l-h^-2 -HS^ Bulletin 458 May, 1942 Soil and Crop Interrelations of Various Nitrogenous Fertilizers Windsor Lysimeter Series B M. F. Morgan and H. G. M. Jacobson«-.kic GOVERNMENT PUBUIC^TVONS RECEIVED OCT 23 «79 ,,.»«^uNW£RSvrr uBRARt ^^^BSITV f CONHECTICU (Hixnxtttiitni ^^ticttlftttral ^xpettmcnt Station STATE Bulletin 458 May, 1942 Soil and Crop Interrelations of Various Nitrogenous Fertilizers Windsor Lysimeter Series B M. F. Morgan and H. G. M. Jacobson domucittnt CONTENTS PAGE Introduction . . • • • • 273 Plan of Investigation 275 Precipitation and Other Weather Conditions . 280 General Conditions Affecting Leaching 282 Nitrogen Availability in Relation to Crop Removal and Rate of Leaching 284 Cumulative Effects Upon the Nitrogen and Organic Matter Content of THE Soil 288 Residual Available Nitrogen After Ten Years of Treatment 290 Crop Removals and Drainage Water Losses of Several Constituents 291 Net Soil Gains or Losses 294 Soil Changes as Reflected by Chemical Soil Analyses 297 Exchangeable Bases 297 Total and Available Phosphorus . : 299 Total Potassium 301 Moisture Equivalent .....'. 301 Soil Changes as Related to Soil Acidity 301 Evaluating Acid or Basic Effects of Fertilizers 306 Acid-Base Balance in Tobacco Crops 311 Constituents Leached and Removed by Crop in Relation to Seasonal Dis- tribution OF Leaching 312 Conclusions 318 Summary 324 References 328 Lysimeters at Windsor Substation. Above, exterior view, taken in 1929. Below, interior view showing collecting chamber. Soil and Crop Interrelations of Various Nitrogenous Fertilizers Windsor Lysimeter Series B M. F. Morgan and H, G. M. Jacobson NITROGEN as a fertilizer may be supplied from a greater variety of sources than any of the other nutrient elements. Inorganic salts furnish nitrogen as the nitrate, in combination with various bases, or as the ammonium radical in salts of various acids. Synthetic organic chemicals supply nitrogen as carbamide (urea) and as cyanamid. Natural organic materials of many sorts contain a sufficiently high amount of readily decomposable proteins to be useful in fertilizers. These include: various oil seed meals, such as cottonseed meal, lin- seed meal and castor pomace ; packing house by-products, as tankage and dried blood ; fish scrap ; various animal manures. Only one class of the above materials, the nitrates, supplies nitro- gen in a form that is immediately and completely available to all plants. However, nitrates are susceptible to leaching from the mo- ment they are applied to the soil. The nitrogen in ammonia com- pounds is at least partly available to plants in the form it is used, and the ammonia radical is not readilj'^ leached from the soil. How- ever, ammonia is transformed in the soil to nitrates by biological nitrification, becoming more completely available as well as subject to losses by leaching. Urea and cyanamid quickly hydrolyze to am- monia when in contact with the soil and are subsequently nitrified. Proteins in natural organic materials are acted upon by organisms effecting their decay, to produce ammonia that may become changed to nitrates. The various materials also differ with respect to their interactions with the active constituents of the soil. Some increase the supply of soil bases, as in the case of the nitrate salts. Others produce depletion of bases through combined crop removal and leaching, thus increasing the acidity of the soil, as instanced by the ammonia compounds and most organic materials. Such changes indirectly affect crop growth, and often materially alter the chemical make-up of the soil. In spite of the above differences in the sources of nitrogen in fer- tilizers, it has become conmion practice in most cases to consider only the total amount of nitrogen supplied to the soil, irrespective of the form in which it is supplied. This view has appeared to be agron- omically sound as evidenced by numerous fertilizer trials with field crops since the yield differences between various nitrogenous fer- tilizers supplying equal amounts of nitrogen were of insignificant magnitude. Such results were possibly affected by numerous compen- 2T4 Connecticut Experinnent Station BuUetin 458 sating factors. The lime content and absorptive capacity of tlie soil could mask the acid effects of the treatment. Early leaching of ni- trates from soils supplied with nitrogen in this form tends to equalize the results with those from other materials giving slower and less complete liberation of available nitrogen. During recent years, the differential effect of nitrogenous fertili- zers with respect to the acidity of the soil have become generally rec- ognized. Meyer (13) in 1881, and Lawes Gilbert and Warrington (10) in 1882 were investigators who early pointed out such differences with respect to nitrate and ammonia salts. It began to receive consider- ation in this country with the work of Wheeler and Towar (21) in 1893. Later, other fertilizers were studied and various efforts were made to give a quantitative expression to the effects of nitrogenous fertilizers upon the base status of the soil, culminating in the scheme proposed by Pierre (16) for expressing the equivalent acidity and basicity of fertilizers. The literature in this field has been compre- hensively revised in an early publication by the senior author (14). The qualitative differences in fertilizer nitrogen have been most generally recognized where the value of the crop is largely dependent upon the quality of tlie marketed product, rather than upon the total yield. This has been especially true in the case of cigar leaf tobacco, as grown in the Connecticut Valley. The effects of various nitrogen- ous fertilizers upon the production and cjuality of such tobacco were studied to some extent in early experiments (1892-'96) at this Station by Jenkins (8) and have been constantly under investigation b}^ the Tobacco Substation since its establishment in 1922. Recent contribu- tions in this field are presented in Bulletin 444 of this Station, (3). Many studies relative to the amounts of nitrogen liberated to the crop from various fertilizer materials are extant in the literature. This Station gave early attention to the subject, conducting j)ot ex- periments such as those reported by Johnson, Jenkins and Britton (9). Those were followed by carefully conducted cylinder experiments un- der outdoor conditions at the New Jersey and Rhode Island Stations. The former were reported by Lipman and Blair (11) for the 1898- 1912 period, and by Lipman, Blair and Prince (12) for the 1913-27 period and, more recently, by Prince and others (18). Hartwell, Wheeler and Pember (7) summarized the early Rhode Island work. Many field fertilizer plots with various crops have been conducted in numerous states. Such trials have yielded valuable, practical agro- nomic information. However, they have failed to give a complete picture of the complex inter-relationships involved in rates and total amounts of nitrate production, crop intake at different stages of growth, losses through the leaching of soluble material from the soil by gravitational soil water after heavy rains and snow meltings, acidic and basic effects and other soil changes resulting from the continued use of a given fertilizer material. LTnder humid conditions, where gravitational water passes through the soil at frequent intervals, the losses of nitrogen and sev- Interrelations of Nitrogenous Fertilizers 275 eral other soil constituents may equal or exceed crop utilization. Hence, a fundamental study of the effects of fertilizer upon both the crop and the soil can be conducted to best advantage under lysimeter conditions, providing for the measurement and chemical analysis of the leachate as well as of the crop. Changes that occur in the soil as a result of treatment can thus be evaluated to the fullest extent. The present report deals with such a study of fifteen nitrogenous materials, applied to the soils in lysimeter tanks as components of complete fertilizers for tobacco, supplying nutrients in amounts such as commonly used for the crop in the Connecticut Valley. This ex- periment, designated as Windsor Lysimeter Series "B," begun in 1929, was conducted for ten years under differential nitrogen treat- ment and, for an additional year without nitrogen, to measure resi- dual effects. PLAN OF INVESTIGATION The physical equipment for conducting lysimeter experiments was described in detail in an earlier publication (14). The lysimeters are located at the Tobacco Substation at Windsor. The installation is as shown in the frontispiece, The tanks of Series "B" occupy the middle row on the courts surrounding the collecting chamber. These tanks are 20 inches in diameter and 20 inches in depth, exclusive of the tapering bottom filled with quartz sand. Successive fillings of mixed, carefully packed field soil, representing substratum (C) at 14% to 18-inch depths, subsoil (B) from 7 to 14%-inch depths and sur- face soil (A) at from 0 to 7-inch depths, were placed in the tanks. The soil surface in the tanks was approximately 2 inches below the rims, after settling for a few months. The soil used in this experiment is of the Merrimac sandy loam type, from a plot used for several years for tobacco, with oat cover crops. It was taken from the same location as the surface soil used in tanks 25 to 34 in Series "A," reported in Bulletins 384 and 429 of this Station. The amounts of soil used in the tanks, on the diVj weight basis, for the various depths, were as follows : Thickness Lbs. per Equivalent inches tank lbs. per acre Total 2 mm. soil soil Surface soil (A) 7. 116.05 2,321,000 2,300,000 Subsoil (B) 7.5 144.00 2,880,000 2,800,000 Substratum (C) 3.5 74.75 1,475,000 1,400,000 Pertinent physical and chemical measurements of the original soil, based on material passing a 2 millimeter screen, are given in Table 1. The fertilizer treatments were applied in dry form, mixed thor- oughly with the upper 2 or 3 inches of soil, on May 26 of each year 276 Connecticut Expenmcnt Station Bulletin 458 of the experiment, of the lysimeter. Each treatment was in duplicate on opposite sides Table 1. Physical and Chemical Characteristics of Soil Horizons Used in Lysimeter Series B, 1929-'40. Surface soil Subsoil Substratum A B C Mechanical Analysis (In percentages) Sand 74.2 76.5 78.6 Silt 19.0 18.9 18.6 Clay (.002 mm.) 6.8 4.6 1.8 Total water holding capacity 31.7 31.5 29.7 Moisture Equivalent 9.6 7.0 6.1 Organic matter 2.174 0.733 0.483 Nitrogen total .0620 .0225 .0130 Phosphorus total .1313 .0350 .0286 Potassium total 1.430 1.372 1.222 Calcium total .731 .936 .769 Magnesium total .311 .310 .268 Exchangeable bases (Mgm. — equivalents per 100 g ns.) Calcium 1.33 .55 .45 Magnesium .38 .36 .25 Potassium .43 .41 .28 Sodium .03 .03 .02 Manganese .02 . Exchangeable hydrogen 3.15 1.40 1.20 Base exchange capacity by summation 5.34 2.75 2.20 determined 5.20 2.70 1.70 average 5.27 2.72 1.95 Relative base saturation % 41.6 49.6 51.3 Soil reaction^pH 5.17 5.51 5.48 All tanks received phosphoric acid (P2O5) at the rate of 100 pomids, potash (K2O) at the rate of 200 pounds and magnesia (MgO) at the rate of 50 pounds (30 pounds for the first two years) per acre per year, except in cases where the quantities in the materials used to supply nitrogen were in excess of these amounts. These were added as precipitated bones, carbonate and sulfate of potash, carbonate of magnesia or as constituents of the nitrogenous material. Each of the nitrogen treatments supplied 200 pounds of nitrogen per acre annual- ly. No nitrogen was applied in 1939. One plant of "shade" tobacco (4 K strain) was set in each tank, soon after applying the fertilizer. Cultural practices in growing the crop closely approximated those for field-grown tobacco. Except in two seasons of unusually dry weather when small amounts of irriga- tion water were added, the crop was dependent upon natural rainfall. The tobacco plants, cut down to ground level at maturity, were dried, weighed and pulverized for subsequent chemical analysis. The tobacco crop of 1929 was completely cut to pieces by a severe Interrelatio'ns of Nitrogenous Fertilizers 27T hailstorm on August 31. It was impracticable to remove the frag- ments accurately, hence they were turned under by spading. At the conclusion of each period of leaching, the quantities of water that had drained into the collecting vessels were weighed and sampled. Nitrate nitrogen was determined as quickly as possible on each lot of leachate.^ Aliquot samples from successive periods of leaching were placed in glass bottles containing toluene (5 milliliters per gallon of leachate) to prevent further biologic action. The weighted composites thus obtained were analyzed for various soluble constituents by six-month periods, ending in May 25 and November 25 of each year. The total quantities of the various elements added to the tanks during the 11 years by the fertilizer treatments and by atmospheric precipitation are shown in Table 2. The amounts contributed hj atmospheric precipitation are com- puted from analyses of water collected in circular pans located in the east and west lysimeter courts. These pans are 20 inches in diameter, 4 inches deep, with funnel bottoms and underground drainage tubes leading to collecting vessels. These rain gauge tanks were installed in 1931. Results for the nine years were computed to 11 years. The materials used in these trials were lots purchased for use on the fertilizer plots conducted by the Tobacco Research Department at Windsor. The details of the chemical composition of various lots of each ingredient in the fertilizer mixture are omitted. However, the data in Table 2 are based on exact analyses conducted at this Station, chiefly by the Department of Analytical Chemistry.- The cow manure used from 1932 to 1938 represented fresh cow manure, obtained from a combination dairy-tobacco farm in the spring of 1934, air dried and stored in a tight container for use in subsequent years. Analyses for nitrogen, phosphoric acid and potash were obtained at the beginning. Unfortunately, calcium and mag- nesium were not determined on this manure until the close of the ex- periment. It was then discovered that the dry manure contained 4.8 percent of calcium and 0.83 percent of magnesium, indicating that limestone had been added to the manure. It was estimated that the extra calcium and magnesium content represented approximately 50 pounds of limestone in one ton of fresh manure. The farmer con- firmed this, having added some limestone in the gutters of his stable as an absorbent. The manure used during the first three years was fresh cow manure, of normal chemical analysis. The methods for analyses of leachates employed in this study are substantially as indicated in Bulletin 384 (14), published by this Station. 1 These nitrate measurements and other details of the work at Windsor were con- ducted by O. E. street, formerly Assistant Plant Physiologist at the Tobacco Sub- station. 2 The cooperation of Dr. E. M. Bailey, Station Chemist, has been of great assistance in the conduct of this experiment, through analyses of fertilizer materials and of the crops. 278 Connecticut Experiment Station Bulletin 458 Clh pq ^ S ^ s w o 2 fin a ou U '— ' ■* Tf- 00 f^ O "T^ 00 INI Ov GO 00 r^ o ■<* i^ r^ T(- '^ CM CO r^ if3 o .-i ^ fO CM CM CM io>JOioio>oioioiocoro>J^ uou-ju^i-Oi-Oi-OiOiOirj^vOiO cocococococococococococo lOlO 00 loio r^ CO CO 00 cot^cococococococococo^^O OOOOsOnOnOnOnOnONOnOnOn •— IIOt— Ir— 1<— (r- Hr— It— (t— li— It— II— I CO C0>-0 CO C3 ON ON t^ On '—I T— ll— (t-Ht— ItOT— ll-Ht— li— It— (r— iCO oooooooooooooooooooooi^ '^-*^^Oi*'"*"^^'^-*ON 1-1 O CO 00 ot^ ■^ r^ lo CMCMCMCMCMCMCMCMCMCMCMCM 0000000000(00 CMCMCnJCn)CMCMCMCMCn1CMCMCM CM CM - during April, or in May, in years when a wet May follows a wet April. Leaching during the fall months may be expected, except in un- usually dry seasons. In winter, water may drain from the soil during mild periods resulting in thaws. This has happened most often in January. Otherwise, the soil is frozen to a depth sufficient to prevent leaching during the cold months. March invariablj^ causes some drainage water to pass through the soil. On the average, leaching is at a maximum during the early spring period. However, as will be shown later, the losses of soluble constituents from the soil by leaching at this time are less than those caused by earlier leachings. The relationships betAveen rainfall, leaching and losses of mois- ture from the soil by evaporation and transpiration during various periods of the year are summarized in Table 4. Since the March leaching represents much water accumulating in or on the soil during the preceding months, it is included in the winter period. Table 4. Summary of Evaporation-Transpiration Losses by Seasonal Periods, Based on Average Data Windsor Lysimeter Series B, 1929-'40. Excess of precipitation over leaching Period Av. per day (inches) (inches) Winter months Dec, Jan., Feb., Mar. 7.09 .059 Spring months April, May 4.39 .072 Summer months June, July, August 10.06 .109 Fall months Sept., Oct., Nov. 6.09 .069 These data are in general agreement with those reported for Ly- simeter Series "A" in Bulletin 429. (15). However, the latter repre- sented surface soil only, under uncropped conditions. Data from Tanks 12.5-126, uncropped from 1932 to 1940, provide some basis for comparing evaporation losses with those resulting from both evaporation and transpiration under tobacco cropping during a portion of the year. The average yearly increase in leaching on the uncropped tanks for seven years, excluding the hurricane year 1938- '39, has been 1.62 inches. With an average dry weight production of 3,420 pounds of tobacco per acre for the seven years of the compari- son, this represents a water requirement of 1,075 pounds, per pound of dry weight, a fairly reasonable value under the conditions of this experiment. It should be borne in mind that the rims of the tanks prevented run-off that might otherwise occur during heavy rains and during periods of snow melting with frozen soil underneath. AVhen all of the precipitation must either evaporate or leach, drainage through 284 Connecticut Expervmerit Station Bulletin 458 the soil is somewhat greater than when some of the water flows over the soil to surface drainage outlets. However, the difference is prob- ably not great as compared with a level tobacco field of sandy soil, with a high infiltration rate. Even during periods of snow melting, there is little run-off under such conditions, although water accumu- lates in slight irregularities of the land surface, thus giving more than normal leaching after the ground thaws in such areas. For level land, such as the Merrimac sandy loam most commonly used for tobacco in the Connecticut Valley, the run-off may be con- servatively estimated at 10 percent of the total precipitation. Thus with a mean annual precipitation of 44.88 inches, under field condi- tions the leaching should be substantially the same as obtained under a precipitation averaging almost 10 percent less than normal, as in this experiment. There have been no consistent differences between the amounts of leaching on the various cropped tanks. The "no nitrogen" treat- ment, producing approximately one-half the dry weight of tobacco obtained from nitrogen treatments, leached 0.53 inch more on the aver- age (excluding the hurricane year). However, the variations from year to year and on replicate tanks prevented any statistically significant • interpretations. Leachings were slightly greater on the replicates on the west side of the collecting chamber, during the summer and fall seasons. How- ever, this was compensated by somewhat more leaching on the east side at other times. This is due to the sheltering effect caused by the projection of the walls of the collecting chamber above the level of the tops of the tanks, thus serving as a windbreak. Summer storms blow most frequently from the southwest while winter blizzards, as a rule, ride on a northeast wind, in this locality. NITROGEN AVAILABILITY FROM VARIOUS MATERIALS IN RELATION TO CROP REMOVAL AND RATE OF LEACHING Since the 1929 tobacco crop was not harvested on account of hail damage, and the 1939 crop was grown without nitrogen treatment as a measure of residual effects, complete data for crop and leaching in years of nitrogen treatment are available only for the nine-year pe- riod of May 26, 1930, to May 25, 1939, inclusive. The crops on the sulfate of ammonia treatments were generally poor, apparently due to the harmful effects of the excessive acidity resulting from this treatment. Crops on the cow manure treatment were unsatisfactory, due to insufficient available nitrogen from this treatment. The "no nitrogen" crop was small, as would be expected. Otherwise, it is questionable if the yield variations are of any signifi- cance. Occasional instances of poor plants, due to accident or injury, on one of the replicates, tended to cause yield variation. The average composition and yield of tobacco, based on separate analyses of the tobacco plant in each replicate for each of the nine Interrelations of Nitrogenous Fertilizers 285 years is shown in Table 5. Variations occurred from year to year. In some seasons yields were generally higher or lower than others, due chiefly to moisture conditions in the soil. However, the same general picture was shown throughout the experiment. These data will be considered in detail in subsequent discussions. The nitrogen removed by the crop was in most instances in close relationship to the total nitrogen recovery in both crop and leaching. Approximately one-half of the total available nitrogen was to be found in the ''above ground" portion of the crop as harvested. The low utilization in case of sulfate of ammonia is due to the harmful effect of the treatment. The amounts of available nitrogen from the nitrate materials were apparentl}^ too great for effective use. This is reflected in the higher percentages of nitrogen in the crop under such conditions. The data for nitrate leaching have been tabulated by seasonal pe- riods, so that the rate of leaching in relation to total nitrogen avail- ability may be indicated. Table 6 includes a break-down of nitrogen recovery to show crop removal, leaching nitrates by periods, and am- monia nitrogen leaching. Table S. Average Composition and Yield of Tobacco Windsor Lysimeter Series B, 1930-'39. Average Percent of dry weight dry weight Treatment of cropi K Na Ca Mg Mn N s P CI (Lbs. per A.) Nitrate of soda 2.74 .605 1.02 .399 .0059 2.78 .149 .228 .238 3255 Nitrate of potash 4.12 .168 .82 .375 .0070 2.54 .121 .180 .338 3626 Nitrate of lime 2.54 .067 1.69 .354 .0089 2.52 .157 .200 .258 3557 Sulfate of ammonia 2.61 .088 1.02 .368 .0746 3.11 .564 .272 .344 1969 Ammophos 2.24 .052 .85 .434 .0874 2.91 .317 .396 .322 2810 Urea 2.55 .071 1.25 .421 .0481 2.47 .179 .206 292 3415 Calurea 2.59 .058 1.39 .401 .0360 2.55 .181 .206 .296 3532 Cyanamid 2.65 .063 1.49 .270 .0092 2.47 .221 .185 .290 3327 Cottonseed meal 2.44 .061 .92 .452 .0352 2.10 .204 .187 .262 3543 Castor pomace 2.36 .061 1.07 .375 .0397 2.13 .175 .181 .356 3385 Linseed meal 2.44 .065 1.02 .399 .0378 2.12 .199 .194 .276 3471 Fish meal 2.29 .063 1.27 .352 .0342 2.06 .202 .206 .372 3827 Dried blood 2.25 .065 1.07 .374 .0625 2.11 .184 .159 .398 3653 Tankage 2.41 .067 1.26 .366 ,0312 2.08 .191 .209 .393 3983 Manure 2.16 .065 1.00 .392 .0047 1.43 .203 .226 .396 3314 No nitrogen 2.23 .077 .81 .307 .0076 1.17 .306 .259 .355 1602 1 Including stalks. Nitrate leachings were greatest from the nitrate materials during the growing season, as would be expected. However, under the condi- tions of this experiment, there still remained a sufficient amount of available nitrogen in the root zone to supply the crop with more nitro- gen than was obtainable from any of the other treatments except in 1938. In that season the severe leaching of the soil depleted the available nitrogen from the soils of all tanks to such a marked de- gree that there was no opportunity to differentiate between the vai'i- 286 Connecticut Experiment Station Bulletin 458 a S U o P^pq u o nS O tn a; - < c- OOOroOCJo'OOOOOOOOO rO'-HCvl^OOu^O'-HioCMroON'*'*!-^'— I cvi>-o-rt-r^'-it-^ONro^o6t-v!\dotviroc^i r^Oi— lO-Oj^O MDuTrfONrMCVlvOOCSI '— ii— lOs-^t^O'* VDOOOOi— iCM-^t^OO^O u-j ,-1 \q c^a 00 ^_ i-H c. O oj On --H r-t' ^' O cxi •^' Cvi ro 00 rv! Cvj l>! 00 CNOoo'vooooooNcot^r^j^t^r^oo^t— I nJ <^ rt ^ "^ •^ en H ;z; g ^^ O P^ P. 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CO CO ko On r-H 0 CM 0 PO ^r-l CM VO ro CTi "-"-I CO ^ 0 Ti^ \0 ro 0 T-H T-H CO \0 *0 CO r-( r-( CO ■^ ^ '=*! On t^ (O i-< O t-; --< -^ ui vq ro CTi ■TO NO o! 10 CM t^ ON On 00 c^i t< en ^ 10 o -- in 10 vo vq ON vo uS NO N CM t^ O^ CM !->. cj, ON NO iri 10 VD NO NO CO ^ t< CO NO IN. CO (-0 NO O fO ON N NO ■'I-" 1-! . ; , , , CVI CO I CN] CO I ^ ^ CO 00 CM CJ NO VO ■^ CM VO 00 r- < o, O CM cj O CM pg CMPOio t^'Thi-t NO-^o Nqr>.co ■^'-;io cn] CO ^ 10 CM 06 r^ c\i o c\i CM ui on cm ^ Tt CM vq '^ t^ <^ ON pq 10 NO i-H ro On CO O 00 O^ '— ' t^ Ol c?' ^' CO r^l t< u^ '^ Cvi VO 00 NO '^i^ t> 1— < o^' _ . . - . I^ t^ in '^ ,„ OCOO^ OnOOqo t-h 00 cj, 1-H ^ — ' 1-H On On CTi On t^ kO r-Jt-s. 00 On CO CM 00 o 00 '-; tv; 00 On NO 10 O CM (NJ I— I .—I CO CM .-H CO cviooo couooo i^r^*^ coNq^ ooooq '-;Ono o-; VO o CM CN] I^ O t>; >— < ro 'd- O to 10 00 CO i-l T-< O ^ On CO pg U jcj-5 — -H c o P-I JUo JUo hJUo u hJ -d 0 03 0 oj Ul rt fe Q H o U JU o 294 Connecticut Exferiment Station Bulletin 458 tent in the crop, conspicuously in the cases of nitrate of potash, fish meal, dried blood, tankage and manure. Manganese was present in the leaching in determinable amount only in the case of sulfate of ammonia and ammophos, the two most acid-producing materials. Manganese was present in the crop in general agreement with the effect of the fertilizer upon soil acidity, as will be discussed later. It is likely that some manganese dissolved in the soil solution in the surface soil layer was moved downward by leaching into the subsoil but, except as noted above, was retained in the lower soil layers. Sulfur, supplied in large amounts by sulfate of ammonia and in considerable quantity by ammophos, was most leached from the soil under these treatments. However, the crop showed no great increase in intake when the sulfur was thus supplied. Leaching losses greatly exceeded crop removals. Chlorine was readily taken up by the crop in general to a smaller relative extent when the nitrate supply in the soil was most abund- ant. Leaching losses were of similar magnitude to crop assimila- tions. Chlorides, present in various treatments as impurities and supplied to some extent by rainfall, were quantitatively recovered in the crop and leaching. Phosphorus did not leach. Amounts removed by the crop were in relation to the amount of growth, except in the case of ammophos, supplying over six times as much phosphorus to the soil as most other treatments. The crop obtained nearly twice as much phosphorus. The additional phosphorus supplied by tankage was slightly reflected in the crop intake. Inter-relations between various constituents assimilated by the crop and liberated from the soil to the drainage water will be dis- cussed in a later section of this bulletin. Net Soil Gains or Losses of Various Constituents The amounts applied in the treatments and brought into the soil by atmospheric precipitation .(see Table 2) may be compared with the total quantities removed by crop and drainage water during the 11 years of the experiment. The latter are summarized in Table 12. The computed net gains or losses, obtained by comparing the data in Table 12 with that of Table 2, are shown in Table 13. Calcium was removed from the soil in greater amounts than ap- plied, in most cases. The acid-reacting materials produced the great- est net loss. Manure, cyanamid and nitrate of lime, supplying large amounts of calcium, caused net gains. (It must be considered that the manure used in this experiment contained limestone.) It seems likely that fish meal supplied more calcium than had been computed from its composition. The net gain from the "no nitrogen" treatment is apparently associated with the smaller amounts of nitrates avail- Interrelations of Nitrogenous Fertilizers 295 6 o K « o; '^ W U. w w -l.-HrtT-lCMCMCM'-l i-ocMt^t^ONa\oooooooi-ovo(Nioo coooioot^t^r^t^cocooot^ONOovo^M iot^P0r^CMMDCMC0VOCVI<^rMir300MDi— I lOi— iCMi— (VO'^iOfOVOfOU-jCM^u-jvOOO CMrorO"^"^fO^CMcOCOro^f^rofOr-i vrSO'— 'lOCNi— it^0NCMt->.0\Oi— iiOTfu-i OMN-OST-iO^O^OO-^-rJ-^OOOcoCMVO 00.— I'^O^Oi-OOOt^CMTl-fO^O'^VOCVIt^ .-lCMCMT-<.-l'-HT-lr-(.-l.-H,-(,-l,-l.-( a! Tl (U a! rt rt rrt )-. ;-. 1-. .t; .■t^ ."t! 1 o W Q. O^Hr-iroON^^'— iC ^ u-j "* On CM tJ- 1—1 'O ,— 1 ►5 E-' -a D en 1 II o >H <; ?* O E +1 ++1++ ++I 1 + + C! O ^ OcoCMOnOsOMOOiO'^coijOO'— lOt^ w ;? '^^ o t^r-lV-lCMi— c'-i'— 1 C<1 >— 1 B w aj i/i "—I en S;; 1-1 J w oj S g a en »5 en HT3 E +++I ++++++++++++ -^ k^ 3 (^ ONTj-t-^r/^iou-j-Nt-'O^'^-^^aNasaNvo O ra vOTj-OoO'^'^^ON^iOiOT)-CM^t>»"* O D- lO O "* T-H T-l T-l .— 1 ,— 1 ^ >o -^W^ ^H-- J H E P.O D +++1 1 +++ ! I +++I++ O t/} C OOOCMrgt^ONroojT-Hi-c-irOOi-oCM^ £-c DO OrOCO^iO CM'i— 1<-0"*<^^^ T— (t^ + 1 OJ T-l ^ ^ lO ,-H 2 ^-^ p H r/i r' ifx ^ :z; tn ^ 15 < o Ou E + I+M 1 +1- M+M++ a 2 ■— >-00\<-OTl-T-HO^O^J(N)0-OCOtNlONCNlt^, O rt .S .2 1- n! O O Interrelations of Nitrogenous Fertilizers 297 able for conibinin<2; with this base. In case of nitrate of soda, the ni- trates were leached largely in combination with sodium, thus permit- ting a slight gain. Magnesium was generally removed from the soil in quantities similar to amounts entering the soil. The only substantial deple- tions were caused by ammophos and sulfate of annnonia. In most cases the net gains or losses were of insignificant magnitude. The large net gain in case of cow manure was presumably related to its contamination with limestone. Potassium showed net gains in all cases, except for the sulfate of ammonia treatment. As expected, tlie largest net gain was from the nitrate of potash treatment. Sodium in nitrate of soda appeared to produce a slight accumu- lation in the soil. However, this was insignincant in relation to the total application. In other cases the removal by leaching and crop was in close agreement with the amount brought to the soil by at- mospheric precipitation and in the treatments. Sulfur, applied in large quantities in sulfate of ammonia, and in ammophos, showed net gains. They were relatively small in propor- tion to the amounts applied. In other cases, the removal from the soil was similar to the amounts in the treatments and in the rainfall. Chlorine was removed from the soil by leaching and crop in al- most identical amounts to those supplied by atmospheric precipitation and as impurities in the various treatments. The small discrepan- cies are no greater than would be expected from errors in chemical analysis. SOIL CHANGES RESULTING FROM NITROGENOUS FERTILIZERS AS REFLECTED BY SOIL ANALYSES Exchangeable Bases The most important feature of soil changes produced by nitro- genous fertilizers is with respect to their content of readily replace- able (exchangeable) bases. This is directly related to soil acidity, since depletion of soil bases lowers the degree of base saturation, thus increasing the acidity through an increase in exchangeable hydrogen. Measurements of bases replaced by ammonium acetate solution (nor- mal) for each of the three soil layers have been computed to pounds per acre, on the basis of the acre weight of the fine soil (2 millimeters) in each layer. Separate data for each layer is presented on a different basis in a later section (See Tables 18. 19 and 20). The totals for the entire soil profile are shown in Table 14. These are also compared with the data for the soil as placed in the Ivsimeters in 1929. A cal- culation of the combined net changes in the four bases, on the basis of calcium carbonate equivalent, is included. The latter indicates the amount of limestone that would be required to compensate for the loss, or that is replaced in overcoming soil acidit}^ by the net gain. 298 Con7iecticut Ex'peiinient Station Bulletin 458 u X W . O xn U5 < W C ^ H rt W S (L> CO «^ H Q O < ., S en M W .'*Ot^coN ( T— I CM .— I r-( I— ( + + + ^t^O\-*roror^\OCMOgoOioiOTl-OCO 1— iu-)ooot^oooo\(NjaNONOOONOco^ fOCMi— (loroCMr-i.— (COfOC<10OCi^ '-' H U^ 03+j en rHrn-— ^ o3 >> O 03 .S .2 J:H fH bo m O ^ _ ^ „ _ on Interrelations of Nitrogenous Fertilizers 299 Net gains or losses of exchangeable calcium generally follow the same trends as indicated in Table 13. However the change is usually of less magnitude. In two cases, fish meal and no nitrogen, the soil analyses showed losses in calcium, although the lysimeter data in- dicated gains in this constituent. Magnesium changes are of similar magnitude and trends for both computations. In three instances, nitrate of lime, cyanamid and cot- tonseed meal, there is a slight dift'erence in the trend. Potassium, applied to the soil in greater amounts than leached or removed by croppmg, except in one instance, was not recovered from the soil by the ''base exchange" measurement in corresponding amounts. On the average, approximately 450 pounds of the potas- sium applied during the 11 years aj)pear to have been fixed in the soil in non-exchangeable form. This is in agreement with previous find- ings in Lysimeter Series "A" (14), and with those of numerous other investigations concerning potassium fixation. When this allowance is made, the effects of the treatments upon the exchangeable bases are generally in agreement with the trends indicated in Table 13. The small residue of sodium, not leached or removed by the crop, under the nitrate of soda treatment was mostly retained in the soil in the exchangeable form. In other cases, the ditferences in either di- rection in both comparisons are of insignificant magnitude. The calculated net effect on the lime requirement of the soil will be discussed in a later section. Total and Available Phosphorus Chemical analyses of the various soil layers removed from the lysimeter tanks in 1940 included determinations of both total phos- phorus contents and the amounts extractable by the ''available" phos- phorus method of Truog. The data are shown in Tables 15 and 16. The total phosphorus results are in remarkably good agreement with the lysimeter data regarding net gains during the experiment, as shown previously in Table 13. The increases in phosphorus, re- sulting from the fact that much greater amounts of this element were applied in the fertilizer than could be removed by the crop, are clearly shovra. This is especially true when unusually high amounts were applied, as in case of ammophos and, to a lesser degree, from fish meal, tankage and manure treatments, all of which supplied more than the usual amounts of phosphorus. It is to be noted that practically all of the accumulating) phos- phorus is represented in the surface soil. The only exceptions are those of nitrate of soda, nitrate of potash and ammophos, where there are significant gains in the subsoil, and even in the substratum, as in case of nitrate of soda. The gain in the subsoil from the ammophos treatment is probably due to the unusuall}^ high rate of application. 300 Connecticut Experiment Station Bulletin 458 Nitrate of soda and, to a lesser degree, nitrate of potash tend to per- mit greater downward movement of phosphorus, probably due to some formation of the more soluble phosphates of the sodium or po- tassium bases. It is to be noted that the drainage waters from the nitrate of soda tanks were the only ones to show leaching of meas- urable amounts of phosphorus. The data on available phosphorus give a much different picture. The gain in total phosphorus was rarely associated with a correspond- ing or proportionate gain in available phosphorus. In several cases, Table 15. Phosphorus (Total) in Soils, as Removed from Lysimeter Series B. Percent in various so 1 layers Surface Entire profile Nitrogen treatment soil Subsoil Substratum *in tanks Net gam A B C pounds per acre Nitrate of soda .1372 .0483 .0314 4864 464 Nitrate of potash .1375 .0425 .0293 4763 363 Nitrate of lime .1483 .0344 .0287 4777 337 Sulfate of ammonia .1520 .0344- .0290 4865 425 Ammophos .2571 .0476 .0280 7638 3238 Urea .1486 .0340 .0293 4780 380 Calurea .1516 .0341 .0287 4844 440 Cyanamid .1459 .0317 .0303 4668 468 Cottonseed meal .1500 .0337 .0303 4818 478 Castor pomace .1503 .0337 .0290 4807 407 Linseed meal .1490 .0359 .0283 4814 414 Fish meal .1671 .0344 .0280 5198 798 Dried blood .1449 .0357 .0287 4735 335 Tankage .1675 .0351 .0270 5214 814 Manure .1564 .0374 .0303 5068 668 No nitrogen .1540 .0377 .0290 5014 614 Original Soil, 1929 .1313 .0350 .0286 4400 Table 16. "Available" Phosphorus (Truog Method) in Soils^ as Removed FROM Lysimeter Series B. P. P. M in various soil layers Entire orofile Net gain Nitrogen treatment soil Subsoil Substratum in tanks or loss A B C pounds per acre Nitrate of soda 288 44 15 806 165+ Nitrate of potash 274 26 15 724 83-f Nitrate of lime 290 12 11 716 75-F Sulfate of ammonia 174 7 11 435 206— Ammophos 251 44 10 714 7i+ Urea 207 7 10 510 131— Calurea 238 7 9 580 61— Cyanamid 465 10 10 1112 471+ Cottonseed meal 173 7 9 431 210— Castor pomace 175 10 9 444 197— Linseed meal 180 11 12 462 179— Fish meal 333 11 9 810 169+ Dried blood 166 8 9 417 224— Tankage 321 9 9 776 135 + Manure 410 15 10 1000 359+ No nitrogen 319 18 8 781 140+ Original soil, 1929 244 24 9 641 Interrelations of Nitrogenous Fertilizers 301 the Truog method measured less avaihible phosphorus than in the or- iginal soil. These instances were generally associated with treat- ments that produced increasing soil acidity, unless an unusual amount of phosphorus was applied. When gains were obtained, the treat- ments had caused a lowering of acidity (higher pH), under equal phosphorus treatments. Larger amounts of total phosphorus in the subsoils from certain treatments were paralleled by increasing- amounts of available phosphorus, presumably due to the factors dis- cussed in the preceding paragraph. Total Potassium Determinations of total potassium in the soils were made in all cases. However, the variance of the results from replicate tanks was too great to permit measurement of significant differences between treatments. This is not surprising, since the total amount of potas- sium in the soil profile represents nearly 90,000 pounds per acre, and the difference that could be expected to result from even the unusually high potassium accumulation under nitrate of potash is only slightly more than 2 percent of this (see Table 13). Moisture Equivalent The moisture equivalents of the surface soil (A) samples, from tanks treated with manure showed a final average of 9.85 percent. This was 0.88 percent higher than the average of soils under all other treatments (8.97 percent). This is a reasonable result Avhen the increase in organic matter is considered. No other treatment pro- duced an appreciable or consistent change in the soil from this stand- point. However, it is to be noted that the "No nitrogen" treatment showed the lowest final moisture equivalent, at 8.42 percent, presum- ably in consequence of the loss in organic matter. The large gain in organic matter, as measured by the carbon determination from castor pomace (see Table 9) was not reflected in the moisture equivalent to a significant degree. There was no effect of any treatment upon the subsoil (B) or substratum (C) samples. The averages for these lior- izons, for all tanks, were T.OO percent and 6.11 percent respectively. SOIL CHANGES FROM NITROGENOUS FERTILIZERS, AS RELATED TO SOIL ACIDITY Samples of the surface soil, to the depth of 7 inches, were drawn from year to year to evaluate progressive effects of the treatments. A summary of these data is shown in Table 17. The measurements were made either in late fall, or in the early spring of the following year, in each case. The pH measurements during the first six years were by the quinhydrone electrode. Since 1936 the glass electrode method has been employed. After the fourth year, the reactions of the surface soil had ap- parently attained an equilibrium under a given treatment that was 302 Connecticut Experiment Station Bulletin 458 quite constant in most cases. It is to be noted that the soils received no nitrogen treatment in 1939, prior to the final pH measurements in the spring of 1940. The details of the leachings of calcium from year to year in the course of this experiment evidence the fact that the net gains or losses were much more pronounced during the first four years, under those treatments that produced the more acid conditions. The aver- age yearly leachings of calcium during the first four years were from 1% to 21/^ times as great as during the last four years of treatment. Table 17. pH Measurements of Surface Soil (A), in Fall or Early Spring Following Each Yearly Treatment, Windsor Lysimeter Series B, 1929-40. Year of experiment Nitrogen Treatment 1st 2nd 3rd 4th 5th 6th 7 th 8th 9th lOth 6.9 Final Nitrate of soda 6.1 5.4 6.4 6.5 6.3 6.9 6.9 6.8 7.0 5.9 Nitrate of potash 6.2 5.2 6.3 6.5 6.3 6.7 6.6 6.7 6.6 6.9 6.1 Nitrate of lime 6.0 5.1 6.3 5.9 5.8 6.1 6.0 6.1 6.1 6.2 5.8 Sulfate of ammonia 4.9 4.4 5.3 4.0 4.0 4.3 4.2 4.0 4.0 4.2 4.2 Ammophos 5.0 4.3 4.8 4.1 4.1 4.2 4.2 4.3 4.3 4.5 4.4 Urea 5.5 4.8 5.4 5.1 4.9 5.3 5.1 4.9 4.8 5.1 5.0 Calurea 6.0 5.1 5.7 5.3 5.1 5.5 5.4 5.2 5.2 5.3 5.0 Cyanamid 7.5 7.2 7.1 6.8 6.3 7.0 7.4 7.2 7.1 7.4 6.8 Cottonseed meal 5.3 4.6 5.6 5.1 5.0 5.3 4.9 5:0 4.8 4.9 4.7 Castor pomace 5.2 4.6 5.4 5.0 4.9 5.1 4.9 4.8 4.9 4.8 4.8 Linseed meal 5.4 4.5 5.6 5.0 5.1 5.0 4.9 4.8 4.8 4.9 4.7 Fish meal 5.3 4.7 5.3 5.1 5.0 5.1 4.9 4.9 4.9 5.0 4.9 Dried blood 4.9 4.6 5.4 4.7 4.7 4.9 4.8 4.8 4.7 4.9 4.7 Tankage 5.6 4.7 5.4 4.9 5.0 5.3 5.0 4.8 4.9 5.1 5.0 Manure^ 6.4 5.8 6.2 6.2 6.1 6.8 6.4 6.8 6.5 6.8 6.5 No nitrogen 6.1 5.6 6.2 6.0 5.7 6.3 5.9 6.Z 6.0 6.4 5.9 1 Containing some limestone. A more comprehensive evaluation of the effects of the various treatments in relation to soil acidity is obtained from the detailed base exchange studies of the final soil samples collected in 1940, These results are tabulated in Tables 18, 19 and 20, for the surface soils, subsoils and substratum samples, respectively. The effects of the different nitrogenous fertilizers on the individual exchangeable bases have been discussed in a previous section. Our present concern is with the total of the exchangeable bases, in equivalent terms, in re- lation to the base exchange capacity. The nitrogenous fertilizers of the more acid type (sulfate of am- monia and ammophos) have depleted the exchangeable bases to a very low relative base saturation throughout the soil profile. The other materials have produced no appreciable effects in the subsoil and sub- stratum layers. However, manure (containing limestone) had a more definite tendency than the other materials towards increasing the base status of the lower soil horizon. The pH values in the substratum samples were increased by the nitrate materials to a greater degree than would be expected from their total exchangeable bases. However, with so low a base ex- Interrelations of Nitrogenous Fertilizers 303 ^ < <■ ^ a C/2(i> OCV) CO lO 00 CO O IM ON o C^l 00 t^ CO CO I^ 2? CN T-H 00 CM ro o o 00 ^ocor^ ON -OCn ■+ CO T-H ■ i- 00 ^ C^J CO '-; cvqcjN CO COON ON lO coco CA OO CO TO ro^ ro "^On CO t^I cdt< ^ COMDMD CM ci<5 T-H* CO T-H QJ (^ vo u^ ir> T-H »— * CM CM CO T-H T-H T-H CM CM CM OO "^ ^ 0^.3) TO JD 0) 00 03 >' -c.-t: LOOOti coirj irtO m U-) CO CM T-H T-H CO T-H CM NO X it; d t< vd d \o d d lo K u-j irj Si ™ TO CO 0) -O Q) OOO CO OOn oo O '^'-11^ ON ON CVl CO CO On ^X 0\ CO CM ^. *-? CM ^ CO CJN 0.-H 00 t-hMD ^ ON O TO u UJ T-i cm' CM vrj \d ^^' ■^ loli-j ^' irj T^ CM CO is lO t~« »*■ CO lO wi O lO T-H (s) in CM cq-i-H 00 O^ t>. CO 00 ca »N vq !>. 00 T-H o o -a; CON -51; t>. T-H o H CO N CO d '-' i-t .-J uS ^ T-H 1-J T-H cH 1-H id cq C^j 00 \o vo t^\o VO^O VO VO ir> m r^ NO lO -* CNl CO Z OOO oo OO o OOO o oo o o O 0) 0) JD ^OnVO CM ^ n;"* C7^ ^"^O r^ ^ ■* i^ lO CO TO 0) CO ^ CO o^ CM ^_ '^.'t ^. CM CM CO CM CO CO ^^ NO ^ r— 1 c TO o X LLJ r^ cooo ,— 1 lo 0\ CM \o 1-H CO'^ 'j- NO U-) CM ,_, 00 00 00 lO-^^ CM CO Tj- CO CO CO CM_ CM co ^. '^. t^ CO 2 _ '"' Os 0\ -^ COt-I c:^oo 'i- O O VO ^ ONtV. IT) CO TO irj ^ C<1 ro^ VOOO o\ lO lO ■* f^ ^'^ 00 '^ CO U T^-r^ CM do do" ^ odd d c5<:S Ti^ '"' '"' rt ON c A o CM 0) _, cfl ON TO « 1 TO o o c B S rt rt a; g _^- 4= Ol >- So o'o'o <*H o rs (U O R CL) o be O 'o en 2- lU a; u 13 .S z cti cti c^ t^ u, ^. 5 s C3 ^ oi >> O O -u tn c O rt •- "tn 3 'S o '5) 'u sgs Du u UU J E QH ^ ^ O 304 Connecticut Experiment Station Bulletin 458 > < i^. be ^1 m c Eh OJ W pq CO < Q H VO ro (T) ^00 00 CO NO CO lO CO ON CO NO NO O 2^ ^ '^^O ^00 ^CNJ Cn| CO 'J-_NO_ li-5 NOON CO CM lO E^ ■O O MD -^^' irjio u-j irj u-j u-j lO u-j u-> no' NO irj c o ooq o 00 t>i ro CMVO CO CNJ cooo' q CONOt^ CO On NO On Q) « U-) irj lO CM CM -st- ^ '^ ^■^-^ ^ 'ef^ ID Tl- ^ '^ S! nj -Q cu 00 c (^ >' ^ t: O ro ON U-) O o t^ CM oor^ Q, fvi CO i oicMCNJ ro' CNJ (m' cm' CM CM (U u fU CQ _a) LOfVl r-l CO ON ^ss CO 1^ O-v ON NO ONt^ '^ ^ r^ cX O CO CO ON O CO Ol CO rg CM^_ <>a CO CO CM CO CO ^ ,-1 ,-( i-Scni T-H -—I ""^ T-l T_ r-l ""^ r-l T-H ^ '"' '"' X LU lo ^ 00 og ^ ^ en 0^ ^ CO M CO 00 CO VO i-H lO 03 ■5f 00^ lO o q 'H q R *^ 'I '-J 0^ 0\ "1 CO CO O 1— ^•^•.4 o d ^•^ ^•^^ 1-4 69 ON m lo '^-^ Tl-Tj- CO -* ^ CO I^ CM CO c^^ CO CO QJ z OOO oo oq q q q q q '-^. R q q q TO XI a> TO QJ co^ <>J U-) Ti- NO t^ ON 00-* NO CM Tt-'^ CO ■* ,_i ^ -sf-^oq CO (M_ i^^ CnI CnJ CnI CM (Nj CNI CM CO "*_ 00 1 c -C X LU U-) ^H o O^O ^ CO CNJ i-H O NO 00 t^T-H NO lO NO DO CO -^_ CO rvi c-Nj "*. '^. CO CO'st ^_ CO CO CO >J-) ^_ CO 00 .-1^ CO r^ cOio lO ooooo NO lO lO lO ON lO u lO l-O CO COr}- to CO -^^ CO ''^^ CO CO r^ ^_ ■LTi nS ■g si O ON CM QJ , en On E_ iS ^ - §o 00— o -^ M-l <-(_( M-H OOO OJ (U -.(:^ ^.t: t^ 00 00 (M\0 OO CO SO 00 00 00 '^^ vo CO u-> X TO '"' ""^ "^ -^o o_^ OS ^_oo OS 1 — 1 1 — 1 o ON OS Q) Q. n3 (Ni(M j rjcM r-< cvi osi i>i ,-h' <>iCM CM T-l' ^ QJ u ra m 0) XI QJ OS >— 1 CO t^^o OOO o i-H Tj- rvi SO Os t^ to tN^ u-) |x o o o OS 00 OS OO I—; OS OS O 00 OO OO OO OS -!= '-''-^'-' ^T^ O o '-' OO^' O ^■^ o' o O X LU 00 t^ vo lo vo <=>N CO \n 'i- \o CSJ lO t^ y-i vo O fTJ R ""1 "-J 't "1 ,-! CQ 00 ^T-tdS o q CM q q O i-< .— 1 i-H i-J i-H ,-i t-J 1-H -H CO (Nl -* ro OJ (M CSJ CO cofo ^CM CO ^ (Nl n3 OO O O o o OO o o o o o OO O q q Q) -Q QJ -Q QJ 00 '^ --I OS CM lo o (M so '-HIO CM t^ rs] ^ ^ 00 ^i^ ""l '^, '^. o--; rsj (Ni CM CsJ CM CVI rsj CM CM CO CM ao c ^ X LU 2 CO OlO 00 (M ro lO CO O OS u^ CO CO •^ '^ so in o^o T-H CVj ro^ u u-j '^ r>. lO lO ^_ -=}-_ u-> ^_ lO ^ ^. U-) -sT ^_ _rt C jC o CM QJ Cfi r ^^^ Os CD !^ QJ ro 4^ QJ go -o o P 1/1 *^^-. M-l *^ M-l o o o 1 en 3 'rt O o o 'o en q; (U a; ii& r- tH (L> s •^ bo O "rt iz rt cti c3 l-< iH )-< ^ s 03 ^ u o ° V. J2 2 " '5] Si^S co-< en o o 306 Connecticut Experiment Station Bulletin 458 change capacity, a small error in one or another of the determinations of individual exchangeable bases could appreciably change the ap- parent relative base saturation. The total base exchange capacities, given in Tables 18, 19 and 20, represent averages between the value, as determined by ammonia re- placement in the method of Pierre and Scarseth, and the total, as de- termined by adding the total of the individual bases to the exchange- able hydrogen as determined by barium replacement. Conversely, exchangeable hydrogen represents the average between that measured directly and that obtained by difference. The separate data from the two standpoints were in fair agreement. However, it is reason- able to expect that a more accurate picture is presented by combin- ing them, as indicated above. The apparent base exchange capacity of the surface soil, thus computed, appears to be increased to some extent by ammophos, cyan- amid or manure. The other values are reasonably close, in all cases. The differences in organic matter content at the end of the experiment, previously given in Table 8, are not reflected in the total base ex- change capacity measurements, except in the case of manure. Evaluating Acid or Basic Effects of Fertilizers At present, the equivalent acidity or basicity of fertilizers is us- ually estimated from tables based on the data of Pierre (16). These are developed from an assumption that under cropped conditions one- half of the nitrogen exerts an acid effect corresponding to its equiva- lent in nitric acid, and that the "ash" constituents exert net effects corresponding to the balance between their basic and acidic com- ponents. The following materials, used in this experiment to pro- vide phosphorus, potash and magnesia, tended toward increased ba- sicity : precipitated bone, carbonate of potash and carbonate of mag- nesia. Sulfate of potash (supplying one half of the potash) should be neutral in its effects. Since some of the nitrogenous fertilizers supplied other of the conventional "plant food" constituents, the amounts of the supplemental materials were not the same' in all cases. The computed acidity or basicity from the nitrogenous materials and from other sources, using Pierre's procedure, are shown in Table 21. These represent the totals of all treatments during the 11 year period. The actual effects of the treatments upon the soil can be evalu- ated from two standpoints : in terms of net gain or loss in exchange- able bases and in terms of decrease or increase in exchangeable hy- drogen. Since these are inter-dependent, except when there is some change in base exchange capacity, a combination of the two computa- tions should provide a fair picture of the net soil effects with respect to soil acidity. All three of the soil layers must be combined in order to show the full action of the treatment. Another means of measurement of the net effects of the treatment, Interrelations of Nitrogenous Fertilizers 307 Table 21. Computed Equivalent Acidity or Basicity of all Fertilizer Treat- ments, Applied from 1929 to 1939, Inclusive, Windsor Lysimeter Series B. (Expressed as calcium carbonate equivalent, per acre.) B — basic, A — acid. Nitrogenous Other Nitrogen source material materials Net total Nitrate of soda 3600 B 3145 B 6745 B Nitrate of potash 3600 B 2025 B 5625 B Nitrate of lime 2700 B 3145 B 5845 B Sulfate of ammonia 10,700 A 3145 B 7555 A Ammophos 10,700 A 2565 B 8135 A Urea 3600 A 3145 B 455 A Calurea 2340 A 3145 B 805 B Cyauamid 5700 B 3145 B 8845 B Cottonseed meal 2900 A 1731 B 1169 A Castor pomace 1800 A 1530 B 270 A Linseed meal 2980 A 1905 B 1075 A Fish meal 1800 A 2125 B 325 B Dried blood 3500 A 2973 B 527 A Tankage 3000 A 2565 B 435 A Manure 8500 B 295 B 8795 B No nitrogen 3145 B 3145 B from the standpoint of base depletion or accumulation is provided by the lysimeter data on drainage water losses and by the crop removal data, in relation to the amounts added to the soil. The bases most directly concerned are calcium, magnesium, potassium and sodium. However, since acid reacting fertilizers cause significant removals of manganese and aluminum from the soil through leaching or in the Crop, it may also be considered that these represent base depletion by the treatment. Table 22 shows the results of the above schemes for Table 22. Evaluation of Net Changes in Base Status of Soil During Lysime- ter Experiment B, 1929-'39 Inclusive, Computed as Calcium Carbonate Equivalent. (In pounds per acre.) B — more basic, A — more acid. From base exchange data From lysimeter data^ Nitrogen treatment Surface All three Not including Including soil only soil layers Mn and Al Mn and Al Nitrate of soda 1363 B 1636 B 1541 B 1538 B Nitrate of potash 811 B 1207 B 2104 B 2100 B Nitrate of lime 1110 B 1232 B 3039 B 3034 B Sulfate of ammonia 2101 A 3624 A 3055 A 3391 A Ammophos 2248 A 3743 A 2936 A 2989 A Urea 937 A 1095 A 1320 A 1347 A Calurea 1024 A 971 A 552 A 573 A Cyanamid 3145 B 3879 B 8239 A 8234 A Cottonseed meal 1673 A 1741 A 1909 A 1930 A Castor pomace 1765 A 1846 A 1704 A 1727 A Linseed meal 1840 A 1872 A 1731 A 1754 A Fish meal 1466 A 1469 A 353 B 321 B Dried blood 1696 A 2000 A 2149 A 2187 A Tankage 1432 A 1743 A 240 A 261 A Manure (incl. lime) 3432 B 3779 B 9721 B 9718 B No nitrogen 449 B 491 B 1954 B 1952 B 1 Representing net gains oi- losses due to both crop removal and leaching. 308 Connecticut ExpenTnent Station Bulletin 458 evaluating soil changes, from the standpoint of the acid or basic ef- fects of the treatments. The influences of treatment upon the soil are most reflected in the changes in the surface soil layer. However, in some instances, an appreciable effect is also exerted upon the subsoil or substratum, or both, as previously discussed. Lysimeter data indicates net changes of similar magiiitude, when the fertilizers have tended to in- crease the acidity. Fish meal is the only treatment which has made the soil more acid, when the lysimeter data would indicate a slight basic effect. Those treatments that have supplied much calcium, such as nitrate of lime, cyanamid and manure (containing some limestone), have influenced the exchangeable base status of the soil to a much lesser degree than would be indicated by the net accumulation of bases, chiefly calcium, as computed from the lysimeter "balance sheet." It is apparent that much of the calcium thus added to the soil is not accounted for in the base exchange relationships of the soil, under the conditions of this experiment. In comparing these data with the estimates shown in Table 21, it is apparent that the quantitative effects of the treatments in most cases are quite different from those predicted on the basis of Pierre's methods of computation. The lysimeter data on basic fertilizers sup- plying much calcium tend to follow the estimates. Some of the or- ganic materials show fair agreement, either from the base exchange or "lysimeter net change" standpoint. On the other hand, the soil ef- fects of treatments including the nitrate materials and the ammonia salts have been much less basic and much less acid, respectively, in any method of evaluation, than predicted from the Pierre computa- tion. The failure of nitrogenous fertilizers to develop their full the- oretical acid or basic effects under acid soil conditions has been dis- cussed by the senior author in a previous publication. Briefly stated, the following factors tend to modify the results actually obtained in practice : 1. All of the nitrogen in the material is not transformed to nitrates, unless the nitrogen is supplied as nitrate salts. 2. Under acid soil conditions, nitrates, sulfates and other acidic constituents combine with aluminum, manganese, iron and perhaps other cations that may not be directly derived from base exchange complex. Thus they leach, or are removed by the crop, without corresponding deple- tion of the important exchangeable bases (calcium, mag- nesium, potassium and sodium). 3. Some nitrogen is leached from sandy soils as ammonium salts. This nitrogen fails to accomplish base depletion Interrelations of Nitrogenous Fertilizers 309 of the soil, and permits acidic constituents to leach with- out affecting the soil bases. 4. Some nitrogen is assimilated by the crop as ammonium ions. 5. Basic constituents may accumulate in the soil in non- exchangeable form. Conversely, basic constituents may be liberated directly from the mineral components of the soil, permitting losses of soil bases by leaching or crop removal, without corresponding depletion of the bases absorbed in exchangeable form. 6. The chemical analyses of the tobacco crops harvested in this experiment do not indicate that any appreciable amount of nitrogen is thus removed from the soil with- out corresponding amounts of bases. (This will be dis- cussed in the following section.) Thus nitrate with- drawn by the crop is practically as effective in base de- pletion of the soil as nitrate leached by drainage water. Unfortunately, this experiment does not permit the direct evalu- ation of the effects of nitrogenous fertilizers alone, since other m.ate- rials, tending toward increasing the base status of the soil, were added to produce a "complete" fertilizer mixture. However, one may make a reasonable estimate by correcting for the effects of the "no nitro- gen" treatments, when the same amounts of other materials were used, and by proportional correction where less than normal application of the basic materials (precipitated bone, carbonate ef potash and car- bonate of magnesia) were employed. A limitation of this procedure is the failure to recogriize differences in amounts of soil-derived Table 2Z. Estimated Equivalent Acidity or Basicity of Nitrogenous Eertilizer Materials, as Determined in Windsor Lysimeter Experiment B. (Expressed as calcium carbonate equivalent, per unit of nitrogen^ in pounds per acre. Corrected for effects of other materials.) A — acid, B — ■ basic. Computed from Computed from Treatment base exchange lysimeter Average data data Nitrate of soda 11.4 B 4.1 A Z.l B 36.0 B Nitrate of potash 8.9 B 8.4 B 8.7 B 36.0 B Nitrate of lime 7.4 B 10.8 B 9.1 B 27.0 B Sulfate of ammonia 41.2 A 53.4 A 47.3 A 107.0 B Ammophos 41.4 A 45.8 A 43.6 A 107.0 B Urea 15.9 A 33.0 A 24.4 A 36.0 A Calurea 14.6 A 25.3 A 19.9 A 23.4 A Cyanamid 33.9 B 62.8 B 53.9 B 57.0 B Cottonseed meal 20.1 A 30.0 A 25.1 A 29.0 A Castor pomace 20.9 A 26.8 A 23.8 A 18.0 A Linseed meal 21.7 A 29.4 A 25.5 A 29.8 A Fish meal 18.0 A 10.0 A 14.0 A 18.0 A Dried blood 24.6 A 40.3 A 32.5 A 35.0 A Tankage 21.4 A 18.5 A 20.0 A 30.0 A 120 pounds, or equivalent to 1 percent per ton. 310 Connecticut Expeimnent Station Bulletin 458 nitrates that may be produced in the various instances. However, it will serve to give a direct comparison between the various nitrogen- ous materials, from the standpoint of their acid or basic effects upon the soil. The results of these computations, both on the bases of soil data for the entire profile (all three layers) and as computed from the lysimeter data, are shown as Table 23. These are calculated in terms of calcium carbonate equivalent, per unit of nitrogen (20 pounds) , for convenient comparison with the Pierre values. Estimates of equivalent acidity or basicity of fertilizer materials, as computed by Pierre's method, do not exactly account for the amounts of basic and acidic elements added to the soil in the fertilizer mixtures and in the rainfall, as shown in Table 2. Using this data, their theoretical effects may be calculated. Assuming all of the nitro- gen as potentially acid, the following corrections can then be applied: 1. Nitrogen recovered in crop and leaching, in excess of addition, represents additional potential acidity. When the recovery is incomplete, the difference signifies dim- inished acid effects. 2. Nitrogen leached as ammonia counteracts the effects upon the soil of an equivalent amount of acid, and must also be deducted from the total nitrogen recovery. Table 24. Computations of Acidic and Basic Effects of Treatments Based on Amounts of Various Constituents Added to Soil/ with Corrections for Incomplete or Excess Nitrogen Recovery in Crop and Leaching. Nitrogen Leached as Ammonia and Lack of Balance of Basic and Acidic Constituents in the Crop. Windsor Lysi- meter Experiment B, 1929-'39, Inclusive. (Expressed as CaCos equivalent, in pounds per acre.) A — acid, B — basic. Correction Correction Correction Net- Computed from from nitrogen from from crop theoretical Nitrogen source constituents recovery ammonia unbalance basicity added to soil data leaching data or acidity Nitrate of soda 2322 B 264 A 69 B 644 B 2774 B Nitrate of potash 1961 B 243 A 61 B 342 B 2121 B Nitrate of lime 2379 B 254 A 43 B 346 B 2514 B Sulfate of ammonia 11,043 A 747 A 224 B 1143 B 8929 A Ammophos 98Z1 A 675 B 57 B 1470 B 7619 A Urea 3922 A 1300 B 29 B 613 B 1980 A Calurea 2493 A 582 B 39 B 705 B 1167 A Cyanamid 5572 B 1472 B 59 B 578 B 7681 B Cottonseed meal 4771 A 1915 B 43 B 478 B 2335 A Castor pomace 4175 A 1622 B 45 B 606 B 1902 A Linseed meal 4349 A 1704 B 39 B 577 B 2029 A Fish meal 2901 A 1729 B 40 B 408 B 724 A Dried blood 4825 A 1307 B 29 B 686 B 2803 A Tankage 2720 A 1400 B 39 B 390 B 891 A Manure (with lime) 6180 B 3036 B 40 B 222 A 9034 B No nitrogen 3213 B 1722 A 36 B 85 A 1442 B I Computed from Table 2. Interrelations of Nitrogenous Fertilizers 311 3. The lack of balance between basic and acidic constituents in the crop diminishes the acid effect of the nitro<^en, Avhen acidic constituents are in excess, or vice versa. (Thus, Pierre assumes that one-half of the nitrogen in the treatment is thus involved.) This scheme of evaluation has been employed, with results as shown in Table 24. The net theoretical effects of the treatments from this standpoint are in general agreement with the lysimeter data on net gains or losses in bases shown in Table 22, except with respect to the very strongly acid sulfate of ammonia and ammophos treatments. It seems ap- parent that, after the soil has been greatly depleted of bases by these materials, additional amounts of the acid-forming fertilizer cannot exert their normal effects in diminishing the base status of the soil. Acid-Base Balance in Tobacco Crops The data on the average composition of the crops harvested dur- ing the years when nitrogen treatments were applied (1930-'38), pre- viously shown in Table 5, may be used to compute the acid-base bal- ance in the crop. The ion equivalent ]3er million of dry weight is a unit of convenient magnitude to show this relationship. When the acidic constituents (anions), assuming all nitrogen taken up as the nitrate, were found to be in excess of the basic constituents, one-half of the difference was deducted from the nitrate and entered in the table as the ammonium ion. When the basic constituents were in ex- cess, as in two cases, the difference was assumed as undetermined or insufficiently measured anions. The results of these computations of acid-base balance in the tobacco crops are shown as Table 25. Table 25. Acid-Base Balance in Tobacco, Computed from Weighted Average Composition of Nine Crops Grown in Windsor Lysimeter Experiment B, 1930-'38. (Based on dry weight, not including roots.) lor equivalents , in parts per million Total Ca tions Anions balanced ) Un- equiva- K 701 Ca Mg Na Mn NHi NOa SOi H2P0i 74 CI 67 det. lents Nitrate of soda 509 328 265 ? 207 1778 93 2012 Nitrate of potash 1055 409 308 74 2 98 1717 76 58 95 1946 Nitrate of lime 669 845 291 29 3 101 1700 98 65 73 1938 Sulfate of ammonia 668 509 303 38 27 607 1614 353 88 97 ^ 2152 Ammophos 573 424 357 23 32 543 1535 198 128 91 1952 Urea 653 624 346 31 18 176 1587 112 67 82 1848 Calurea 663 694 330 25 13 180 1642 113 67 83 1905 Cyanamid 678 744 222 28 3 184 1579 138 60 82 — 1859 Cottonseed meal 625 459 2>72 27 13 132 1367 127 60 74 1628 Castor pomace 604 534 308 27 14 150 1370 109 58 100 1637 Linseed meal 625 509 328 28 14 137 1376 124 63 78 1641 Fish meal 586 634 289 28 12 110 1361 126 67 105 1659 Dried blood 576 534 307 28 23 158 1348 115 51 112 1626 Tankage 617 629 301 29 11 98 1387 119 68 111 — 1685 Manure (limed) 553 499 2,22 28 2 — 1021 127 7?> 112 71 1404 No nitrogen 571 404 252 34 3 — 835 191 84 100 54 1264 312 Connecticut Experivient Station Bulletin 458 It is evident that most of the nitrate nitrogen is taken up with equivalent amounts of base (excluding ammonia) in all cases. How- ever, there is definite evidence that there are significant withdrawals of ammonia nitrogen by the crop when nitrogen is applied directly in this form. In other instances the lack of balance, assuming all of the nitrogen to be taken up as nitrate, fails to give convincing proof of ammonia utilization by the crop. However, it is notable that the two treatments that have failed to properly meet the needs of the crop for normal growth (manure and no nitrogen) both show an ap- parent excess of basic constituents. These data give a strikingly different picture from that given by the computations of Allison (1) from various analyses of other crops. They also fail to confirm the estimate of Pierre that one-half of the applied nitrogen is taken up by the crop without removing equivalent amounts of bases, in so far as the tobacco crop is concerned. They further substantiate the preliminary findings of the senior author (14), reported in a previous publication. CONSTITUENTS LEACHED AND REMOVED BY CROP IN RELA- TION TO SEASONAL DISTRIBUTION OF LEACHING As indicated in a previous section of this bulletin, intensive leach- ing during the growing season occurred in only one year, 1938, when the rainfall was so heavy during the growing season that all crops isuffered severely from nitrogen depletion, regardless of the nitrogen source. On the other hand, in one season, 1933, the yields were so diminished by insufficient rainfall as to cause abnormally low crop withdrawals of nitrogen. The season of 1930 was also dry. The data for that year was somewhat abnormal, due to the residual effects of the 1929 crop, returned to the soil after severe hail damage. In the other six years, the crop yields were normal, and their nitrogen with- drawals were of consistent magnitude. In three of these years, 1931-'32, 1935-'36 and 1936-'3T, leachings during the fall, up to the end of November, were not sufficient to fully deplete the nitrate nitro- gen from the soil, as shown by the leachings resulting from heavier winter and spring precipitation. Lysimeter data for these years, in comparison with the other three years (1932-'33, 1934-'35 and 1937- '38) when nitrates were exhaustively leached during the first six- months period, serve to show the extent to which nitrate nitrogen is related to the removals of other constituents from the soil. These comparisons are presented in Tables 26 and 27. Treatments show- ing no consistent differences, as compared with similar materials in- cluded, have been omitted. It is to be noted that the nitrogen leachings (as nitrate) follow- ing the summers of more abundant precipitation were uniformly smaller. No appreciable amounts of ammonia from any treatment appeared in the drainage water during the six years under consider- ation in this comparison. (Ammonia leachings of considerable mag- nitude from the sulfate of ammonia treatment were observed follow- Interrelations of Nitrogenous Fertilizers 313 Table 26. Acidic Constituents Removed by Leaching and Crop, in Years with Low (1) AND High (h) Volumes of Leaching During the First Six-months Period (1). Volumes of Leaching During the Second Six-months Period (2) Abundant in Both Cases. (Yearly average oi three-year groups, in pounds per acre.) Nitrogen Sulfur 1 Bicarbonate Phosptiorus Treatment (1) (h) (1) (h) (1) (h) (Ij (h) Nitrate of soda Leached — 1 63.3 89.0 23.0 62.0 25.3 117.1 0.5 Leached — 2 53.6 7.2, 45.7 14.0 171.7 112.3 Crop 105.3 100.7 6.0 5.6 8.6 8.1 Total 222.2 197.0 74.7 81.6 197.0 230.0 8.6 8.6 Nitrate of potash Leached — 1 53.7 64.3 8.0 21.3 20.0 69.0 Leached — 2 58.3 9.0 32.0 14.3 100.0 69.3 Crop 99.3 108.3 4.3 4.7 7.5 8.6 Total 2n.3 181.6 44.3 40.3 120.0 138.3 7.5 8.6 Nitrate of lime Leached — 1 44.0 62.7 14.0 40.0 17.0 49.0 Leached — 2 56.7 9.0 53.7 23.7 63.0 43.3 - — - Crop lOLO 110.3 6.3 8.3 • 7.8 8.8 Total 20L7 182.0 74.0 72.0 80.0 92.3 7.8 8.8 Sulfate of ammoni; Leached — 1 43.3 91.3 2,6.7 124.6 13.3 33.0 Leached — 2 73.7 7.2> 197.0 91.0 22.7 20.0 Crop 65.3 69.7 11.0 17.7 5.0 5.3 Total 182.3 168.3 244.7 233.3 36.0 53.0 5:0 5.3 Ammophos Leached — 1 28.7 67.7 22.0 57.0 17.7 55.0 Leached — 2 75.3 14.7 82.0 42.0 62.3 36.0 Crop 80.7 86.7 9.7 12.0 10.9 10.7 Total 184.7 169.1 113.7 111.0 80.0 91.0 10.9 10.7 Urea Leached — 1 30.7 35.0 12.3 Z6.7 19.0 54.0 ■ Leached — 2 48.0 7.Z 53.0 27.7 51.3 41.7 . Crop 91.3 92.3 6.2, 7.3 7.8 7.1 Total 170.0 134.6 71.6 71.7 70.3 95.7 7.8 7.1 Cyanamid Leached — 1 19.3 56.3 13.3 32.0 22.3 48.0 Leached — 2 57.0 11.0 54.0 27.7 69.0 48.7 Crop 90.7 88.7 6.3 9.7 6.6 6.5 Total 167.0 156.0 73.6 69.4 91.3 96.7 6.6 6.5 Cottonseed meal Leached — 1 23.3 39.7 13.7 32.3 24.7 59.0 Leached — 2 46.3 9.7 45.7 24.0 65.0 43.0 Crop 81.7 80.7 7.3 9.3 7.0 6.9 Total 151.3 130.1 66.7 65.6 89.7 102.0 7.0 6.9 Castor pomace Leached — 1 26.7 47.0 13.3 33.0 25.3 57.7 Leached — 2 45.7 10.0 46.0 25.7 61.0 44.7 Crop 83.3 79.7 6.0 8.3 . 6.5 6.9 Total 155.7 136.7 65.3 67.0 86.3 102.4 6.5 6.9 No nitrogen Leached — 1 7.0 15.0 15.7 39.0 23.3 58.7 Leached — 2 22.0 4.7 56.0 22.3 78.7 41.7 Crop 22.3 19.3 5.0 5.7 4.2 5.0 Total 51.3 39.0 I 76.7 67.0 102.0 100.4 4.2 5.0 314 Connecticut Experitnent Station Bulletin 458 Table 27. Basic Constituents Removed by Leaching and Crop, in Yeabs with Low (1) and High (h) Volumes of Leaching Duriijg the First Six-months Period (1). Volumes of Leaching During the Second Six-months Period (2) Abundant in Both Cases. (Yearly averages of three-year groups, in pounds per acre.) Calcium Magnesium Potassium Sod urn Treatment (1) (h) (!) (h) (1) (h) (1) (h) Nitrate of soda Leached — 1 15.0 24.0 2.7 5.3 15.7 30.7 82.7 183.0 Leached — 2 26.3 12.7 8.3 2.2 24.3 11.7 155.0 52.3 Crop 37.0 ?>7.i 14.3 15.3 97.0 98.7 17.0 28.0 Total 78.3 74.0 25.3 22.9 137.0 141.1 254.7 263.3 Nitrate of potash Leached — 1 23.0 32.3 5.7 8.0 82.7 141.0 5.3 8.0 Leached — 2 58.7 16.7 12.0 3.0 153.3 69.7 7.7 4.3 Crop 28.3 35.3 15.0 15.3 156.3 176.3 5.0 7.2 Total 110.0 85.3 32.7 26.3 392.3 387.0 18.0 19.6 Nitrate of lime Leached — 1 56.7 97.3 6.3 7.2 22.3 48.3 2.7 6.0 Leached — 2 107.3 42.3 11.7 6.7 45.0 23.3 6.2 3.0 Crop 61.7 86.0 14.0 16.0 94.0 108.3 2.2 3.0 Total 225.7 225.6 32.0 30.0 161.3 179.9 12.3 12.0 Sulfate of ammonia Leached — 1 35.7 115.3 8.0 19.7 44.6 126.3 5.0 9.3 Leached — 2 128.7 45.7 19.7 , 5.7 119.0 52.7 9.7 4.0 Crop 22.7 21.0 8.3 10.0 51.3 61.7 2.0 2.0 Total 187.1 182.0 36.0 35.4 214.9 240.7 16.7 15.3 Ammophos Leached — 1 29.3 68.3 8.0 16.7 27.2 86.3 5.3 13.3 Leached — 2 91.7 2,7.7 28.0 7.6 84.0 41.3 13.0 5.0 Crop 30.3 22.0 13.0 14.0 60.7 65.0 1.7 2.0 Total 151.3 128.0 49.0 38.3 182.0 192.6 20.0 20.3 Urea Leached — 1 Zi.Z 50.0 5.0 8.0 31.3 59.7 4.3 6.7 Leached — 2 75.3 30.7 13.7 4.0 64.0 34.0 7.0 2.7 Crop 46.0 48.7 12.7 18.3 88.3 98.0 3.0 3.0 Total 154.3 129.4 31.4 30.3 183.6 191.7 14.3 13.4 Cyanamid Leached — 1 26.6 26.2 2.3 6.4 25.7 62.3 2.2 7.0 Leached — 2 97.3 42.3 13.0 2.2 64.3 32.0 5.7 2.7 Crop 60.0 51.0 7.2 9.0 93.0 97.0 2.7 2.0 Total 183.9 129.6 22.6 18.7 183.0 191.3 11.7 13.4 Cottonseed meal Leached — 1 25.6 47.7 4.3 10.0 33.0 71.3 4.3 7.0 Leached — 2 64.7 29.3 16.7 4.3 66.7 36.0 6.7 2.7 Crop 34.7 39.0 19.7 19.0 87.3 100.0 2.3 2.7 Total 125.0 116.0 40.7 33.3 187.0 207.3 13.3 13.3 Castor pomace Leached — 1 29.0 49.3 5.0 10.3 35.3 77.0 4.7 7.2 Leached — 2 69.0 31.7 14.3 2.7 66.2 36.7 7.0 2.2 Crop 38.7 43.3 15.3 15.0 82.7 93.0 2.7 3.0 Total 136.7 124.3 34.6 29.0 184.3 206.7 14.4 13.6 No nitrogen Leached — 1 14.0 33.0 2.7 5.3 25.0 59.3 2.3 5.7 Leached — 2 48.3 17.3 9.3 3.0 64.7 27.3 5.7 2.7 Crop 12.7 15.0 5.3 5.3 32.0 43.0 1.0 2.0 Total 75.0 65.3 17.3 13.6 121.7 129.6 9.0 10.4 Interrelations of Nitrogenous Fertilizers 315 ing the extremely heavy midsummer rains of 1938.) It is difficult to account for the consistently diminished nitrogen recovery in the years with greater summer rainfall. However, two possibilities seem most logical. Micro-biological activities are more active in soils that do not become too dry during the warmer months. Thus more nitrogen is temporarily tied up in microbial protoplasm. Also, somewhat warm- er, less excessively wet soil conditions prevailed during the fall months in the years with greater nitrogen liberation. Nitrogen in the root residues of the crops was thus more likely to have been liber- ated by the organisms effecting their decay. However, nitrogen re- coveries under the various treatments were proportionally similar in both groups of years, except for urea, which gave unusually low leachings in the years marked by wetter summers. Smaller propor- tions of the nitrogen were accounted for in the leachings from the nitrate treatments during the second period, especially in the "dry summer" years. However, in both cases, the crops obtained more nitrogen from these materials. Sulfur was lost by leaching in greater relative proportions than nitrogen during the second six-months period. Even in the wetter years, the later sulfate leachings were considerable. Bicarbonates also persisted in, the drainage water during the second period, after nitrate had been greatly depleted. Interesting differences in bicar- bonates in the drainage water were observed between the various treat- ments. Unusually high amounts under nitrate of soda, and low quantities under sulfate of ammonia, are noted. Phosphorus, not leached to a measureable degree except under nitrate of soda in wet seasons, was removed by the crop in general proportion to the yield, with no consistent relation to seasonal leach- ing. Of the basic constituents, calcium was usually higher in the crop in the wetter seasons, except for strongly acid sulfate of ammonia and ammophos treatments. Here, in spite of lower nitrogen intake in the drier summers, more calcium was removed by the crop. How- ever, in general, less calcium was removed by the drainage water in the years of more abundant early leaching, thus giving generally less total calcium losses. JSTitrate of lime and cyanamid, supplying sim- ilar amounts of calcium, provide marked contrasts in calcium leach- ings and crop withdrawals. Drainage losses were much greater un- der the former treatment. Cyanamid materially affected the calcium in the crop, but did not produce more in the drainage water than other treatments supplying no unusual amounts of this constituent. This is to be expected when it is considered that nitrates are the chief factor in calcium depletion by leaching. Crop removals of potassium represent much larger proportions of total losses than those of calcium. It is also noted that potassium persists to a greater degree in the second period of the wetter years. Hence losses of this element are greater in years when there are greater volumes of leaching. 316 Connecticut Experhnent Station Bulletin 458 Magnesium leachings in relation to the distribution of drainage water collections tend to run parallel to those of calcium. However, magnesium is generally higher in the crop in the wetter seasons, in opposition to the trends for calcium and potassium. Crop removal of magnesium constitutes a large share of the total magnesium loss. Sodium losses by leaching are in general relation to the distribu- tion of leaching volume, by periods. However, except in case of the nitrate of soda treatment, the amounts involved are too small for adequate comparison. The tables do not include available data on chlorides, manganese and aluminum. Chlorides leached similarly to nitrates. However, since substantial increment continue to enter the soil by atmospheric precipitation throughout the year, the later periods tend to yield sustained chloride leachings. Manganese was not leached to a meas- urable extent, except under the two most acid nitrogen treatments. However, liberation of manganese by the soil under other treatments is revealed by the manganese in the crop, in general relation to the acid or base tendency of the fertilizer (see Table 23). Aluminum was not determined in the crop. It was a constituent of drainage water under the sulfate of ammonia treatment in the later years of the experi- ment. Anunonia nitrogen leachings were inconsequential, usually not more than a pound per acre per year, except as a result of the wet summer of 1937 and the extremely heavy July rainfall of 1938, when June nitrification was presumably more complete than under sulfate of ammonia, leaving no ammonia residue to be leached in the follow- ing month. The effects of seasonal conditions on the actual composition of the tobacco crop is best shown by expressing the various constituents on an equivalent basis., as shown in Table 28. These data represent the weighted averages of the crops grown during the three years of pre- vailing low rainfall (1) and the three years of abundant rainfall (h) during the growing season, discussed in the preceding paragraphs. The nitrogen in the crop has been apportioned between nitrates and ammonia, as required, in order to adjust the acid-base balance. The apparent intake of nitrate nitrogen per unit of dry weight pro- duction is similar in both wet and dry years, and is in general rela- tionship to the nitrate supply in the soil during the growing period. Leaching from the root zone was not sufficient to limit nitrate assim- ilation to a material degree, in years under consideration. However, in the wetter years the rate of nitrate intake was usually somewhat less. The larger crops in the wetter seasons usually more than offset this difference, as previously shown in Table 26. In most instances apparent ammonia absorption was greater in the drier years. However, the reverse is true for those treatments that were most likely to provide considerable amounts of ammonia Interrelations of Nitrogenous Fertilizers 317 Q "*■ l-c ° a ft ^ o ■" p o « 2; 9 > o ^ •- 2 S o « S w >H o « w ^ •a < •0 0) ^ QJ TO "m r^i CM 0 CM 00 '^ On On) on LO r^ t^ NO •^1 c^, 1- NO i5 o" 0 <" 0\ 0 0 ON On 0^ ^ CM On 0 ON t^ l~^ 0-. NO NO t^ 10 fV) CO T-l (M fN] — 1 T— t T— ( CM CM 1 1 T-H 1 1 T-H * — ^ 1 — 1 r-^ j—\ ^H , 1 ,-H T-H H 1 r^ 1 CO C 1 T-H 3 1 •^00 ro ro On 00 00 ON VO -^ T-H LO 00 CM <0 NO NO NO r^NO 10 0 r^ t^ U-> NO NOI^ NO IJ^ t^NO Nooo r^t^ r^ t^ 0 CO U ^ to T-l 00 U^ u-> .— 1 00 00 CO ON T* 00 LO T-H T-I 00 00 LO ^ -* 0 r^r^ \o ^ NO NO r^r^ CM r-l r^ LO LO NO NO LO LO LO 00 ON Q. T-H T-H c 0 c f < 0 VO 10 ON CM CO t>^ CO ot^ rf LO 000 (Mt^ LO 0 I-^'* 0 Ul 0 0\ I^ vo O.-' CM 0 CO 10 T-H 10 CM CM ^^ CO 0 CM ^ 0 CO 00 0 ,-H CM — ro CM m On 00 CO CO CM ,-H NO t^ CM LOON 00 CM NO CM CM '^ 6 u-5 .— ( CO "—I CTn no vo CM irj NO NOLO 0 T-I T-H 00 00 CO r^ ON t^oo cot^ NO NO NO NO LO 10 NO LO LO t^ Tf- CO ■* CO' 00 1>. ~ ro (M NO NO co>-i t^ r^ CM CO CO CM T-I CM NO CO 10 VO NO 1 X ON NO ro 00 I^ U-) NO ^ in NO CO T-H NO'CO CO 00 00 On 00 1 z (M t-H ^ '"' vn NO T)- LO CM T-i T-H CnI t-H '"' c 2 CNI CM roCNJ rt CO 0 LO CO U-J CM LO ■>+ CO LO CO NO LO COrJ- CO CM CO CO CM T-H T-H ,-H T-H ,-H TO .—(NO r-( iri NO 00 . LO 10 NO NO NO t^ LO NO 10 LO ■^ NO T-H T-H D. -a '-'^ i_ 0000 1^00 NO NO 0 10 0 CM r-x NO LO CO 0 I^ ^0 t^T-H 9i> 0 S O"^ ONt^ u-J On OON 00 T-H (M LO CMl^ "* Tf NO On NO 't 00 d r^ NO vo CM 00 uo T-H T-H 00 On ^ ON 00 CO r^ON LO On NO t^ m-C ,^ CO CO CO -^ CO -^ CM CM cni cm COCO CO CO CO CO CO CO >.5P-Q < > 0 0 in 03 0 g s 2 CO < P u u u ^ 318 Connecticut Experiment Station Bulletin 458 nitrogen in the soiL during the growing season: sulfate of ammonia, ammophos and cyanamid. As pointed out in the previous section, the total base intake per unit of dry weight is chiefly determined by the nitrate assimilation. However, the distribution of the bases is conditioned by their rela- tive availability, as affected by base exchange interactions with the soil solution. An interesting example is provided by the magnesium content of the tobacco under C5^anamid and cottonseed meal treat- ments. In the former case, the soil is so well supplied with exchange- able calcium that a high proportion of this base is taken up by the crop, thus depressing magnesium intake. On the other hand, cal- cium supply under the cottonseed meal treatment is lower than nor- mal, permitting a larger removal by the crop. The reciprocal rela- tions between the various bases are so complex that no consistent differences between intake of any single base, under the various treat- ments, can be ascribed to seasonal factors. Bailey and Anderson (4) have pointed out interesting differences in the chemical composition of Havana seed tobacco as affected by dry or wet season. Their data show similar discrepancies due to reciprocal effects. Potash was con- sistently higher in the crop in wet years in one series where the only variable was the source of potash. On the other hand, in a lime series liming appeared to accentuate a generally higher potash content in the wet year. Similar contradictions would be indicated in the pres- ent experiment, comparing the nitrate of lime and cottonseed meal, for instance. CONCLUSIONS ON VARIOUS NITROGENOUS FERTILIZERS The results of the several comparisons that have been discussed in the preceding pages appear to substantiate the following statements with respect to the individual characteristics of the nitrogenous fer- tilizer materials manifested in this study: Nitrate of soda: Mtrogen from this material is completely available to the crop. However crop production fails to utilize much of the nitrates. The residue is quantitatively removed from the soil by leaching. Under normal rainfall conditions in Connecticut, ni- trate leachings during the growing season of a midsummer crop are insufficient to produce appreciable losses of nitrates from a sandy loam of fair loaminess and organic matter content. However, the earlier removals of larger amounts of nitrates by leaching than under other treatments indicate the possibilities of depletion below an amount sufficient to properly nourish the crop, when an unusually heavy rainfall in a single storm period is experienced. In June and July, 1938, nitrogen in the drainage water represented substantially all that was supplied in the fertilizer, and the crop obtained little more nitrogen than where none was added to the soil. Losses of calcium by leaching are at a minimum under this treat- ment, since nitrates and other acidic constituents in the drainage wa- Interrelations of I^itrogenous Fertilizers 319 ter are chiefly combined with sodium. However, crops are less able to obtain calcium, due to the reciprocal effects of the greater intake of potassium and sodium. A soil cropped to tobacco is made less acid by supplying nitrogen in this material, but to a lesser extent than indicated by tables in cur- rent use based on Pierre's computations. Annual cropping to tobacco, without green manure or cover crop, causes a considerable decline in soil organic matter and some loss in soil nitrogen, when this material is the sole source of nitrogen. Nitrate of potash: When all of the nitrogen is supplied from this source, an unnecessarily high potassium supply is provided. This extra potash has been reflected in the crop, in the leachings and in the accumulation of exchangeable potassium in the soil. Much smaller proportions of this element are leached than in case of the sodium constituent of the nitrate of soda treatment. There is an indication that nitrates are slightly less readily leached when supplied as ni- trate of potash. This material also tends toward decreasing the acid- ity of the soil. Soil changes indicate that this is chiefly due to in- creased exchangeable potassium in the soil. Nitrate of lime: Nitrates from this material are similarly dis- tributed between crop removal and leaching, as under the other two nitrate materials. Little of the extra calcium applied in this treat- ment is either removed by the crop or lost in the drainage water. However, the accumulation of this constituent in the exchangeable form fails to account for nearly all of the apparent net gain to the soil. The increased calcium in the crop has had some reciprocal ef- fect in causing small proportional amounts of the other bases, es- pecially magnesium. Sulfate of ammonia: This source of nitrogen has had pro- nounced effects upon both the soil and the crop. The acid effects have depleted the soil bases to a marked degree, chiefly through the leach- ing engendered by the sulfate constituent. Nitrate production in the soil is somewhat delayed, as witnessed by the lower proportionate leaching during the first three months after fertilizer application. Very heavy rains in early summer can cause considerable amounts of ammonia nitrogen to be washed through a sandy loam soil, at least to the depth of 18 inches. Not all of the nitrogen provided as sulfate of ammonia can be accounted for in the crop, in the leaching or in determined nitrogen residues in the soil. Tobacco crops supplied with nitrogen from this material have shown poor yields. The crop is unusually high in nitrogen, presum- ably due to absorption of ammonia nitrogen in addition to nitrates. The increased sulfur intake by the crop has tended to sustain the per- centages of non-volatile bases. However, the greater portion of the sulfate constituent is removed in the drainage water. The acid effects 320 Connecticut Experhnent Station Bulletin 458 of the treatment are also evidenced by increased manganese in the crop and leaching, and by the diminished bicarbonate content of the leachate and measureable amounts of aluminum dissolved from the soil. However, the net losses of the important soil bases (calcium, magnesium, potassium and sodium) fail to show acid effects of the magnitude usually ascribed to this material. This may be due to the relatively low initial base status of the soil employed in this experi- ment. Ammophos: This material, when used as the sole source of ni- trogen for the tobacco crop, supplies exceptional amounts of phos- phorus. However, in spite of the large application of this constitu- ent, no losses by leaching occurred. Only a few pounds could be ac- counted for in the increased phosphorus intake by the crop. The re- mainder produced an increase in the total phosphorus of the soil. Larger crops were obtained from this "ammonia nitrogen" source than in the case of sulfate of ammonia. However, apparent ammonia utilization by the crop and increased manganese content were also observed. The calcium content was adverserly affected, almost to the same degree as caused by the extra potassium in the nitrate of potash treatment. The base depletion of the soil caused by the combined effect of ammophos and the lessened basicity of other materials was similar in magnitude to that caused by sulfate of ammonia. The early leachings of nitrates from this material were unusually small. However, it must be considered that the crop was withdraw- ing more nitrogen during this period than in the case of sulfate of ammonia, due to the adverse effect of the latter. The total liberation of nitrogen during the year was incomplete. Some residue of nitro- gen remained in the soil. Urea: The results from this material are of special interest, since it is beginning to replace natural organic nitrogen sources in fer- tilizer mixtures. It appears to liberate a somewhat greater propor- tion of its nitrogen than do the vegetable derived organics, although not significantly more than from dried blood or tankage. A substan- tial proportion of its nitrogen is not accounted for in the crop or the drainage water losses. This is confirmed by a gain in soil nitrogen. However, the organic matter of the soil was less sustained than when cottonseed meal or castor pomace were used as the nitrogen source. Urea is definitely an acid-producing fertilizer, but to a much less pronounced degree than is sulfate of ammonia. The net acid effect of urea, in combination with other fertilizer constituents, was less than that shown by organic materials since these were used with smaller amounts of basic materials. The acid tendency of urea is in general agreement with current estimates by other investigations. Calurea: This material gave promise of being an important source of nitrogen when this experiment was started in 1929. How- ever, it has since disappeared from the American market. It is. es- Interrelations of Nitrogenous Fertilizers 321 sentially a mixture supplying four-fifths of its nitrogen as urea and one-fifth as nitrate of lime. The results obtained are consistent with this condition. The initial provision of some nitrate nitrogen has tended to cause earlier nitrate loss by leaching, greater nitrogen utili- zation by the crop and larger total nitrogen liberation during the year than when all of the nitrogen is supplied as urea. The increased cal- cium has also been evidenced in the crop. Cyanamid: This material was applied to the soil four weeks earlier than other treatments, in order to avoid initial toxic effects upon crop gTowth. Despite this advantage, the liberation to the soil as nitrates appears to be unusually slow. The crop was able to ob- tain normal amounts of nitrogen, comparable in this respect to most other materials with the exception of the nitrates. Some of this ni- trogen intake seems to have been in the form of ammonia. The unusual amounts of calcium provided in this treatment are reflected to some extent in the greater proportion of calcium in the crop. The loss of this constituent by leaching has not been corres- pondingly affected. The net result has produced a great increase in the calcium content of the soil, sufficient to practically saturate the base exchange capacit}^, with a considerable net gain in the base status in excess of amounts thus measured. Cottonseed meal : This is the organic nitrogen source most gen- erally used for tobacco in the Connecticut Valley. It is also used as a constituent of mixed fertilizers for other crops. The amount of ni- trogen applied in this experiment would be considered excessive for most crops. However, it is the common rate for tobacco in this lo- cality. In this experiment the crop has been able to utilize less than 40 percent of the nitrogen added in the treatment. However, since the total nitrogen liberation under cottonseed meal has been but T2.5 per- cent of the aj^plication, the crop actually obtained approximately 51 percent of the amount of nitrogen becoming available in the soil dur- ing the 3^ear. The percentage of nitrogen in tobacco was consistently lower than under any of the inorganic treatments, but was adequate for normal growth. In reasonably wet seasons, when some leaching of nitrates from the root zone occurred, the nitrogen obtainable by the plant was on the verge of insufficiency^ The leaching of 78 pounds of nitrogen per acre produced by the excessive summer rain- fall in 1938 left the soil so depleted that the crop could obtain but 45 pounds. This and other evidence leads to the conclusion that, al- though 200 pounds of nitrogen are applied and a small additional amount must be obtainable from the soil itself, only about 125 pounds of available nitrogen is developed in the soil during the growing sea- son of the tobacco crop under normal fertilizer practice. Unless un- usually heavy rains materially deplete the soil below this level, the crop can obtain an adequate but not excessive amount under these con- ditions. 322 Connecticut Experiment Station Bulletin 458 The total availability of cottonseed meal is definitely less than that of urea, dried blood or tankage, and apparently slightly less than castor pomace and linseed meal. The rate of availability is sim- ilar to other high-grade organics and is not materially different from urea. Cottonseed meal is somewhat acid in its effects upon the soil. The currently used estimate that 200 pounds of limestone would be required to counteract the acidity of a ton of cottonseed meal of aver- age composition is supported by the results of this experiment. Unless calcium is supplied from other sources, such as gypsum or limestone, as was not done in this experiment, a tobacco fertilizer in the "2-1-2" ratio, formulated from cottonseed meal, precipitated bone and the usual materials to supply potash and magnesia, favors a def- inite depletion of the available calcium supply of the soil. Magne- sium is more readily available to the plant under such conditions, but the calcium intake by the crop may become critically low, especially from the standpoint of quality production. The use of cottonseed meal as the source of nitrogen causes some increase in the residual nitrogen of the soil, and tends to maintain soil organic matter, to a significantly greater degree than when nitro- gen is derived from inorganic materials. However, unless green manure or cover crops are grown, soil organic matter is not fully maintained. Castor pomace: The results from this material have been sim- ilar to cottonseed meal. However, it appears to liberate somewhat more of its nitrogen at a slightly greater initial rate. The acidity and base relationships of castor pomace are also^ much like those for cottonseed meal. Castor pomace caused an unexpectedly high residual effect upon soil organic matter. This has been repeatedly checked on several soil samples with consistent results. This could be due to the possibility that castor pomace is essentially a mixture of two types of material: one of high nitrogen content and rapid availability producing little 'Organic residue; the other of low organic nitrogen content and high in lignin or other substance quite resistant to decay. This feature is to be studied more fully. If confirmed and explained, such a char- acteristic of castor pomace would be an important consideration in its use. Linseed meal: The nitrogen availability of this material is in- termediate between cottonseed meal and castor pomace. It does not exhibit the residual effect on soil organic matter noted for the latter. Its effects upon soil acidity and base inter-relationships are similar to the other vegetable-derived organics. None of the data discloses any explanation for the belief prevalent among tobacco growers that this material imparts special quality characteristics. Fish meal: Used in this experiment as the sole source of nitro- gen, this material supplied more than the normal amounts of phos- Inte7Telations of Nitrogenous Fertilizers 323 phoriis. This was very sli<2;htly reflected in the crop. However, the increased phosphorus residue in the soil was of a measureable ex- tent. It is of interest to note that the apj^arent availability of this residual phosphorus appeared to be unusually hi