-'j-incMfn oooinooinininin in in 'n t^ iri in c-^ t^ (vj rv^ vooct^oovoc\t^vomin inoinooooooin cM>n<^iinooooinc^i rrr^voint^oot^t^CMcn 88 C^J CM •>4-fn'n CM in -^ >n in o en in I I I II I I in in o o u 00 CO 'I- '- O ..-H 00 C^ 00 ro ^ ■^ i-i PO ^O O -4 rh On -^ O . -^ T^ l^ O 00 £ On O *0 vO '^ Series B ^^ t^ O fO rn S vo fo m 00 00 en ^«n »n vo vo ^ ^b 00 00 t^ VD r^ o t^ IN fn O t^ O O O I in Tj- lo lo lo I ro fO f^ fO ^ I ' S — I On O ■<<- j CM r0 00 ro O 00 OO O io t^ rO ^ O CO O O r-l CM r-H in o m -H W>;^ 1-H r-H I— 1 >— 1 in u-) 00 in t^ t^ ro r^ on on . in in CM o J>- in Tj- >. r^ 1 '^■' 00 rn I o I--. o ^ CM 1 ^ 00 00 on l^ 00 ^ .—1 1— ( rt rt a . . . rr cr • c • • • M-l r; "n rt^ 0. rt • . • - 1>- ar be 00 rt a «2 >> C/) 00 S> ^ -s . rt . . o . tyO ajc-G be : i2£ : 3 C c a •— if) 3 O .5 c 1 Is ^ ^?^ ^:2SS '^ rt rt 73^ rtS a S^ ^- ^ o m CQ m m;25 97 Slag Experiments— cow^J. Swedes (Hurst's Monarch) Produce per Acre. Great Harpenden Field, 1922. Manuring pei Acre. • Roots. Leaves. Slag Slag i Slag Slag Slag Slag 1 No. 20. No. 2. j No. 1. No. 20. No. 2. No. 1. j Tons. Tons. : Tons. Tons. ' Tons. Tons. Sulphate Ammonia 2 cwt., Sulphate Potash 1 cwt., Slag full quantity ... 25-92 2792 3040 4-89 3-82 416 Sulphate Ammonia 2 cwt., Sulphate Potash 1 cwt.. Slag full quantity ... 3208 3031 30-40 401 504 4-20 Sulphate Ammonia 2 cwt., Sulphate Potash 1 cwt., Slag half quantity. 1 Gafsa Phosphate. 175 lb 2719 2804 31-88 ' 4-18 3-53 4 10 Sulphate Ammonia 2 cwt., Sulphate Potash 1 cwt.. Slag half quantity, 1 Gafsa Phosphate. 175 lb 2821 2978 28-82 4-28 416 427 Sulphate Ammonia 2 cwt., Sulphate i 1 1 ' Potash 1 cwt., No. 7 Nauru Phos- phate, 262J lb 3096 2643 2650 1 4-49 4 00 3-98 Sulphate Ammonia 2 cwt.. Sulphate Potash 1 cwt.. No. 3 Gafsa Phos- phate, 350 lb. 27 83 3112 28-46 395 4-58 4-66 Sulphate Ammonia 2 cwt.. Sulphate Potash 1 cwt. 2721 31-45 25 -74 416 5 02 399 No Manure 25 67 27-23 22-70 3-54 3-67 319 Note.— "Full Quantity" Slag is No. 20, 1275 lb. per Acre. No. 2. 1225 ,. No. 1. 875 .. Description of Slags Used. No. T,„,^ Total Phosphate' ^^^' asCa3(P04).2 1 1 Solubility % 1 Open Hearth, L.G., H.S 1 ! . ! 250 : 904 2 L G.. L.S. 180 357 8 Phosphate, Slag Mixture 531 25-5 12 Talbot Process, H.G., H.S. 37-3 1 80-7 13 Open Hearth, L.G., H.S. 22-7 ! 91-5 14 L.G., L.S. . 22-6 ' 290 15 Talbot Process, H.G., H.S. . 400 72-5 16 Open Hearth, L.G., H.S. . 21-3 883 17 Bessemer, H.G., H.S. . i 42-5 772 18 Open Hearth, L.G., H.S. 20-8 670 19 L.G.. L.S. 20-2 210 20 L.G.. H.S. 17-2 78-8 L.G. = Low Grade. L.S. = Low Soluble. H.G. = High Grade. H.S.=H igh Soluble. 98 POTASH EXPERIMENTS. Dry Matter per Acre. Yield per acre. Manuring per Acre. 1st 2nd 3rd Plot , Plot Plot 1st i 2nd Plot Plot 3rd Plot Clover. West Barn Field, 1922. Control Sulphate of Potash, 210 lb. Cement Works' Dust, 511 lb lb. 1369 1533 1381 lb. 1273 1929 1710 lb. 1507 2123 1729 cwt. 152 186 175 cwt. 157 250 218 cwt. 186 264 21-4 Potatoes (Arran Chief). Sawpit Field, 1921. With Dung. 12 tons per Acre. 3 cwt. Super 3 cwt. Super 3 cwt. Super 3 cwt. Super 1^ cwt. Sulphate Ammonia, 470 lb. Sylvenite IJ cwt. Sulphate Ammonia, 1^ cwt. Sulphate Ammonia, Ih, cwt. Sulphate Potash 1^ cwt. Sulphate Ammonia, 1| cwt. Sulphate Potash, 95 lb. Sulphate Magnesium ... No Manure. Control 3 cwt. Super., 1^ cwt. Sul. Amm., 1^ cwt. Muriate Potash ... 3 cwt. Super., 1^ cwt. Sul. Amm., l^cwt. Muriate Potash, 84 lb. Sul Magnesium Without Dung. Tons. 3-57 3-55 I 3-67 *307 *2-28 *2-31 *2-43 Tons. *315 *3-18 4-27 392 348 4-24 Tons. 3 71 372 388 387 318 397 2 cwt. 2 cwt 4 cwt. Super., 2 cwt. Sul. Amm., 625 lb. Sylvenite 4 cwt. Super., 2 cwt. Sul. Amm. ... 4 cwt. Super., 2 cwt. Sul. Amm., 4 cwt. Super., 2 cwt. Sul. Amm. No Manure. Control 4 cwt. Super., 2 cwt. Sul. Amm., 4 cwt. Super., 2 cwt. Sul. Amm., Magnesium Sul. Potash ... Sul. Pot., 127 lb. Sul. Mag 2 cwt. Muriate Potash 2 cwt. Muriate Potash. Ill lb. Sul 3-19 404 143 1-48 348 4-28 385 426 1-24 172 . 415 4-20 '. 427 3-93 311 115 352 325 165 400 3 63 390 , 415 I Potatoes (Arran Chief). Sawpit Field, 1921 4 cwt. Super., 2 cwt. Sulphate Ammonia, 232 lb. Sul. Potash 4 cwt. Super., 2 cwt. Sulphate Ammonia 4 cwt. Super., 2 cwt. Sulphate Ammonia, 54 cwt. Sylvenite Control. No Manure. 300 I 246 I 2-82 116 ! 098 I 089 '1 93 336 I 304 '073 1 10 ' ri6 Potatoes (Kerr's Pink). Great Harpenden Field, 1922. With Dung 15 tons per Acre. j Basal Manuring ( = Super. 4 cwt., Sul. Amm. 15 cwt per Acre) ... 8'78 I 7"72 ; Sulphate Potash 183 lb. + Basal Manuring ... ... ... ... { 949 I 972 j Muriate Potash 148 lb. + Basal Manuring ... ... ... ... j 9 22 960 I Muriate Potash 148 lb. + Salt 497 lb. + Basal Manuring 984 I 9'49 7-60 945 882 914 Without Dung. Basal ( = Super. 6 cwt.. Sulphate Ammonia 2 cwt. per Acre) Sulphate Potash 244 lb. 4- Basal Muriate Potash 197 lb. + Basal Muriate Potash 197 lb. + Salt 662 lb. + Basal Muriate Potash 197 lb. Sulphate Magnesium, 344 lb. Muriate Potash 197 lb. Salt 662 lb. + Basal ... No Manure Sulphate Potash 244 lb. Sulphate Magnesium 344 lb. Cement Works' Dust 614 lb. 4- Basal Svlvenite 541 lb. + Basal + Basal + Basal 211 2-75 257 788 896 806 862 873 762 845 8-27 843 8 68 890 7 62 866 802 751 3-23 287 283 925 8/9 711 7-47 6 66 638 838 7-92 6 90 Produce per Acre. * On these plots the bouts were badly broken down due to extra hoeing on account of the growth of Wheatbind. Mangolds (Prizewinner Yellow Globe). Great Harpenden Field, 1922. Manuring per Acre. Roots. !J Leaves. j 1st Plot Tons. 2nd Plot Tons. 1st Plot Tons. 2nd Plot Tons. No. 9 Slag 4 cwt., bulphaie Ammonia 2 cwt., Sul- phate Potash 2 cwt No. 9 Slag 4 cwt., Sulphate Ammonia 2 cwt No. 9 Slag 4 cwt.. Sulphate Ammonia 2 cwt., Cement Works' Dust No Manure 1764 1045 1875 10 14 12 11-61 1825 88 ! 5-57 473 513 4-94 596 25 99 POTATOES. Relative Effects of Sulphates and Chlorides on different varieties. Great Harpenden Field, 1922. Variety. Dunged Series. Undunged Series. Actual Weight of Potatoes. Average Weight per Plant. Actual Weight of Potatoes. Average Weight per Plant. Is u mx 1^ IS II ii (/3 Ji u 1 IS lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. lb. Ajax ■ 16 24 27 121 21^ 16J 191 33 320 400 386 2-55 3 04 413 2-82 175 471 13i Mi 7i 171 18 23 4 4i 4 2-25 246 242 254 3 00 329 100 0 64 0 67 Arran Comrade \ m m 111 101 m 13 13 225 256 258 196 215 210 242 2 17 217 \\\ \\\ 15 81 Hi 18 3i li 1$ 225 188 2 14 146 225 257 065 030 029 British Queen j 261 19 181 25 19i ^^1 321 2-82 3-82 2-71 268 4-17 275 275 332 11$ 131 Hi 15$ 71 3l 146 236 196 196 192 263 111 118 075 Duke of York ...| 71 81 13^ 11 14 lOi Hi 14 HI 1 11 125 225 157 2 00 175 1-61 2 00 246 9 9i 6i 8 6i lOi 1 2i li 180 154 104 1-60 0-93 1-46 033 063 042 Epicure 16 14S 13i 18^ 10 13i 19i 236 1 64 229 211 193 264 1-43 225 2 79 121 13^ 111 9$ 13$ 12.i 1$ 3$ 204 1-93 168 163 196 179 035 054 025 Great Scott ..J 13^ 2l| 27i 19i 245 29 2U 19* 24| 338 307 389 2-79 354 414 307 325 350 2\\ 11$ Hi 13i % 1 307 196 238 2-46 213 265 075 0-42 050 Iron Duke ... - ( 24 21- 233 20 18^ 23i 21 16i 23 3-43 3 00 3 96 333 3 08 3-32 350 232 329 161 10$ 20 19i 20i 13 4$ 4 4i 279 179 286 275 289 325 068 1 00 064 K. ofK. ...-j 26 28^ 29i 231 27$ 20i 21 30i 371 407 421 3-39 463 4-21 289 420 4-32 2\\ 19i 18^ iTi n 5$ 307 275 3 08 310 104 082 1 Kerr's Pink ...- 25 261 20f 12 15 15i 3 04 357 382 296 318 432 2 00 3 00 388 181 24i 20$ 19i 22 6i 3i 5 2-68 192 3-46 296 390 314 093 0-46 071 Nithsdale ...| 18 15i 21^ 14i 20^ 26 302 20 14J 2-57 221 358 204 293 371 196 286 356 9 12 Hi 91 15 Hi 1* 2i 129 200 204 158 214 207 042 033 063 Tin Perfection - 20| 211 17 20| 121 231 23^ 3-46 311 250 283 296 321 2-55 339 336 20 18f 211 17 7i 8i 7 286 268 3 11 279 254 283 107 1 21 100 ( Up-to-Date ...- 251 20i 2n 231 25S 28| 251 25\ 281 429 293 425 339 368 407 421 364 411 261 20i 211 20i Hi 21 9i 8i 11 382 2-93 311 2-89 238 300 132 118 183 Note.— 7 Plants were set in each Row. Manures were: — Dunged Series: Basal Row: Super. 4 cwt.; Sulphate of Ammonia \\ cwt.; Dung 15 tons per Acre. Sulphate Row : Basal Manuring ; Sulphate of Potash 184 lb. per Acre. Chloride Row : Basal Manuring ; Muriate of Potash 147 lb. per Acre. Undunged Series: Basal Row: Super. 6 cwt.; Sulphate of Ammonia 2 cwt. per Acre. Sulphate Row : Basal Manuring ; Sulphate of Potash 244 lb. per Acre. Chloride Row : Basal Manuring ; Muriate of Potash 197 lb. per Acre. Potatoes. 100 Great Harpenden Field, 1922. Comparison of Varieties. < ma & 6 .a 0, W OJ o i a Q o i4 in . Q i D Average weight] of Potatoes [ lifted per rowj Average weight per plant ... lb. 1621 270 lb. 1054 1-90 lb. 1608 243 lb. 8-86 150 lb. 11-88 181 lb. 16-58 279 lb. 16-89 2-67 lb. 21-62 3-28 lb. 17-63 2-73 lb. 1349 223 lb. 17-49 2-62 lb. 21-47 317 Comparison of Manurial Treatment. Dunged Series. Undunged Series. Sulphate Row. Chloride Row. Basal Row. Sulphate Row. Chloride Row. Basal Row. Average weight] of Potatoes - lifted per row j Average weight ) per plant ...j lb. 2012 308 lb. 19-82 303 lb. 18-62 2-94 lb. 1517 2-36 lb. 1541 2-37 lb. 4-40 0-80 PROFESSOR BLACKMAN'S ELECTRO CULTURE EXPERIMENTS. Clover. Great Knott Field, 1921. Plots. Yield per Acre Electro-Culture Control cwt. 420 41-2 Cereal Crops. Plots. Dressed Grain, Yield per Acre. Bushels. Weight per Bush. lb. Offal Grain per Acre. lb. Straw per Acre. Straw. lb. Total Straw. Proportion of Total Grain to 100 of Total Straw. Oats (Grey Winter). Foster's Field, 1921. Electro-Culture Control I. ... Control II. ... 407 434 241 1543 193 33 1 420 298 1220 149 31-6 422 234 1102 146 930 101-4 960 Wheat (Red Standard). Foster's Field, 1922. Electro-Culture Control, North East Control, South East 15-4 61-4 234 1229 158 165 60-6 249 1272 15-5 17-2 61-8 231 1196 14-2 669 72-1 81-5 Barley (Plumage Archer). Great Knott Field, 1922. Electro-Culture Control 341 32-4 49- 1 486 273 244 1808 1840 22-2 22*3 78-2 72-8 101 BORON EXPERIMENT Barley (Plumage Archer). Little Hoos, 1922. Dressed Grain. Offal Grain per Acre. Straw per Acre. Proportion of Treatment •Yield per Acre. Weight per Bushel. | S."W. 1 sT?fJ. Total Grain to 100 of Total Straw. of Plots. Bushels. lb. ; lb. lb. cwt. 4> V V V 1 T Cn in in 2 u (u j= CM CM Cvl --^ O 0 t^ ,-1 in in in m CM ■<^ CM fn CM i-O •MBJJS IBJOX u-> rf Cv) o o '*• jo 001 OJ in in in On t^ in UIBJO IBJOX 00 .-H 00 O t^ 0 JO uopjodojj ,-1 r-l O U « o ? 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