BULLETIN 308 JUNE 1958 BULLETN 308REPRINTED SOURCES a NITROGEN o COTTON ad CORN p S Ur FORI THE to'b ADVANCEMENT~ \~ tUV AND ARTS 110 g X l , AGRICULTURAL of M~e EXPERIMENT STATION ALABAMA POLYTECHNIC INSTITUTE Auburn, Alabama E. V. Smith, Director CONTENTS Page DESCRIPTION OF FERTILIZER MATERIALS THAT CONTAIN NITROGEN GENERAL DESCRIPTION OF FIELD EXPERIMENTS EXPERIMENTS WITH SEVERAL SOURCES OF NITROGEN, 1929-45 RESULTS ON COTTON __-__ 5 7 9 9 Sand Mountain Substation, Hartsells Fine Sandy Loam Wiregrass Substation, Norfolk Fine Sandy Loam Tennessee Valley Substation, Decatur Clay Loam RESULTS ON CORN .--------------- 9 13 18 17 Sand Mountain Substation, Hartsells Fine Sandy Loam Wiregrass Substation, Norfolk Fine Sandy Loam Tennessee Valley Substation, Decatur Clay Loam EXPERIMENTS WITH AMMONIUM SULFATE AND SODIUM NITRATE, 1929-45 RESULTS ON COTTON ---- 17 17 17 23 23 23 23 23 26 26 Wiregrass Substation, Norfolk Fine Sandy Loam Monroeville Experiment Field, Magnolia Fine Sandy Loam Sand Mountain Substation, Hartsells Fine Sandy Loam Tennessee Valley Substation, Decatur Clay Loam RESULTS ON CORN -------__ Wiregrass Substation, Norfolk Fine Sandy Loam Monroeville Experiment Field, Magnolia Fine Sandy Loam Sand Mountain Substation, Hartsells Fine Sandy Loam Tennessee Valley Substation, Decatur Clay Loam EXPERIMENTS WITH AMMONIUM -SULFATE, SODIUM NITRATE, AND AMMONIUM NITRATE, 1946-55 RESULTS ON COTTON 26 26 29 29 29 80 Wiregrass Substation, Norfolk Fine Sandy Loam Monroeville Experiment Field, Magnolia Fine Sandy Loam Sand Mountain Substation, Hartsells Fine Sandy Loam Tennessee Valley Substation, Decatur Clay Loam RESULTS ON CORN 30 30 30 33 35 35 Wiregrass Substation, Norfolk Fine Sandy Loam Monroeville Experiment Field, Magnolia Fine Sandy Loam -- 35 Sand Mountain Substation, Hartsells Fine Sandy Loam ----35 Tennessee Valley Substation, Decatur Clay Loam 35 OTHER EXPERIMENTS WITH SOURCES OF NITROGEN ON COTTON SOURCES OF NITROGEN ON UNLIMED AND LIMED CHESTERFIELD SANDY LOAM AT AUBURN, 1928-41 39 39 SODIUM NITRATE AND AMMONIUM SULFATE WITH AND WITHOUT LIME ON CHESTERFIELD SANDY LOAM, AUBURN, 1925-55 ---39 RATIOS OF ORGANIC TO INORGANIC NITROGEN IN FETILIZERS FOR COTTON ON DECATUR CLAY LOAM, ALEXANDRIA EXPERIMENT FIELD, 1929-43 41 43 52 53 GENERAL DISCUSSION SUMMARY -45 ACKNOWLEDGEMENT LITERATURE CITED _... ..----.............. FIRST PRINTING 31/2M, NOVEMBER 1957 SECOND PRINTING 3M, JUNE 1958 SOURCES of NITROGEN o COTTON ad CORN i 4eaama C. E. SCARSBROOK, Associate Soil Chemist J. T. COPE, Jr., Associate Agronomist ITROGEN MUST BE applied to Alabama soils for economic proN duction of all non-leguminous crops. Although these soils release some available nitrogen each season from their organic nitrogen reserve, the amount released is too small for satisfactory crop production. Additional nitrogen, therefore, must be obtained from other sources. It may be added to the soil by leguminous plants, plant residues, animal residues, or by commercial fertilizers. Only nitrogen from commercial fertilizers is considered in this report. Plants can utilize several forms of nitrogen, but the ammonia and nitrate forms are of primary importance. The ammonia form may be attached to soil particles, and while thus attached it is not subject to appreciable leaching. Nitrate is not held to soil particles and is subject to leaching unless held by incorporation into organic matter by soil organisms. Ammonia is rapidly converted to the more easily leached nitrate under most Alabama growing conditions. Most plants absorb both nitrate and ammonia during all stages of growth, but the relative proportion of each may vary during the life of the plant (1). Ammonia is rapidly converted to nitrate when the soil is warm, moist, well aerated, and the pH is not too low. This conversion, called nitrification, is a biological process of soil organisms. Most soils contain an ample supply of the necessary organisms. Under favorable conditions, nitrification begins soon after application of ammonia and it is largely com- ALABAMA AGRICULTURAL EXPERIMENT STATION plete wxithini a fexx' daxys to aite fxx\ weeks. Thie rate of nitrificatioun is (deereased in wxin ter doue to hloxer silitem peraturles, but in no) part of Alaa (10 soil temp[eratulres remain low enough to prexv(ent niitrification for lonig periods. Thie (lenunits aceoli panx in g niitrogen in some fert ilizers max hax c anI effeet on crop p)roduiction Cahlcium ciitrate [C(0 NO a7 aninoiiim nitrate pinls liiiistolie [I 11NO 1 -~ (Xi( () and calcium c aniamid [( a(CN ) xvill produce a y ieldl responise in a(dditioni to that fromi nitrogen xx1c heialeitilo is deficienit. Crops onl sul I r-deficient soils lnam re sponid to ammvoiimi sulfate L(N itI Sod] b~ecause of the sulfur wxhielh it conitains. Thie sodiimi in sodiiii nitrate [NAX():;1, though not an essentdial e'lemlent, has lcenl found( 1)eneficial for soniie crops. Thie amnli li phosphates supljy txxo nmajor elemnts, nitro aeniand phosphorus, in the same miaterial. Both iiitrogei and~ potassinii are supplied lIm potassinll niitrate [h1\0:j. ( n the otlherhlalidl aiilixdrous ammiinlia [Nil], alioiioliiuli niitrlit( LNII NO:, and ureca [COANI) * airc of xvalue solecx for the rnitrog'ii tlhex conltaini. T[le niaturial o1ganiics may con tain niiimi elemnie ts of, xaloe to crops. Nitrogen fertilizers ii ax make the soil miore aeidl, l(ss acidl, or The dex eloplielt of aeihitxv froimi no0 (e1fect on aeidhit\ aliiiioliia fertilizers is largelx a result of niitrification xxhei el\ itli aunoi)1ia is chiairiedl to nitrate xx a release of acid into tlhe soil. liax c r 2. V A This cotton is growing an Hartsells fine sandy loom where acidifying nitrogen fertilizers were used without lime from 1929 until 1956. Crabgrass severely infests these acid plots when cultivation is stopped. SOURCES of NITROGEN 5 Some nitrogen fertilizers leave an excess of a base (such as calcium or sodium) in the soil, which reduces soil acidity. DESCRIPTION or FERTILIZER MATERIALS THAT CONTAIN NITROGEN There are thousands of compounds that contain nitrogen, but only a few can be produced economically for use as fertilizer. The materials listed and discussed here include those used in experiments reported in this publication, as well as some others that have received considerable distribution in commercial trade. Ammonium nitrate [NH 4NO 3] is produced by combining ammonia with nitric acid. The resulting product is white in color. It contains 32.5 to 33.5 per cent nitrogen, with equal parts of ammonia and nitrate nitrogen. The fertilizer grade is in the form of crystals or pellets that have been coated with a conditioner to reduce caking. It is acid-forming and requires 60 pounds of limestone to neutralize 100 pounds of material. Ammonium nitrate and limestone are sometimes mixed to form a nonacid-forming product containing 16 to 20.5 per cent nitrogen. This product has been marketed under various names. It contains only enough limestone to neutralize the acidity produced by the ammonium nitrate. Ammonium phosphates are manufactured by combining ammonia and phosphoric acid. There are two principal forms of this fertilizer, monoammonium phosphate [NH 4H2PO 4] and diammonium phosphate [(NH 4) 2HP0 4 ]. Monoammonium phosphate contains 11 per cent nitrogen and 48 per cent P20 5, and diammonium phosphate contains 21 per cent nitrogen and 54 per cent P2 0 5. Both are acid-forming. Ammonium sulfate [(NH 4) 280 4] is produced by the reaction of ammonia with sulfuric acid. Large quantities have been produced using by-product ammonia from coke ovens. More recently an increasing amount has been made by reacting synthetic ammonia with sulfuric acid. The nitrogen content is 20.5 per cent and the color may vary from white to yellow to gray. Ammonium sulfate is acid-forming and requires about 110 pounds of limestone to neutralize 100 pounds of material. Anhydrous ammonia [NH 3] is stored as a liquid under pressure. It has a gauge pressure of 75 p.s.i. at 50 ° F. and 197 p.s.i. 6 ALABAMA AGRICULTURAL EXPERIMENT STATION at 100 ° F. The nitrogen content is 82 per cent. When released at atmospheric pressure, it forms a colorless gas that is extremely irritating to the nose, eyes, skin, and lungs. It should be released in the soil deep enough so that soil above the release point will seal in the gas. The reaction of ammonia with soil constituents is rapid; the initial product is ammonium hydroxide with a resulting alkaline reaction. This alkaline reaction is only temporary, and as a result of bacterial action, the alkaline reaction disappears and the end result is an increase in soil acidity. One hundred pounds of anhydrous ammonia requires about 148 pounds of calcium carbonate for neutralization. Nitrogen solutions of several different kinds are produced for fertilizer. These are water solutions of various combinations of ammonia, urea, and ammonium nitrate. The nitrogen content ranges from 21 to 53 per cent. They may have no pressure or a relatively high pressure depending upon the content of free ammonia. Pressure solutions are applied below the soil surface to seal in the gas, whereas non-pressure solutions may be applied on top of the soil. Calcium cyanamid [CaCN 2] is manufactured from coke, limestone, and atmospheric nitrogen. It was one of the earlier products of the synthetic fixation of atmospheric nitrogen. It is produced in powdered, granulated, and pelleted forms, and contains 20 to 22 per cent nitrogen. It produces an alkaline reaction in the soil equivalent to 63 pounds of limestone per 100 pounds of cyanamid. The commercial product is black because of the presence of free carbon. Calcium cyanamid is toxic on direct contact with seeds and seedlings. For row crops it should be applied at least one week prior to planting. Calcium nitrate [Ca(NO3) 2] is made by reacting limestone with nitric acid. The resulting product is a white material that readily absorbs moisture from the atmosphere. The tendency to become wet and soggy has been reduced by mixing with limestone or by coating the particles. The fertilizer must be used shortly after the moisture-resistant bags are opened. The fertilizer grade contains enough ammonium nitrate to bring the nitrogen percentage up to 15.5 It has a slight neutralizing effect on acid soils. It has been produced as fertilizer in Europe, but has not been manufactured on a large scale in this country. SOURCES of NITROGEN 7 Cottonseed meal is a by-product of the cottonseed oil industry. It is yellowish brown in color and contains 6 to 9 per cent nitrogen. Because of demand for the product as feed, it is now seldom used as a fertilizer. Potassium nitrate [KNO 3] is found in a few natural deposits or is manufactured by reacting nitric acid with caustic potash or potassium carbonate. It has less tendency to absorb moisture than most other forms of nitrate. It contains about 13 per cent nitrogen and 43 per cent potash and has a slight neutralizing effect on acid soils. Sodium nitrate [NaNO 3] has two important sources. One is the refined product from deposits in the desert plateaus of Chile. The other is made by reacting nitric acid with sodium carbonate. Both products contains about 16 per cent nitrogen. Sodium nitrate is white in color and is marketed in pellet form. It has a slight neutralizing effect on acid soils. Urea [CO(NH 2) 2] is a synthetic product produced by reacting ammonia and carbon dioxide under high pressure. The fertilizer material is white or greenish and is usually marketed in pellet form. It contains 42 to 45 per cent nitrogen. Nitrogen in urea hydrolyzes to ammonium form of nitrogen in the soil. The ammonia is changed to nitrate, resulting in increased acidity. Some of the important characteristics of the various nitrogen materials discussed are listed in Table 1. GENERAL DESCRIPTION OF FIELD EXPERIMENTS The Agricultural Experiment Station of the Alabama Polytechnic Institute has done a large amount of research on sources of nitrogen. This work dates back to 1911 when the sources of nitrogen were the natural organics, ammonium sulfate, calcium cyanamid, and sodium nitrate. This early work is covered in publications issued prior to 1933. Pierre (2, 3) reported the effects of various nitrogenous fertilizers on soil reaction and determined the equivalent acidity and basicity of the different sources of nitrogen, Table 1. Tidmore and Williamson (4) reported results from many field and laboratory experiments conducted prior to 1932 in a comprehensive bulletin. Volk and Tidmore (5) published data on the effect of different nitrogen sources on soil reaction, exchangeable ions, and yields of crops. The present 8 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 1. NUTRIENT CONTENT AND EQUIVALENT ACIDITY OR BASICITY OF CERTAIN SOURCES OF NITROGEN Nutrient content Treatment Treatme nutrients NitrogenOther Pct. Ammonium nitrate_ 33.5 Equivalent acidity or basicity-lb. CaCO 31 Per pound of nitrogen Acidity Basicity Lb. Lb. 1.80 Per 100 pounds of product Acidity Lb. 60 Basicity Lb. Pct. Ammonium nitrate_ limestone____________ Ammonium sulfate_ 20.5 20.5 16 Ca 23 S 0 5.35 0 0 110 0 Anhydrous ammonia ___________ 82.0 Calcium cyanamid._ 22.0 Calcium nitrate _____ 15.5 Cottonseed meal-....to 9 6 Diammonium phosphate ......... 21.0 Monoammonium phosphate---------11.0 Potassium nitrate---. 13.0 Sodium nitrate-------- 16.0 Urea 45.0 ____ 38 Ca 44 Ca 2 P 205 2 K20 54 P 20 5 1.80 2.85 1.35 1.45 3.50 5.35 2.00 1.80 1.80 148 63 21 10 74 59 26 29 81 48 P 20 5 43 K20 26 Na ___ ' Determined by method of Pierre (2). report covers the results of the continuation of some experiments included in the previously mentioned publications plus work that was started subsequently. Long-term experiments on sources of nitrogen for cotton and corn at six locations are reported here. The soil types and their locations are: Decatur clay loam at the Tennessee Valley Substation and Alexandria Experiment Field, Hartsells fine sandy loam at the Sand Mountain Substation, Norfolk fine sandy loam at-the Wiregrass Substation, Magnolia fine sandy loam at the Monroeville Experiment Field, and Chesterfield sandy loam at the Main Station at Auburn. All except those on the Main Station were conducted on tiers consisting of 34 1/30-acre plots. Plots 1A to 17A were laid out from left to right, and duplicate plots 1B to 17B from right to left. Plots 1, 5, 9, 13, and 17 in each duplicate were check plots. Fertilizer and lime treatments, and methods of application are given in the introductions to the various experiments and as footnotes to the tables. Pre-planting fertilizers were applied in a furrow and bedded on before planting. Sidedress applications were applied beside the row 35 to 40 days after planting. SOURCES of NITROGEN 9 In experiments that involved both cotton and corn, these crops were in a 2-year rotation. Both crops were planted each year on alternate tiers. Crop residues were left on the plots in all experiments. Since the cost of nitrogen from the various sources and prices received by farmers for cotton and corn vary from year to year, relative returns per unit cost of nitrogen are not included in this publication. Returns may be calculated from the yield data presented, using prices that prevail at any time. EXPERIMENTS WITH SEVERAL SOURCES OF NITROGEN, 1929-45 Sources of nitrogen experiments were conducted at the Sand Mountain, Tennessee Valley, and Wiregrass substations using a cotton-corn rotation. Sources used were ammonium nitrate, sodium nitrate, ammonium sulfate, urea, calcium nitrate, diammonium phosphate, cottonseed meal, and calcium cyanamid. Both limed and unlimed tiers were included at the Tennessee Valley and Wiregrass substations. Limed tiers received 2,250 pounds of calcitic limestone per acre when the experiments were begun and sufficient dolomitic limestone annually mixed with the fertilizer to neutralize the acid-forming sources of nitrogen. The limed tiers were adjacent to the unlimed tiers. Cotton received 86 pounds of N, 48 pounds of P2 05, and 24 pounds of K20 per acre annually. Corn received 86 pounds of N, 24 pounds of P2 0 5, and 12 pounds of K20 per acre annually. Nitrogen, phosphate, and potash treatments were the same on both limed and unlimed tiers. Sidedressed plots received one-fourth of the N at planting and three-fourths as a sidedressing. Relative yield increases were calculated by using a value of 100 per cent for the yield increase from a split application of sodium nitrate. This source was selected as a base since it was used in all tests. RESULTS ON COTTON Sand Mountain Substation, Hartsells Fine Sandy Loam UNLIMED (TABLE 2). Average yields at this location for the 1929-45 period show little or no differences between sodium nitrate, cottonseed meal, urea, and calcium nitrate. These sources r TABLE 2. COTTON YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS IN A COTTON-CORN HARTSELLS FINE SANDY LOAM, SAND MOUNTAIN SUBSTATION, 1929-45 ROTATION, Method of Nitrogen application Seed cotton yield increases from different nitrogen sources by periods' 1929-45 average 1942-45 1934-37 1938-41 1929-33 Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase pH in O .TI- Lb. None ----------Ammonium nitrate Sodium nitrate Pct. -86 Lb. (513) 734 Lb. (565) 907 + -------limestone_____- Sidedress4 ________. (624) 598 Lb. (575) 723 928 886 Pct. 78 100 95 Lb. (572) 732 866 878 Pct. 85 100 101 5.5 5.0 r Yic) 694 100 820 Sidecress4 -------------------------1,063 1,055 754 109 847 -------------------------------649 699 731 519 651 539 Under Sodium nitrate Sidedress4 Ammonium sulfate____________________________ Under Ammonium sulfate 93 101 105 75 94 78 556 785 781 380 825 672 718 971 935 441 1,025 868 309 339 789 763' 235 902 610 33 37 85 82 25 97 66 563 587 804 798 401 839 664 65 68 93 92 46 97 77 4.8 5.1 5.7 4.5 5.2 8rr --------------------------- 702 671 97 614 Sidedress4 Sidedress4 Under Under Under Urea--------------_----------- 3I3-I C C nitrate ----------------phosphate---------Cottonseed meal ---------------Calcium cyanamid--------------Calcium Diammonium m x z P 20 5 from superphosphate except the diammonium phosphate plots, plots except checks received 36 lb. of N; 48 lb. 1All P2 05; and 24 lb. of Kf0 from muriate of potash. which received 93 lb. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. of of m 1929 was pH 'The original plotsin received / 5.7. N 4Sidedressed of at planting and / as sidedressing. 0 ' Changed to urea in 1942. z SOURCES of NITROGEN r~4 ~ / ~ - ,y '] 3",d "e.. < a yC W ' t'p v r -^ ' A Cotton at right is nitrogen deficient, whereas rows at left received ample nitrogen. The soil is Magn~olia fine sandy loam. XX lcrcas alliiiii occuipi'd iiiil iiitrato phois liiiicsti c and calciiiii cx naiid ii tc'rnliat(' p)osition s. The lower eiids fiomi amiiino ci linki oil XX ('ic soil JAL1 assoiciatedl Xithi tiheir Siincc all ('\cept thi( aiciditx torii (liaiiiiiiliii i'occiN ((I calciiiii a suilfate inithoc as iiiclicatcd Imxthir cflcct phiosphat' plots of, sil)lp lii)5jsliat. a pjart sfin lficiciicx oil this saiikl sil. ii 'Ilic ci umllilatki c effect of thic sioiirccs is ihest Inciasi-e ir(Il thc x icitis ill thc last period. 1942-45. This periodl xwill 1e UcI sed tiiroliglaout thc dliscus1ion as a incasi ic of thic loiig-t iluc ('flect f roni thic soiii'cs. Sodiln ni iitrate aiid cottoi isccd imcal xwere supcrli to all otlier -oooirccs. -1' differci'iecs iii X icid 1 ctxX cci thI isc andiit(ailii oiiiii phosphaite and~ aimmioniiuiml suilfate XXcac nitili 1(rceatcr thaii had beeni thie case ill tihe first period. fich oliox soiirccs that miainitainecd the pnil nicar thec oiinal icx ci X\ ('c calcii ntX cai ait andi sodiumii nitrate. Plots that rcccix'd hme (rced Apl thic nil to 4.5, wiichl iii ! is f&ar bl)ioXX op~tiiii lil iiti'ogci fori cottoii prodictioil thre't-fouirths of th(' as si(1('(lr(ssil dg(1i nt Appar' tIX leachii as iiot a sious piidiciim oil this soil. TABLE 3. COTTON YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS IN A NORFOLK FINE SANDY LOAM, SUBSTATION, 1930-40 WIREGRASS COTTON-CORN ROTATION, Nitrogen source' Method of application Seed cotton yield increases from different nitrogen sources by periods2 1938-40 1930-40 average 1930-33 1934-37 Yield Relative Yield Yield Relative Yield Relative increase increase increase increase increase increase increase pH in 19463 None -- - - - - - - - - Ammonium nitrate limestone Sodium nitrate Sodium nitrate--------. Ammonium Ammonium Lb. (793) Sidedress' Pet. Lb. (774) 700 813 709 761 671 773 835 426 791 741 Lb. (602) 868 858 682 768 538 817 808 289 905 832 Pet. - Lb. (734) 612 691 586 652 546 682 710 317 684 643 Pct. 5.2 89 100 85 94 79 99 103 46 99 93 5.1 5.4 5.1 5.3 C + 332 445 392 4 Sidecdress Under Sidedress 4 75 100 88 103 96 110 115 51 92 91 101 100 79 90 63 95 94 34 105 97 sulfate-----_ sulfate-----_ --------- 457 Under Sidedress Sidedress Under Under Under 4 4 426 489 513 228 410 403 Urea -- - - - - - - - - - - - - - - Calcium nitrate Diammonium phosphate- Cottonseed meal-------- 5.4 5.7 m x z -a Calcium cyanamid .----- 'All plots except checks received 36 lb. of N: 48 lb. 2 from superphosphate except the diammonium phosphate plots, PO,; and 24 lb. of K2 0 from muriate of potash. which received 93 lb. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. of of P0 as m 'Th -a original pH in 1929 was 5.7. Sidedressed plots received 4 of N at planting and sideressing. 0 z SOURCES of NITROGEN 13 Wiregrass Substation, Norfolk Fine Sandy Loam UNLIMED (TABLE 3). Similar yields were obtained from all sources with the exception of diammonium phosphate, which was inferior throughout the period. The lower yields from this material were probably the result of a lack of sulfur and of increased soil acidity. The sandy soils of this area do not contain much sulfur so that a deficiency may develop when no sulfur is added for long periods of time. This experiment was conducted for only 11 years; therefore, the cumulative effects of acid-forming sources were not as extreme as those after 17 years at Sand Mountain. Low yields, however, were produced during all periods from diammonium phosphate. Method of application was important at the Wiregrass Substation. In the 11-year averages, yields were increased about 100 pounds of seed cotton from split applications of both sodium nitrate and ammonium sulfate. LIMED (TABLE 4). The sources produced similar yields except for diammonium phosphate, which resulted in low yields throughout all periods of the experiment. All treatments where pH effects were determined maintained pH about constant except calcium cyanamid, which increased soil pH from 5.8 to 6.1. With liming to counteract acidity development, ammonium sulfate compared favorably with nonacidforming sources. There was an advantage from splitting the application of nitrogen, especially with ammonium sulfate. Tennessee Valley Substation, Decatur Clay Loam UNLIMED (TABLE 5). Yield responses to nitrogen on this soil were less than at the other locations, especially in the first few years of the experiment. There were no large differences between sources for the 1929-45 period. The acid-forming sources caused no change in pH on this red clay loam soil, which has an exchange capacity of about 12 m.e. per 100 gin. During the 1942-45 period, cottonseed meal, sodium nitrate, and calcium cyanamid produced the highest yields. Ammonium sulfate, urea, diammonium phosphate, and calcium nitrate were less productive. Ammonium nitrate plus limestone was intermediate. TABLE 4. COTTON YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON LIMED' PLOTS IN A COTTON-CORN ROTATION, NORFOLK FINE SANDY LOAM, SUBSTATION, 1930-40 WIREGRASS Nitrogen source' Method of application 3 Seed cotton yield increases from different nitrogen sources by periods 1930-40 average 1938-40 1930-33 1934-37 Relative Yield Yield Relative Yield Yield Relative increase increase increase increase increase increase increase pH in 19464 N one-- - - - - - - - Ammonium nitrate + limestone Sidedress Under Sidedress' Under Sidedress' Sidedress' Under Under Under 5 Lb. (992) 332 431 360 442 356 409 434 261 391 374 Pct. Lb. (1,067) 485 672 651 674 608 590 675 564 652 644 Lb. (799) 760 775 723 863 570 Pct. Lb. (967) 504 612 565 641 506 562 606 451 607 568 Pct. 5.7 82 100 92 105 83 92 99 74 99 93 5.8 0 77 100 84 103 83 95 101 61 91 87 98 100 93 111 74 94 96 71 108 94 Sodium nitrate Sodium nitrate--------Ammonium sulfate----Ammonium sulfate-----. Urea -- - - - - - - - - - - - - - - Calcium nitrate-------Diammonium phosphate Cottonseed meal Sidedress' 5.7 5.8 C -I r- 727 742 553 836 727 C ------- 5.7 5.7 6.1 r- m m m Calcium cyanamid-----1 Mu z All plots limed with 2,250 lb. of calcitic lime in 1930. Sufficient dolomitic lmestone mixed with fertilizer each year to neutralize acid-forming sources of nitrogen. P2 05 from superphosphate except the diammonium phosphate plots, which 2 All plots except checks received 36 lb. of N; 48 lb. received 93 lb. of P2O 5; and 24 lbs. of K2O from muriate of potash. 'Check yields (in italcs) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. of 'Th 5Sidedressed plots received original pH in 1930 was 5.8. / of N at planting and / as sidedressing. 0 z O 0 C TABLE 5. COTTON YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS IN A DECATUR CLAY LOAM, TENNESSEE VALLEY SUBSTATION, 1929-45 COTTON-CORN ROTATION, n II O Nitrogen Seed cotton yield increases from different nitrogen sources by periods2 1929-45 average 1942-45 1929-33 1934-37 1938-41 Method of application Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase Lb. Pct. 64 100 100 65 63 73 76 68 70 55 Lb. (1,075) 427 369 393 375 298 388 355 351 277 292 Lb. (1,078) 850 774 705 844 707 815 851 740 704 787 Lb. (1,088) 399 475 347 304 302 337 3545 343 496 437 84 100 73 64 64 71 75 72 104 92 Pct. Lb. (1,127) 445 460 420 410 358 421 427 892 403 401 97 100 91 89 78 91 93 85 88 87 Pct. (1,240) Sidedress Sidedress 4 pH in m z 5.6 None _______-------------------------Ammonium nitrate - limestone-----Sodium nitrate Sodium nitrate Ammonium sulfate________________............ -. Ammonium sulfate _____________.........Urea---------Calcium nitrate-................ 173 271 271 177 171 199 205 185 190 150 4 Under 4 Sidedress Under Sidedress' Sidedress 4 5.8 5.5 5.7 5.5 5.7 5.8 Diammonium phosphate......... Under Under Cottonseed meal-................ Calcium cyanamid-.............. Under 'All plots except checks received 86 lb. of N; 48 lb. of P20 5 from superphosphate except the diammonium phosphate plots, which received 93 lb. of P2O; and 24 lb. of K 20 from muriate of potash. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. SThe original pH in 1929 was 5.7. 4 Sidedressed plots received of N at planting and 3/ as sidedressing. 5 Changed to urea in 1942. /4 NI TABLE 6. COTTON YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON LIMED PLOTS IN A COTTON-CORN ROTATION, CLAY LOAM, TENNESSEE VALLEY SUBSTATION, 1929-45 1 DECATUR Seed cotton yield increases from different nitrogen sources by periods 3 Method of Nitrogensoureapplication 2 1929-45 average 1942-45 1984-37 1938-41 1929-83 Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase Lb. Pct. Lb. Pct. Lb. Lb. Pct. Lb. (1,287) __ 80 100 97 83 76 90 110 92 83 pH in None -------------------------------------Ammonium nitrate + limestone-Sodium nitrate -------------------------Sodium nitrate---------------------------------------------------Ammonium sulfate Ammonium sulfate --------------------------------------------------------Urea Calcium nitrate Cottonseed meal - (1,164) 319 366 345 322 335 340 314 (1,165) 780 732 641 725 679 786 716 692 584 (1,084) 419 438 879 315 437 808 8116 840 447 (1,182) 96 100 87 72 100 70 71 78 102 6.0 96 100 90 88 91 93 91 87 85 r- Sidedress' Sidedress Under Sidedress' Under Sidedress' Sidedress' Under Under 5 190 237 231 196 180 214 261 218 197 413 431 889 878 894 400 392 v yI6.1 5.9 6.0 6.0 6.1 C I Diammonium phosphate------------------ 283 280 874 866 C r I-l Calcium cyanamid-------------- Under 217 92 843 654 401 92 898 91 6.8 m x Ii m 1All plots limed with 2,250 lb. calcitic lime in 1929. Sufficient dolomitic limestone mixed with fertilizer each year to neutralize acid-forming sources of nitrogen. 2 All plots except checks received 86 lb. of N; 48 lb. of P20 5 from superphosphate except the diammonium phosphate plots, which received 98 lb. of P20; and 24 lb. of K2O from muriate of potash. 3 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. original pH in 1929 was 5.8. as Sidedressed plots received 1/4 of N at planting and 3/4 sidedressing. 6 Changed to urea in 1942. z -I -L 'The z SOURCES of NITROGEN 17 LIMED (TABLE 6). The increases in cotton yields from the nitrogen sources ranged from 366 to 431 pounds of seed cotton. Differences in yields were much less than those obtained at most other locations. Comparison of yields from the limed and unlimed tiers at this location shows very little difference due to lime. Lime tended to make the acid-forming nitrogen sources compare more favorably with the others than was the case on the unlimed tiers. RESULTS ON CORN Sand Mountain Substation, Hartsells Fine Sandy Loam UNLIMED (TABLE 7). The list of yields obtained in all periods shows ammonium sulfate applied under, diammonium phosphate, cottonseed meal, and calcium cyanamid at the bottom. The response of corn to 36 pounds of nitrogen was large at this location. The best sources increased the yield as much as 29 bushels per acre (17-year average). This yield increase is more than three-fourths of a bushel of corn per pound of nitrogen applied. Wiregrass Substation, Norfolk Fine Sandy Loam UNLIMED (TABLE 8). Yield differences in this experiment were not as large as those at the Sand Mountain Substation. In general, differences between sources were small. Cottonseed meal and cyanamid produced the lowest yields, as was found at Sand Mountain. These two sources were not nearly as effective on corn as they were on cotton. LIMED (TABLE 9). Differences between sources at this location were small, but yield levels were so low that large differences could not be expected. Tennessee Valley Substation, Decatur Clay Loam UNLIMED (TABLE 10). Yields from all sources at this location were about equal. LIMED (TABLE 11). Differences in corn yield between sources of nitrogen were small. Lowest yields were produced by diammonium phosphate, cottonseed meal, and cyanamid. TABLE 7. CORN YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS IN A HARTSELLS FINE SANDY LOAM, SAND MOUNTAIN SUBSTATION, 1929-45 COTTON-CORN ROTATION, Nitrogen nsource' Method of application 2 Corn yield increases from different nitrogen sources by periods 1942-45 1929-45 average 1984-37 1938-41 1929-33 Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase Bu. None --------------------------------- Pct. -75 100 86 86 Bu. (5.5) 29.3 81.3 28.4 24.8 30.7 24.9 Bu. (3.9) 31.7 32.6 28.5 28.4 32.2 27.3 (9.6) Sidedress 3 Bu. (5.7) 26.8 29.8 29.8 24.0 22.7 Pct. Bu. (6.4) 26.5 29.8 27.1 24.9 22.5 Pct. -- Ammonium nitrate + limestone_______________________________ Sodium nitrate_____________________________ 19.9 26.5 22.9 22.9 90 100 100 81 76 89 100 91 84 76 c Sidedress3 Under Sodium nitrate_____________________________ Ammonium sulfate_________________----Sidedress3 Ammonium sulfate 25.4 75 22.9 19.8 ----------------------Under 25.2 22.3 Calcium nitrate-___________________________ Sidedress3 95 84 27.01 26.2 91 88 28.6 25.0 96 84X Urea ----------------------Diammonium phosphate_______ Cottonseed meal_____________ Calcium cyanamid Sidedress3 Under Under Under 18.6 12.9 16.2 70 49 61 20.8 16.8 23.8 24.6 19.7 22.3 23.9 19.6 18.7 80 66 63 21.8 17.0 20.0 73 57 67 ----------- " m ' All plots except checks received 36 lb. of N; 24 lb. of P 205 except the diammonium phosphate plots, which received 121 lb. of P2O5; and 12 lb of K20 from muriate of potash. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility M .-. - changes uniformly from one check plot to the next. 4Sidedressed plots received 1/4 of N at planting and 3/ as sidedressing. Changed to urea in 1942. 0 Z 0 C L~O TABLE 8. CORN YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS IN A COTTON-CORN ROTATION, NORFOLK FINE SANDY LOAM, WIREGRASS SUBSTATION, 1930-40 Corn yield increases from different nitrogen sources by periods Nitrogen source' Method of application 1930-33 Yield Relative increase increase 1934-37 2 O O rern Yield Bu. Yield Bu. 1938-40 Relative increase 1930-40 average Yield increase Relative increase z 70 4 increase (9.5) increase (7.8)- Bu. Pct. - Pct. Bu. (11.1) Pct. - z None ------------------------------Ammonium nitrate ± limestone --Sidedress 3 Sidedress 3 (15.2) 10.3 18.3 10.2 Sodium nitrate nitrateAmmonium sulfate-----_ Sodium Under Sidedress 3 77 100 77 71 13.6 18.7 18.7 15.7 20.4 20.2 18.2 17.2 17.7 101 100 90 85 88 14.3 17.1 84 15.5 13.9 100 91 81 2 Check yields (in italics) are total yields acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 3Sidedressed plots received 1/ of N at planting and / sidedressing. 9.5 Under 8.0 Ammonium sulfate-----10.9 Sidedress3 U rea - - - ------ - - - - - - - 11.5 Sidedress3 C alcium nitrate----_---. 11.3 Under Diammonium phosphate7.6 Under Cottonseed meal_------4.4 Under Calcium cyanamid -----1 All plots except checks received 36 lb. of N; 24 lb. P20 5 ; and 12 lb. of K2O from muriate of potash. 60 82 86 85 57 18.6 16.9 18.6 14.6 15.1 14.7 14.5 15.3 85 89 19.1 20.9 95 103 92 83 82 18.6 16.7 16.6 14.5 12.8 97 85 75 67 of P 0 33 16.6 11.5 2 5 except the diammonium phosphate plots, which received 98 lb. of per as i0 TABLE 9. CORN YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON LIMED' PLOTS IN A COTTON-CORN ROTATION, NORFOLK FINE LOAM, WIREGRASS SUBSTATION, 1930-40 SANDY Corn yield increases from different nitrogen sources by periods' Nitrogen source 2 Method of application 1930-33 Yield Relative increase increase 1934-37 Yield increase 1938-40 Yield Relative increase increase 1930-40 average Yield Relative increase increase None----------------------Ammonium nitrate ± limestoneSodium nitrate Sidedress -_______ Sidedress -- Bu. (21.8) 4 4 Pct. 93 Bu. (16.0) 12.0 Bu. (11.4) 19.7 18.2 16.6 22.0 18.8 20.1 18.9 19.8 16.1 13.5 Pct. 108 Bu. (16.9) 12.5 12.1 Pct. -IrISuo a 7.5 8.1 5.8 8.8 5.9 8.5 103 Sodium nitrate--------- Under Sidedress 4 sulfate-----. Ammonium sulfate Ammonium ----- 100 72 109 73 11.6 13.2 17.2 16.4 100 91 121 103 110 104 109 88 74 11.4 15.5 13.2 100 94 128 F a a !070 ------Under Sidedress 4 Sidedress 4 Under U rea - - - -- -- - - - -- - -- Calcium nitrate-------Diammonium phosphate------- 9.0 6.5 5.3 5.4 105 111 80 14.6 13.4 15.4 12.7 13.7 13.9 13.3 13.4 109 115 110 -i C 7- Cottonseed meal ------Under Under 65 67 Calcium cyanamid------ 10.9 10.6 111 90 88 m 1 All plots limed with 2,250 lb. calcitic lime in 1930. Sufficient dolomitic limestone mixed with fertilizer each year to neutralize acid-forming sources of nitrogen. 2All plots except checks received 36 lb. of N; 24 lb. P 2 0 5 from superphosphate except the diammonium phosphate plots, which received 93 lb. of P2 0 5 ; and 12 lb. of muriate of potash. 3'Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 4Sidedressed plots received 1/ of N at planting and 3/ as sidedressing. K2O from of z -I z 0 TABLE 10. CORN YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON UNLIMED PLOTS DECATUR CLAY LOAM, TENNESSEE VALLEY SUBSTATION, 1929-45 IN A COTTON-CORN ROTATION, C IIn m 0 Corn yield increases from different nitrogen sources by nsource' Nirgnapplication Method of 1929-33 Yield Relative increase None----------------------Ammonium nitrate + limestone- Sodium nitrate Sodium nitrate Ammonium Ammonium periods 2 1934-37 Yield increase 1938-41 Yield increase Yield 1942-45 Relative increase increase increase 1929-45 average Yield Relative increase increase 'N0 Z :Tm Bu. (27.4) Sidedress3 Sidedress3 Under Sidedress3 Under Sidedress3 Sidedress3 Under Under Pct. -- Bu. (22.2) 17.3 18.8 18.1 17.2 19.6 17.6 20.6 15.7 Bu. (17.4) 27.7 28.7 28.1 25.4 29.0 Bu. (13.2) 16.4 18.4 Pct. Bu. (20.5) 16.0 17.5 17.1 15.8 17.9 16.2 18.2 15.5 14.4 14.6 Pct. - 5.2 6.9 75 100 109 87, 112 88 91 89 100 93 92 91 100 98 90 102 93 104 89 82 83 7.5 6.0 17.2 17.0 17.8 17.1 17.34 15.8 16.3 15.1 sulfate sulfate -------. -------- 7.7 6.1 6.3 5.3 6.5 97 93 94 86 89 U re a-- - - - - - - - - - - - - - - - - - Calcium nitrate----------Diammonium phosphate---Cottonseed 26.7 31.4 77 27.7 22.4 24.4 YV.. meal ---------- Calcium cyanamid -------- 94 14.4 74 5.1 16.1 Under /___________________________-_l VIILL~I IV IVV IV 82 ' All plots except checks received 36 lb. of N; 24 lb. of P20 5 except the diammonium phosphate plots, which received 93 lb. of P2O; and 12 lb. of K20 from muriate of potash. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 3Sidedressed plots received / of N at planting and / as sidedressing. 4Changed to urea in 1942. TABLE 11. CORN YIELD INCREASES FROM VARIOUS SOURCES OF NITROGEN ON LIMED' PLOTS IN A COTTON-CORN ROTATION, DECATUR CLAY LOAM, TENNESSEE VALLEY SUBSTATION, 1929-45 3 Corn yield increases from different nitrogen sources by periods 1929-45 average 1942-45 1934-37 1938-41 1929-33 Relative Relative Yield Yield Yield Yield Yield Relative increase increase increase increase increase increase increase increase Pct. Bu. Pct. Bu. Bu. Bu. Bu. Pct. Nitrogen source Method of application None -- - - - - - - - - Ammonium nitrate + limestoneSodium nitrate Sodium nitrate--------Ammonium sulfate-----Ammonium sulfate -- (32.2) Sidedress 4 4 (26.4) 111 100 160 146 166 114 134 146 126 149 14.0 14.6 13.6 15.0 15.6 18.3 17.7 13.4 13.7 13.9 (20.3) 26.6 (16.0) 19.9 19.2 17.1 16.3 16.4 16.8 16.55 104 100 89 85 (24.2) 15.4 15.5 15.0 - a- Sidedress 3.9 3.5 5.6 5.1 5.8 4.0 99 100, r 27.7 26.1 24.6 Under 97 95 101 101 104 a Sidedress4 Under *Sidedress4 Sidedress 4 Under Under Under 14.7 15.6 ----- 27.1 26.6 Urea - - --- ---- - - - - - - - - Calcium nitrate________ Diammonium phosphate. Cottonseed meal-------Calcium 1All 4.7 5.1 4.4 5.2 28.4 22.6 21.5 12.5 15.8 14.5 cyanamid ----- 24.5 85 87 86 65 82 75 15.7 16.1 12.9 13.3 14.0 C I- 83 86 90 -I plots limed with 2,250 lb. calcitic lime in 1929. Sufficient dolomitic limestone mixed with fertilizer each year to neutralize acid-forming sources of nitrogen. All plots except checks received 36 lb. of N; 24 lb. P2 0 5 from superphosphate except the diammonium phosphate plots, which P 2 05 ; and 12 lb. of K2O from muriate of potash. received 93 lb. 'Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 4Sidedressed plots received / of N at planting and / as sidedressing. 5Changed to urea in 1942. m -v 'I of of z SOURCES of NITROGEN 23 AND EXPERIMENTS WITH AMMONIUM SULFATE SODIUM NITRATE, 1929-45 Experiments with ammonium sulfate and sodium nitrate were begun in 1929 at the Sand Mountain and Tennessee Valley substations, and in 1930 at the Wiregrass Substation and the Monroeville Experiment Field. They were conducted on cotton and corn in a 2-year rotation. Both crops were grown each year on alternate tiers. Treated plots received 36 pounds of nitrogen per acre for each crop. All plots received 48 pounds of P2 0 5 and 24 pounds of K20 per acre for cotton and one-half these amounts for corn. RESULTS ON COTTON Wiregrass Substation, Norfolk Fine Sandy Loam Treatment differences, as shown in Table 12, were small except for the unneutralized ammonium sulfate, which produced a relative yield increase of only 58 per cent in the last period. After 10 years of application, unneutralized ammonium sulfate was producing only 64 per cent as much cotton as sodium nitrate. Basic slag with sodium nitrate increased the pH to 6.6 and slightly decreased the effectiveness of the sodium nitrate. Unneutralized ammonium sulfate decreased the pH from 6.0 to 5.2 in 16 years. Monroeville Experiment Field, Magnolia Fine Sandy Loam Results from all treatments on this soil were similar to those on the Norfolk fine sandy loam, Table 12. The effectiveness of unneutralized ammonium sulfate decreased with time. While the relative yield increase produced by ammonium sulfate in the first period, 1930-33, was 89 per cent of that of sodium nitrate, it decreased to 80 per cent in 1984-37 and to 55 per cent in 1942-45. Sand Mountain Substation, Hartsells Fine Sandy Loam The highest yields at this location were produced by sodium nitrate and by the combination of 1/ ammonium sulfate and 3/4 sodium nitrate, Table 13. Sodium nitrate maintained soil pH about constant over the 16-year period. Basic slag, when used TABLE 12. COTTON YIELD INCREASES FROM AMMONIUM SULFATE AND SODIUM NITRATE WITH LIMESTONE AND BASIC SLAG IN A COTTON-CORN ROTATION, WIREGRASS SUBSTATION AND MONROEVILLE EXPERIMENT FIELD, 1930-45 Seed cotton yield 2 increases from nitrogen sources and amendments by periods Nitrogen source and amendment 1 1934-37 Ntg suena e 1930-33 Yield Relative Yield increase increase increase 1938-41 1942-45 1930-45 average Yield Yield Relative Yield Relative increase increase increase increase increase Jan 19463 Jn Lb. Wiregrass Substation Pat. Lb. (623) Lb. (461) 811 840 544 Lb. (391) 826 900 502 988 871 935 Pct. 95 104 58 113 100 107 85 100 Lb. (528) 675 751 553 769 754 777 Pct. Yr None--------------------------Sodium nitrate ± basic slag---------------------------------Ammonium sulfate basic slag -------------------------Ammonium sulfate----------- (637) 90 100 74 102 100 103 84 94 5.6 6.6 5.9 5.2 6.0 5.9 5.7 5.4 6.2 5.8 + 375 464 463 74 92 92 686 800 702 Ammonium sulfate + limestone4 -------------------------- 454 Sodium nitrate .---------504 Ammonium sulfate + sodium nitrate 1/45-------515 Monroeville Experiment Field (590) None---499 Sodium nitrate + basic slag------------------------------ 532 Ammonium sulfate ± basic slag Ammonium sulfate--------------------------484 4 532 Ammonium sulfate + limestone --------------545 Sodium nitrate -- ---------------------------Ammonium sulfate 1/4 + sodium nitrate 3/46---610 1/4 90 100 102 799 795 807 834 844 852 cc 0 F r (621) 92 98 (369) 482 637 (537) 740 866 (529) 585 659 618 603 rr 89 93 100 574 652 725 492 712 654 474 835 871 55 96 100 506 683 699 72 98 100 5.1 5.6 5.7 112 775 684 849 97 730 104 5.4 plots except checks received fertilizer at rate of 600 lb. 6-8-4 per acre. Check plots received 600 lb. per acre of 0-8-4. Nitrogen applied in split application with 1/ under and 34 as a sidedressing. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 1All z m ''The Limestone m 'Ammonium original pH in 1930 was 6.0 at both locations. sufficient to neutralize acidity of nitrogen material. sulfate applied under and sodium nitrate as a sicledressing. z 0 TABLE 13. COTTON YIELD INCREASES FROM AMMONIUM SULFATE AND SODIUM NITRATE WITH LIMESTONE AND BASIC COTTON-CORN ROTATION, SAND MOUNTAIN AND TENNESSEE VALLEY SUBSTATIONS, 1929-45 SLAG IN A C 70 m N Nitrogen source and amendment Seed cotton yield' increases from nitrogen sources and amendments by periods 1929-33 1934-37 1938-41 1942-45 1929-45 average Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase Jn 1946' z 0 m Lb. Pet. Lb. (500) 697 724 Lb. (552) 911 1,039 Lb. (584) 713 847 264 Pct. 75 89 28 Lb. (557) 719 812 524 Pet. 80 91 59 Sand Mountain Substation None------------------(585) Ammonium sulfate + basic slag __________________________ 84 588 Sodium nitrate ± basic slag .--------------------------672 96 Ammonium sulfate ----------------------------- -- 580 83 4 Ammonium sulfate + limestone -------------------------. 681 97 Sodium nitrate _--------------------------------------702 100 Ammonium sulfate 14 ± sodium nitrate 3/4 714 102 Tennessee Valley Substation z 5.3 5.8 6.6 4.8 531 791 867 851 706 984 1,105 1,085 807 951 944 85 100 99 130 808 894 888 90 100 99 5.6 5.9 5.6 None-------------± basic slag Ammonium sulfate ± basic slag______________ Ammonium sulfate____________4---_-_____Ammonium sulfate + limestone 4 _____________ Sodium nitrate Sodium (1,267) 183 86 (1,146) 271 (1,130) 633 713 753 853 759 (1,112) 408 (1,170) 363 93 5.6 6.3 nitrate ---------------------------sodium nitrate Ammonium sulfate 14+ 95 189 260 212 45 89 123 100 272 377 445 317 378 267 379 314 120 85 121 100 349 384 471 389 89 99 121 100 5.8 5.6 5.7 5.9 3465-__ 252 119 359 829 342 109 434 112 5.7 1 All plots except checks received fertilizer at rate of 600 lb. 6-8-4 per acre. Cbeck plots received 600 lb. per acre of 0-8-4. Nitrogen applied in split application with 1/ under and 34 as a sidedressing. 'Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. pH values of these areas in 1929 were 6.0 at the Sand Mountain Substation and 5.9 at the Tennessee Valley Substation. to neutralize 'Ammonium sufficient applied under acidity of nitrogen material. sulfate and sodium nitrate as a sidedressing. 'Original 'Limestone ~N 26 ALABAMA AGRICULTURAL EXPERIMENT STATION with sodium nitrate, increased soil pH to 6.6 and depressed the yield of cotton. Ammonium sulfate without lime was 83 per cent as effective as sodium nitrate in the first period, 1929-33, but only 61 per cent as effective in the second period, 1984-37. In the last period the relative yield increase was only 28 per cent. The soil pH decreased from 6.0 to 4.8 in 16 years where ammonium sulfate was added without lime. Where limestone was added with ammonium sulfate, yields were similar to those obtained with sodium nitrate. Since some of the calcium requirements of the cotton could be obtained from superphosphate, the low yields with unneutralized ammonium sulfate are probably largely a result of the soil acidity produced. Tennessee Valley Substation, Decatur Clay Loam Yield increases from nitrogen at this location were low for the first few years of the experiment because of the high initial state of fertility of the soil. Differences between sources were not great under these conditions. The 17-year averages in Table 13 show that ammonium sulfate neutralized with limestone was the most productive treatment. Ammonium sulfate when not neutralized decreased soil pH from 5.9 to 5.6. This did not drastically reduce the yield on this heavy soil, even in the 1942-45 period. Basic slag when used with sodium nitrate increased pH to 6.3, but it had little effect on yields as compared to sodium nitrate alone. RESULTS ON CORN Wiregrass Substation, Norfolk Fine Sandy Loam Yield differences between treatments were small. Unneutralized ammonium sulfate produced slightly less than the other sources in the last years of the experiment, Table 14. Monroeville Experiment Field, Magnolia Fine Sandy Loam Data in Table 14 show that all treatments were equally satisfactory on corn except that yields from sodium nitrate plus basic slag plots were lower than the others in the last few years of this experiment. Evidence obtained in later years indicated that this was caused by zinc deficiency resulting from increased pH on these plots. 0 C TABLE 14. CORN YIELD INCREASES FROM AMMONIUM SULFATE AND SODIUM NITRATE WITH LIMESTONE AND BASIC COTTON-CORN ROTATION, WIREGRASS SUBSTATION AND MONROEVILLE EXPERIMENT FIELD, 1930-45 2 SLAG IN A ZI 0 E0 Nitrogen source and amendment' Corn yield increases from nitrogen sources and amendments by periods 1934-37 1938-41 1942-45 1930-45 average Yield Relative Yield Yield Yield Relative Yield Relative increase increase increase increase increase increase increase increase 1930-33 ze 0 G) Bu. Wiregrass Substation N on e - - - - - -- - - - - --- - - - - - - - - - - - - - - - - .------------.Sodium nitrate + basic Pct. 97 90 78 94 100 91 Bu. (8.1) 15.9 16.8 15.4 17.5 16.1 16.6 Ru. 15.3 19.9 17.0 20.1 19.3 19.9 Ru. (6.0) 23.4 23.9 19.6 23.5 25.4 25.3 (10.7) 19.3 Pct. 92 94 Ru. (8.7) 16.7 17.9 15.5 18.2 18.3 18.3 (11.8) 20.4 Pct. 91 98 85 99 100 100 Z Ammonium sulfate + Amm onium sulfate----- ----------------Ammonium sulfate + limestone-----------Sodium slag basic slag ----------- (14.1) 12.1 11.2 9.8 11.7 12.5 11.4 (6.6) 77 93 100 100 nitrate-------------------- -----Ammonium sulfate 1/4 + sodium nitrate 3/4--- Monroeville Experiment Field None -----------------------------------(14.9) Sodium nitrate + basic slag-----------19.3 Ammonium sulfate + basic slag _____________________ 18.2 Ammonium sulfate________________________________17.7 3 Ammonium sulfate + limestone ---17.3 - 106 100 97 95 100 22.3 (12.9) (8.7) 20.6 82 95 Sodium nitrate --------1All ------------------- -------- Ammonium sulfate 1/4 ± sodium nitrate 94 24.3 22.4 23.2 98 plots exept checks received fertilizer at rate of 600 lb. 6-4-2 per acre. Check plots received 600 lb. per acre of 0-4-2. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 3/4----. 18.2 22.3 20.0 21.9 23.4 22.9 23.4 23.1 20.5 24.8 25.4 25.3 23.6 105 108 107 100 22.0 21.6 21.9 21.4 17.1 21. 103 101 102 100 101 'Limestone sufficient to neutralize acidity of nitrogen material. INJ TABLE 15. CORN YIELD INCREASES FROM AMMONIUM SULFATE AND SODIUM NITRATE WITH LIMESTONE AND COTTON-CORN ROTATION, SAND MOUNTAIN AND TENNESSEE VALLEY SUBSTATIONS, 1929-45 BASIC SLAG IN A Corn yield 2 increases from nitrogen sources and amendments by periods Nitrogen source and amendment' 1929-33 Yield Relative increase increase 1934-37 Yield increase 1938-41 Yield increase 1942-45 Relative Yield increase increase 1929-45 average Yield increase Relative increase Bu. Sand Mountain Substation N o n e - --- - - - - - -- - - - - - - - -- - - - - - - -- - - -Sodium nitrate ± basic slagAmmonium sulfate - basic slag Ammonium sulfate-Ammonium sulfate + limestone3 ----------Sodium Pet. 102 87 80 89 100 97 Bu. (5.4) 33.5 29.2 22.9 27.5 30.2 28.5 Bu. (3.6) 35.0 32.7 28.5 30.6 32.6 30.9 Bu. (5.6) 29.3 28.8 22.9 28.1 29.7 28.6 Pct. 99 97 Bu. (6.2) 30.9 28.0 23.7 27.2 29.5 28.2 Pet. (9.5) 26.8 22.8 21.0 23.2 26.2 25.4 77 95 100 96 Ammonium sulfate 14 ± sodium nitrate 34-Tennessee Valley Substation No ne -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Sodium nitrate ± basic slag--------------Ammonium sulfate + basic slag----------Amm onium sulfate------------------ - --Ammonium sulfate + limestone-----------Sodium nitrate-------------------- ------ 95 80 92 100 96 a a (28.5) 5.6 4.9 5.7 6.2 6.5 6.3 86 75 88 95 100 97 (24.3) 18.3 16.9 15.4 18.7 19.4 19.2 (19.6) 31.6 24.0 25.2 25.2 28.7 26.7 (15.0) 20.1 18.6 17.6 19.4 19.0 17.0 106 98 93 102 100 89 (22.2) 18.1 15.4 15.4 16.7 17.7 16.7 102 87 87 94 100 94 C - Ammonium sulfate 1All nitrate-------------------- -----1/4 + sodium nitrate 34-- plots except checks received fertilizer at rate of 600 lb. 6-4-2 per acre. Check plots received 600 lb. per acre of 0-4-2. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks on the basis that soil fertility changes uniformly from one check plot to the next. 3 Limestone sufficient to neutralize acidity of nitrogen material. z SOURCES of NITROGEN Sand Sot \Ioutttain Suibstation, Hlartsells Fine Sauidx Lotant 1 tiisttai, lamge r-esp~onses to 36 pounds of ntitrogen fromt all rees 'ere produted~ at th~is location, Table 15. 'ield increases of as nnieh as :30.9 butsh~els per ac-re wxer e obtainted tront ;36 pottods ofI nitrogten f or- thet entire 1 (cans of the- (\p(rittlett. V'ittetttralr 1( i -' 144 m1 ll ti ( il \(l l I ii( I l ii t iii ii '.1iif itIf [11 (dn v+'e~~~~,~ _.r-<1+. AND AMM\ONILUM\ NITRIATE. 1946-1955 The expernitetts wxitlh attttoutittt sttlfate atid sodlitttl ntitrate prex iottsl* disciissed wxere rex isedi ini 1946 atid atmmonIittmt ntitrate treatttetnts xxere added. Tcsc r('Xisedi ('\peritietts XX tie cont (Ituttedl onl theO satmte plots as prior to 19-16, th erefore the pc itU olts treatmnie ts atndt their r-esidutal ('fleet most 1bet taken it to eoiisideration whet Icot mparing soutrces. T'e prex i( nst treatt et its are gix ei inl all tab les (liset sseti in this section.I 30 ALABAMA AGRICULTURAL EXPERIMENT STATION In the revised experiment, rates of P20 5 and K20 were increased to 60 pounds each for both cotton and corn. Rates of nitrogen were increased to 48 pounds per acre on all plots where sources were compared and former check plots received 36 pounds per acre from neutralized ammonium nitrate. Since the experiments contained no plots that received less than 36 pounds of nitrogen, it is impossible to calculate the total yield increase from nitrogen in the 1946-55 period. The relative yield percentages presented in Tables 16 through 19, therefore, are based on total yield rather than on yield increase from nitrogen as was the case in the previous tables. RESULTS ON COTTON Wiregrass Substation, Norfolk Fine Sandy Loam Unneutralized ammonium sulfate was inferior to all other treatments, Table 16. When used with basic slag or limestone it produced satisfactorily. Ammonium nitrate produced as much as sodium nitrate during 1946-50, but during 1951-55 when unneutralized only 80 per cent as much as sodium nitrate. When used on land that was properly limed, ammonium nitrate produced satisfactorily. Soil pH values in 1955 ranged from 5.1 on the ammonium sulfate plots to 6.5 on the sodium nitrate plus basic slag plots. Monroeville Experiment Field, Magnolia Fine Sandy Loam As shown in Table 16, there were no important differences in yields from the nitrogen sources when ammonium sulfate and ammonium nitrate were neutralized in 1946-55 period. Ammonium sulfate without limestone or basic slag produced only 55 per cent as much as sodium nitrate. Unneutralized ammonium nitrate resulted in a relative yield of 92 per cent. Sand Mountain Substation, Hartsells Fine Sandy Loam Unneutralized ammonium sulfate was much inferior to all other treatments. The 10-year average was only 196 pounds of seed cotton, Table 17. The pH on these plots had decreased to 4.4 by 1955. This was a cumulative effect of ammonium sulfate additions since 1929. A stand of cotton was difficult to maintain on these plots, and when cotton survived it was unthrifty. Crabgrass was always difficult to control on these plots, but it is not 0 e TABLE 16. COTTON YIELDS FROM AMMONIUM NITRATE, AMMONIUM SULFATE, AND SODIUM NITRATE WITH LIMESTONE OR BASIC SLAG IN A 2-YEAR ROTATION OF COTTON AND CORN, WIREGRASS SUBSTATION AND MONROEVILLE EXPERIMENT FIELD, 1946-55 900 scn Seed cotton yields and soil p1, by location and period Nitrogen and amendment treatment' Previous nitrogen and amendment sources' 1980-45 Wiregrass Substation 1946-50 yield 1946-55 Monroeville Experiment Field 1946-55 11 z 0 1951-55 pH in 1946-50 yield Yield Relative 1955 yield yield 1951 yield -55 p in Yield Relative 1955 yield Lb. 1,571 1,507 1,554 829 0 z Lb. Ammonium nitrate ± 3,000 Sodium nitrate ± lb. limestone in 1946m_______________-o-noammonium Lb. 1,286 1,385 1,369 Lb. 1,057 1,143 1,176 610 1,035 1,076 Pet. 98 106 109 57 96 100 Lb. 5.5 6.5 6.3 5.1 Lb. 1,713 1,647 1,670 1,002 Pct. 104 100 103 55 phosphate for P20, Sodium nitrate + basic slag for Ps0S______________________________Same as 1946-55 Ammonium sulfate + basic slag for P20 ______________________________Same as 1946-55 Ammonium sulfate Same as 1946-55 Ammonium sulfate + limestone' -________________ Same as 1946-55 Sodium 828 901 983 1,429 1,367 1,438 656 6.2 6.9 6.0 5.0 ------------------504 716 886 818 1,184 1,334 5.9 5.6 1,342 1,367 1,662 1,659 1,502 1,513 99 100 5.4 5.8 nitrate-------------- Same as + 1946-55 Ammonium sulfate 1/4 Ammonium sodium nitrate 34----------- Same as 1946-55 sulfate 888 1,420 1,154 107 5.8 1,545 1,739 1,642 109 5.8 nitrate ----------Ammonium + limestone every four years 808 1,068 938 87 6.0 1,227 1,553 1,390 92 5.5 'All plots received 48 lb. of nitrogen, 60 lb. P20, from superphosphate or basic slag as noted, and 60 lb. K20 from muriate of potash. 2Plots received fertilizer at rate of 600 lb. 6-4-2 to corn and 600 lb. 6-8-4 to cotton in 1930-45 period. 'Limestone sufficient to neutralize acidity of the nitrogen material. A) w jIoJ TABLE 17. COTTON YIELDS FROM AMMONIUM NITRATE, AMMONIUM SULFATE, AND SODIUM NITRATE WITH LIMESTONE OR BASIC 1946-55 SLAG IN A 2-YEAR ROTATION OF COTTON AND CORN, SAND MOUNTAIN AND TENNESSEE VALLEY SUBSTATIONS, NNN Seed cotton yields and soil pH, by location and period Nitrogen and amendment treatment' Previous nitrogen and amendment 2 source 1929-45 Tennessee Valley Substation Sand Mountain Substation 1946-55 1946-55 pH in pH in 1946-50 1951-55 1946-50 1951-55 ield Relative 1955 yield yield.Y yield yield Yield Relative 1955 yieldyil Sta Ammonium nitrate 3,000 Sodium nitrate + lb. limestone in 1946 --------------monoammonium phosphate Sodium nitrate + basic slag .______________________________________Same as 1946-55 Ammonium sulfate + Same as 1946-55 basic slag Ammonium +- Lb. 1,593 1,539 Lb. 1,447 1,449 Lb. 1,520 1,494 Pct. 98 97 5.4 6.6 5.7 4.4 5.5 5.8 Lb. 1,828 1,739 1,727 1,586 1,816 1,772 Lb. 1,362 1,323 1,397 1,184 1,344 1,220 Lb. 1,595 1,531 1,562 1,385 1,580 1,496 Pct. 107 102 104 93 106 100 6.0 6.7 5.8 5.0 5.5 5.7 5.I a 4.o 5.I a 97 1,465 1,531 1,498 --------------------------------- sulfate Same as 1946-55 136 1,586 1,555 256 1,596 1,535 196 1,591 1,545 13 103 100 C C Ammonium sulfate + Sodium limestone3 ------------------ Same as 1946-55 nitrate-------------- Same as 1946-55 nitrate ---------- Ammonium 4 years Ammonium sulfate 1/4 ±} sodium nitrate /4 __________Same as 1946-55 Ammonium 1,498 1,464 1,440 1,482 1,469 1,473 95 95 5.4 5.1 1,801 1,729 1,267 1,339 1,534 1,534 103 103 5.6 5.3 + limestone every sulfate All plots received 48 lb. of nitrogen, 60 lb. P20 5 from superphosphate or basic slag as noted, and 60 lb. K2 0 from muriate of potash. 2 Plots received fertilizer at rate of 600 lb. 6-4-2 to corn and 600 lb. 6-8-4 to cotton in 1929-45 period. 1 'Limestone sufficient to neutralize acidity of the ammonium sulfate. z SOURCES of NITROGEN 33 known whether this was caused by lack of competition from cotton plants or by an affinity of crabgrass to low pH. Yields of cotton from these plots represent the most severe loss due to acidity that has ever been obtained by the Agricultural Experiment Station. Figure 1-A shows the relative yield increase from ammonium sulfate with and without neutralization with lime and from sodium nitrate from the beginning of the experiment in 1929 to 1955. In the 1951-55 period unneutralized ammonium sulfate produced only 17 per cent as much as did sodium nitrate. With the addition of enough lime for neutralization, however, the ammonium sulfate gave a relative yield of 103 per cent. All other treatments produced about 1,500 pounds of seed cotton per acre. Sodium nitrate and ammonium nitrate were satisfactory sources both with and without lime; however, the plots fertilized with ammonium nitrate had received a neutral fertilizer prior to 1946. When the acidity of ammonium sulfate was neutralized with limestone, the yield was 1,591 pounds, an increase of 1,395 pounds over the unneutralized ammonium sulfate plots. The pH values of the plots in 1955 ranged from 4.4 to 6.6. Continued use of ammonium sulfate after 1946 further decreased the pH from 4.8 to 4.4, while ammonium nitrate decreased the pH from 5.8 to 5.1 in the same period when no lime or basic slag was applied. Although ammonium nitrate without lime had not yet greatly affected the yield, it is expected that yields from this treatment would soon decline because of the low pH produced. Tennessee Valley Substation, Decatur Clay Loam Differences in yield between sources were relatively small, as shown in Table 17. Average yields ranged from 1,385 pounds of seed cotton from unneutralized ammonium sulfate to 1,595 pounds from ammonium nitrate plus lime. Soil pH values in 1955 ranged from 5.0 for unneutralized ammonium sulfate to 6.7 from sodium nitrate plus basic slag. Figure 1-B shows that on this fine textured soil yields from unneutralized ammonium sulfate were as satisfactory as nonacidforming sources, even after 27 years of application. A comparison of 1-A and 1-B clearly illustrates that acid-forming fertilizers may quickly lower yields on coarse textured soils, whereas yields may be satisfactory for much longer periods on fine textured soils. Relative yield of seed cotton in per cent (sodium nitrate 004)HARTSELLS FINE SANDY LOAM r 7 ,r 7 100 ;.h; 120 . sulfate ilmestane"__ ," 1.(J + Ammon.urr,80f}'' , 60. Amanb/urn sulfate Relative yield of seed cotton in per cent (sodium 4 nitrate= 009') r ,; J.2 . r:": +s' ! +yL J ""I ^._*l**! . rrestone 100 < dJ" f !te + 1. mmo-n Su/f , i m m 60 f?' f r b7,r i js; ,::i X .f,,.. s P" t'M v r "f "i t/.PO;s~r2'.+dw .%, + ,S..' : r Amonium; sufate plus d~~9! r f 's f!°1'./ above FigureA1.,Aiing fe comparison. l ii r may lower yoillustrate J J.r 100 ,r , 7't ei rrtr ri t~ r t I t i , w fr r a. y,, y ,q so 80 ' r ) !r h. r + I Is2 1 1 .. r. n ee y ;t tt4 J~ 1 ri4. I ti t 'i y TJ~r J Ik,1 r , WI «9yx :.7i "ti..r S* . .',".7.L-N" r " yfC p }+ / 20 t. r J ! +}V 't nr20 J i 1 ? 4C.;: r," 1 A m07im ^rPZV: 7ti Ij :, ( suf n "7 95 te" . 'rJ n"I i Al S, i 4+Ln.M 199-319437 Am onu I 1384! 1 .... r ,J.. .,. 14-4S , i , i 94-01 1t ? 4:i::": : t.rv 91-5 a 1993 N rJF Va Ly r 1347 $ J ' + r~"rtt:it !7 Y 981 . I ~r7 ~vw''r >/i " 4iY'? , ~ . 4245 1'!' 1946-SO A19-5 l1. y ,' 'h'' '? Ci r . , I. r^ ,"I d1 an f>. . / , y*i1 1,} y vi *--I SOURCES of NITROGEN 35 RESULTS ON CORN Wiregrass Substation, Norfolk Fine Sandy Loam Average yields of corn at this location were low because of several drouthy years, Table 18. Yield differences between treatments were small and not considered to represent important differences between the sources tested. The maximum average yield was 27.4 bushels in the 1946-55 period. Yields that are limited to this level by weather or other uncontrollable factors do not represent reliable measures of differences between treatments. Monroeville Experiment Field, Magnolia Fine Sandy Loam Average yields in the 1946-55 period ranged from 41.7 bushels from ammonium sulfate plus basic slag to 48.2 bushels from ammonium nitrate plus lime, Table 18. Yields from sodium nitrate were intermediate. Within recent years, zinc deficiency symptoms occurred in corn on plots that received sodium nitrate plus basic slag. The pH of these plots in 1955 was 6.9. Zinc sulfate was added to corn plots in this experiment beginning in 1956. No zinc deficiency symptoms were noted during that season. This incident emphasizes the likelihood of zinc deficiency occuring in corn on sandy soil in which the pH gets too high. Sand Mountain Substation, Hartsells Fine Sandy Loam Highest yields of corn were obtained from sodium nitrate in the experiment at Sand Mountain. The three treatments that included this source produced the three highest yield averages, Table 19. Ammonium sulfate was not as effective as sodium nitrate, even when neutralized with dolomite or basic slag. The lowest yield was from unneutralized ammonium sulfate, which produced only 50 per cent as much corn as did sodium nitrate. The acidity produced by ammonium sulfate did not reduce corn yields as drastically as it did cotton yields. The final pH of these plots was 4.4 and corn has been unthrifty on these plots in recent years. Soil pH values of these plots are presented with the cotton yields in Table 17. Tennessee Valley Substation, Decatur Clay Loam All sources of nitrogen were equally satisfactory for corn at the Tennessee Valley Substation, Table 19. The decreases in soil pH caused by the acid-forming nitrogen sources were not great enough to affect corn yields on this heavy red Decatur clay loam. w TABLE 18. CORN YIELDS FROM AMMONIUM NITRATE, AMMONIUM SULFATE, AND SODIUM NITRATE WITH LIMESTONE OR BASIC SLAG IN A 2-YEAR ROTATION OF COTTON AND CORN, WIREGRASS SUBSTATION AND MONROEVILLE EXPERIMENT FIELD, 1946-55 04 Corn yields by location and period Nitrogen and amendment treatment'a Nitogn ndand Previous nitrogen d1946-55 2 source 1930-45 amendment Wiregrass Substation 9 1946-50 yi 1951-55 i Monroeville Experiment Field 11946-55 1951-55 yeld yieRdelative Yield YielddRelative ield yield yield Bu. Sodium nitrate + Ammonium nitrate ± 3,000 - monoammonium phoslb. limestone --------------phate for P205 Sodium nitrate + basic S slag ------ ame as 1946-55 Ammonium sulfate + .ame as basic slagS______________________________1946-55 _------------------ Bu. 30.2 28.8 Bu. 26.9 26.0 Pct. 113 109 Bu. 48.1 43.7 Bu. 48.3 41.7 Bu. 48.2 42.7 Pct. 108 95 jItelr 23.6 23.2 I- 25.0 19.1 22.6 20.9 22.4 29.8 24.5 27.2 26.7 28.2 27.4 21.8 24.9 23.8 25.3 1c 115 92 105 100 106 44.0 43.8 46.2 45.1 47.7 39.4 43.4 43.0 44.5 46.1 41.7 43.6 44.6 44.8 46.9 93 97 100 100 Ammonium sulfate--------Ammonium sulfate Same Same as 1946-55 as 1946-55 as 1946-55 1F 0 limestone' Sodium + ---------------------- nitrate ---------------- Same Ammonium sulfate /4 ± sodium nitrate Ammonium m 105 342---------------- Same as 1946-55 nitrate --------------- Ammonium sulfate limestone every 4 years x z + m 21.1 24.7 22.9 96 48.5 47.5 48.0 107 'All plots received 48 lb. of nitrogen, 60 lb. PRO5 from superphosphate or basic slag as noted, and 60 lb. K2 0 from muriate of potash. 2 Plots received fertilizer at rate of 600 lb. 6-4-2 to corn and 600 lb. 6-8-4 to cotton in 1930-45 period. 'Limestone sufficient to neutralize acidity of the nitrogen material. -I In z C TABLE 19. CORN YIELDS FROM AMMONIUM NITRATE, AMMONIUM SULFATE, AND SODIUM NITRATE WITH LIMESTONE OR BASIC SLAG IN A 2-YEAR ROTATION OF COTTON AND CORN, SAND MOUNTAIN AND TENNESSEE VALLEY SUBSTATIONS, 1946-55 0 X Previous nitrogen amendment treatment 1 Corn yields by location and period Tennessee Valley Substation Sand Mountain Substation 1946-50 1951-55 yield yield Bu. Bu. 1946-55 Yield Bu. Relative yield Pct. 1946-50 yield Bu. 1951-55 yield Bu. 1946-55 Yield Bu. Relative yield Pct. Z 0 and amendment source" 1929-45 G Z Ammonium nitrate + 3,000 lb. limestone in 1946 32.5 47.1 Sodium nitrate + basic as 1946-55 51.4 45.0 slag ___-Same Ammonium sulfate + basic slag ----........-................ Same as 1946-55 42.6 32.2 Ammonium sulfate ....................... Same as 1946-55 29.7 14.9 Ammonium sulfate + limestone. Same as 1946-55 42.2 31.6 Sodium nitrate-............... Same as 1946-55 47.0 43.0 Ammonium sulfate 1/4 sodium nitrate 342 Same as 1946-55 43.6 39.6 Ammonium nitrate-............ Ammonium sulfate + limestone every 31.6 42.6 4 years 1 All plots received 48 lb. of nitrogen, 60 lb. P2O 5 from superphosphate or potash. 2 Plots received fertilizer at rate of 600 lb. 6-4-2 to corn and 600 lb. 6-8-4 Sodium nitrate + monoammonium phosphate for P205 39.8 48.2 37.4 22.3 36.9 45.0 41.6 37.1 88 107 83 50 82 100 92 82 50.3 52.2 48.1 46.7 46.8 49.5 46.7 50.7 37.1 35.2 37.1 36.5 36.8 35.1 36.1 36.9 43.7 43.7 42.6 41.6 41.8 42.3 41.4 43.8 103 103 101 98 99 100 98 104 + basic slag as noted, and 60 lb. K2 0 from muriate of to cotton in 1929-45 period. N 2 Limestone sufficient to neutralize acidity of the nitrogen material. 38 TABLE 20. ALABAMA AGRICULTURAL EXPERIMENT COTTON YIELD INCREASES FROM VARIOUS AND LIMED CHESTERFIELD SANDY STATION ON SOURCES OF NITROGEN MAIN STATION, UNLIMED LOAM, AUBURN, 1928-41 Seed cotton yield increases from different nitrogen sources on unlimed soil by periods Source of nitrogen 1928-31 1932-36 1937-41 1928-41 Yield Relative Yield Yield Relative Yield Relative inc. inc. inc. inc. inc. inc. inc. Lb. Pct. Lb. Lb. Pct. Lb. Pct. None' (490) Sodium nitrate .... 691 Sodium nitrate 3/5, ammonium sulfate 2/5 725 Ammonium sulfate 595 Calcium cyanamid 651 Monoammonium phosphate-..... 458 Urea 672 Calcium nitrate.... 781 Cottonseed meal-- ,.,,,,, 688 ~II I Seed . 100 105 86 94 (431) 923 992 781 853 (283) 1,026 1,166 771 805 _ 100 114 75 78 (395) 894 978 724 778 100 109 81 87 pH 6.0 6.4 6.0 5.5 6.4 5.3 5.8 6.4 5.8 - 66 547 506 49 507 57 97 972 958 93 879 98 113 102 999 97 914 936 852l 1,002 98 844 94 I92 I IIrl I Ir ~ cotton yield increases from different nitrogen sources on limed2 soil by periods 1928-31 1932-36 1937-41 1928-41 Yield Relative Yield Yield Relative Yield Relative inc. inc. inc. inc. inc. inc. inc. pH Lb. None 1_.......... (493) Sodium nitrate---- 640 Sodium nitrate 3/5, ammonium sulfate 2/5_.... 721 Ammonium sulfate 759 Calcium cyanamid 585 Monoammonium phosphate 659 Urea 757 Calcium nitrate 781 Cottonseed meal-.... 604 Pct. 100 113 119 91 103 118 122 94 Lb. (440) 867 1,000 1,010 812 897 861 922 827 Lb. Pct. (325) 1,012 100 1,142 1,134 799 909 1,003 1,115 929 113 112 79 90 99 110 92 Lb. (414) 854 971 983 743 888 882 951 800 Pct. 100 114 115 87 98 103 111 94 7.0 6.5 6.1 6.0 7.0 5.6 6.4 6.6 5.8 Base treatment was 45 lb. of nitrogen from source shown, 600 lb. superphosphate except for the monoammonium phosphate plot, which received 195 lb. of P2Os, and 100 lb. of muriate of potash annually. 1 Figures in italics are actual yields of check plots. All other figures are increases over checks. 2 Limed to pH 6.5 in 1928. Lime to neutralize acidity from nitrogen sources added every 4 years. SOURCES of NITROGEN 39 OTHER EXPERIMENTS WITH SOURCES or NITROGEN ON COTTON SOURCES OF NITROGEN ON UNLIMED AND LIMED CHESTERFIELD SANDY LOAM AT AUBURN, 1928-1941 The experiment consisted of 16 plots, each of which was divided into a limed and unlimed half. Treatments were unreplicated except for the sodium nitrate treatment, which was replicated six times. Yield increases over the no nitrogen treatment are presented by periods, Table 20. On unlimed plots, monoammonium phosphate was the lowest yielding treatment. The relative increase from this source was only 57 per cent of the average increase from the sodium nitrate plots. The pH of this plot in 1942 was 5.3, the lowest produced by any source. Ammonium sulfate produced a relative yield of 81 per cent and had a pH of 5.5 in 1942. Calcium cyanamid was slightly inferior to sodium nitrate, calcium nitrate, and urea. The latter three produced about the same yields. Yields on the limed plots were about the same as on the unlimed, except on the monoammonium phosphate and the ammonium sulfate plots. Lime greatly improved the efficiency of these two sources. An experiment was conducted on Chesterfield sandy loam at Auburn to determine the cause for the low yields obtained with ammonium phosphates. Diammonium phosphate was found to be a satisfactory source of nitrogen and phosphorus when lime and sulfur were applied. With 36 pounds of nitrogen and 48 pounds of P 2 0 5 from urea and diammonium phosphate, the 5-year average seed cotton yield was 501 pounds. The addition of lime increased the yield to 755 pounds and lime plus a source of sulfur (gypsum) increased the yield to 947 pounds. This compares favorably with yields of 929 pounds from superphosphate and sodium nitrate. SODIUM NITRATE AND AMMONIUM SULFATE WITH AND WITHOUT LIME ON, CHESTERFIELD SANDY AUBURN, 1925-55 LOAM, In 1925 an experiment was started on the Main Station Agronomy Farm at Auburn to compare sodium nitrate and ammonium sulfate at two rates of nitrogen with and without lime. All treat- O TABLE 21. SEED COTTON YIELD INCREASES FROM SODIUM NITRATE AND AMMONIUM SULFATE WITH AND WITHOUT LIME, CHESTERFIELD SANDY LOAM, MAIN STATION, AUBURN, 1925-55 2 Seed cotton yield increases from nitrogen by periods 1925-55 average 1951-55 1934-39 1940-45 1946-50 1925-33 Yield Relative Yield Relative Yield Yield Relative Yield Yield increase increase increase increase increase increase increase increase increase Nitrogen treatment' pounds per acre pH in 1956 Lb. Unlimed None ---------------------------------------400 Sodium nitrate -------------------------------300 Ammonium sulfate 3 Pct. -100 38 Lb. (468) 730 518 Lb. (236) 809 612 Lb. (290) 852 762 Lb. (302) 881 562 Pct. 100 64 Lb. (437) 724 489 Pct. 100 68 ------------------408 200 Sodium nitrate ----------------------------------264 150 Ammonium sulfate --------Limed None4---400 Sodium ------------------------- (708) 503 193 5.7 5.8 4.7 ncc 100 65 -- 677 550 552 503 716 594 713 504 100 57 587 458 100 78 5.9 5.1 0 7C 5I 300 Ammonium nitrate ---------------5 5 (725) 730 660 ,100 576414 393 200 Sodium nitrate4---------------452 724 601 422 93 575 150 Ammonium sulfate'------------4 1925-33 All plots received 600 lb. of superphosphate and 100 lb. muriate per acre. 1934-50 All plots received 800 lb. of superphosphate and 200 lb. muriate per acre. per acre. sulfate ------------- 433 553 100 128 (364) 654 (194) 564 793 (296) 896 1,041 (329) 894 895 - 100 100 (419)._ 650 779 100 120 6.4 6.6 6.0 786 LL 100 91 530 535 100 101 6.4 5.8 8a 100 All received 21951-55yields plotsitalics) are 300 lb. of superphosphate, 100 lb. muriate, and over lb. of a minor element Check (in total yields per acre. Other yields are increases checks. ''Beginning in1934, theseinplots received rate of 5,300lime annually. Limestone was applied 1914 at the 180 lb. of lb. 1934, these plots received 360 lb. of lime annually. mixture per acre. z 'Beginning in SOURCES of NITROGEN 41 ments were replicated twice. A summary of 31 years' results from this experiment is presented in Table 21. On the unlimed plots, sodium nitrate was superior to ammonium sulfate at both nitrogen rates throughout the 31 years. The relative increases for the entire period from ammonium sulfate were only 78 and 68 per cent as much as from sodium nitrate at the acre rate of 32 and 64 pounds of nitrogen, respectively. The 300-pound rate of ammonium sulfate reduced soil pH to 4.7 in 31 years. The final pH on the 150-pound rate was 5.1, while the sodium nitrate and no nitrogen plots had pH values of 5.7 to 5.9. The original soil pH of this area is not known. When ammonium sulfate was added to limed soils, yields were about the same as from similar rates of nitrogen from sodium nitrate on unlimed soil. On the limed plots, the two sources produced about the same yields at the low nitrogen rate throughout the 31 years. However, at the high nitrogen rate, ammonium sulfate was superior to sodium nitrate in each period through 1950. In 1951 the superphosphate and muriate applications were reduced and a minor element mixture was added to all plots because it was feared that the high pH on the sodium nitrate plus lime plots was causing a minor element deficiency. Yields from 1951 through 1955 averaged the same for these two treatments, indicating that minor elements may have been in deficient supply. The final soil pH on the limed plots ranged from 5.8 on the 150-pound ammonium sulfate treatment to 6.6 on the 400-pound sodium nitrate treatment. Comparison of the limed and unlimed treatments shows the effect of lime on cotton yields. The average response to lime when used with 150 and 300 pounds of ammonium sulfate were 77 and 390 pounds of seed cotton, respectively. Small and probably insignificant yield decreases from lime were produced on the 200- and 400-pound sodium nitrate treatments. RATIOS OF ORGANIC TO INORGANIC NITROGEN IN FERTILIZERS FOR COTTON ON DECATUR CLAY LOAM, ALEXANDRIA EXPERIMENT FIELD, 1929-43 An experiment to determine the relative efficiencies of organic and inorganic nitrogen for cotton was conducted on the Alexandria Experiment Field for 15 years. Cottonseed meal and sodium nitrate were used as sources of nitrogen. Each treatment was TABLE 22. SEED COTTON YIELD INCREASES FROM VARIOUS PERCENTAGES OF ORGANIC AND INORGANIC LOAM SOIL, ALEXANDRIA EXPERIMENT FIELD, 1929-43 NITROGEN, DECATUR CLAY 1 Percentage nitrogen from Relative Yield Relative Yield Relative Yield increase increase increase increase increase increase Lb. Pct. Lb. Pct. Lb. Pct. (466) (430) -(382) -(426) 8 626 72 492 82 399 92 452 91 75 25 627 72 479 80 375 87 435 88 50 50 728 83 561 93 448 103 508 103 35 65 96 80 439 101 493 100 805 92 579 20 103 110 853 98 618 90 456 105 546 10 100 495 100 873 100 601 100 __100 433 All nitrogen was applied at the rate of 36 lb. per acre before planting. All plots received 60 lb. of P2 0 5 and 24 lb. K20 annually. 2 Check yields (in italics) are total yields per acre. All other yields are increases over calculated checks for each plot based on uniform soil variation between four evenly spaced check treatments. Yield increase Lb. Relative increase Pct. Cottonseed meal Sodium nitrate 1929-33 2 Seed cotton yield increases by periods 1934-38 1989-43 1929-43 Ir C IC i- -I m x m z -I -I -I z SOURCES of NITROGEN 43 replicated twice except the no nitrogen treatment, which was replicated eight times. Results showed that yields were related to the percentage of inorganic nitrogen used in the fertilizer, Table 22. Treatments receiving 90 and 100 per cent of their nitrogen from sodium nitrate produced the highest yields. Plots receiving 50 per cent or more of their nitrogen from cottonseed meal were decidedly inferior. Since inorganic nitrogen is normally cheaper than organic nitrogen, fertilizers should be formulated with inorganic nitrogen unless some organic material is needed for conditioning the fertilizer. GENERAL DISCUSSION Efficient production of cotton and corn in Alabama is impossible without a source of nitrogen in addition to that occurring in soil organic matter. Although the value of the nitrogen sources in the experiments reported here varied with soil conditions and management practices, all increased yields over those obtained without added nitrogen. Several sources of nitrogen were satisfactory for cotton and corn. The effectiveness of nitrogen sources on crop growth was influenced by soil properties other than the supply of available nitrogen. Yields became progressively lower when acid-forming sources of nitrogen were applied without neutralization. However, when adequately neutralized with lime, yields were satisfactory unless some other factor was limiting. The cost of sufficient lime for neutralization is small. With cropping, soils tend to become more acid and the use of neutral fertilizers will not prevent a gradual reduction in soil pH. The soil should be tested every few years and lime applied according to recommendation. Such a liming program will supply the requirements for efficient crop production and prevent development of excessive acidity from acid-forming fertilizers with no danger of overliming. The risk of using acid-forming fertilizers without adequate liming is that they gradually reduce yields as the soil becomes more acid. Thus the grower may not be aware of the loss of yield until the yield level has become seriously reduced. Acid-forming fertilizers may cause low yields in a few years on coarse textured soils, such as sands and sandy loams. On the other hand, it may take 44 ALABAMA AGRICULTURAL EXPERIMENT STATION many years before yields are affected on fine textured soils, such as clays and clay loams. However, reduced yields will eventually occur if acid-forming fertilizers are used without the addition of adequate lime. The use of basic slag with sodium nitrate on certain sandy soils produced symptoms on corn indicating zinc deficiency. After inclusion of zinc in the fertilizer, no deficiency symptoms appeared. Since the zinc supply in these soils is low and becomes less available with increasing basicity, the higher pH produced by continuous use of these two basic materials apparently caused the deficiency symptom. Where cotton and corn received 24 and 12 pounds per acre of potash, greater response was obtained from nitrogen fertilizers when phosphorus was supplied as superphosphate than when basic slag was used. When the rate of potash was increased to 60 pounds per acre, the plots receiving basic slag produced as well as those receiving superphosphate. The low yields obtained from low rates of potash on plots receiving basic slag may be attributed to an increase in potash deficiency caused by the added calcium and the increase in pH. Some loss of nitrogen may have occurred by volatilization of ammonia from the ammonium nitrate-limestone mixtures. This mixture was slightly less efficient than some other sources in several of the experiments. Application of this mixture on the surface of moist soil without immediately covering with soil could result in some loss of ammonia. The low yields produced by the ammonium phosphates were the result of developed acidity and/or sulfur deficiency. Where these materials were the source of phosphate, the plots received no sulfur, whereas ample sulfur was applied on the plots receiving superphosphate (about one-half of superphosphate is calcium sulfate). Unless sulfur is added, cotton yields are often reduced on Alabama soils. Plots receiving the ammonium phosphates often had poor stands, but the cause of the reduced stands is not known. Cottonseed meal, the only natural organic source used in the experiments, was satisfactory on cotton but was no better than the inorganic sources. It did not produce as much corn as some of the inorganic sources. Accordingly, these experiments furnish no basis for the purchase of expensive natural organic materials for cotton and corn. SOURCES of NITROGEN 45 A split application of nitrogen was generally superior to all nitrogen applied before planting. This was probably a result of leaching losses of nitrogen applied before planting, particularly on coarse textured soils in years when heavy spring rains were received. The increased yields as a result of the split application averaged about 8 per cent. SUMMARY This bulletin summarizes the results from 1925 through 1955 of field experiments on sources of nitrogen for cotton and corn. Experiments were conducted on the Main Station, substations, and experiment fields of the Agricultural Experiment Station. Summary tables of the relative yield increases from the nitrogen sources reported in the results section are given in Tables 23 through 26. In making comparisons between percentage figures in these tables, valid comparisons can be made only between sources that appear together in experiments. Ammonium nitrate, ammonium nitrate-limestone mixtures, ammonium sulfate, calcium nitrate, sodium nitrate, and urea are satisfactory sources of nitrogen for cotton and corn provided the acidity produced by the acid-forming sources is neutralized. The ammonium phosphates are satisfactory sources of nitrogen provided the acidity produced is neutralized and the sulfur requirements of the crop are met from other materials. Other sources not used in these experiments may be equally satisfactory. Cottonseed meal as a nitrogen source was satisfactory on cotton, but it was unsatisfactory on corn. Calcium cyanamid and the ammonium phosphates often produced low yields of cotton and corn. Low yields from the ammonium phosphates were probably due to (1) the acidifying effect of the material, and/or (2) sulfur deficiency, since no sulfur was applied to these plots. A primary cause of reduced yields was the low pH produced by the acid-forming sources. Reduced yields resulting from increased acidity were obtained much more rapidly on coarse textured than on fine textured soils. For example, the addition of 36 pounds of nitrogen from ammonium sulfate for 17 years reduced the pH of Hartsells fine sandy loam from about 5.7 to about 4.5, while the pH of Decatur clay loam remained practically unchanged. Yields were reduced after about 5 years of 46 ALABAMA AGRICULTURAL EXPERIMENT STATION application on the Hartsells soil but were not noticeably affected after 17 years on the Decatur soil. Continued use of acid-forming sources of nitrogen without the addition of lime will, however, eventually cause reduced yields on nearly all soils in Alabama. Sodium nitrate, at the rates applied in the experiments reported, maintained the soil pH at an approximately constant level without the addition of lime. Placing a portion of the nitrogen from sodium nitrate or ammonium sulfate under at planting and the remainder as a side dressing usually produced higher yields than when all nitrogen was applied under at planting, especially on sandy soils. A combination of 1/4 nitrogen from ammonium sulfate and 3/4 from sodium nitrate produced as high yields as any single material and maintained the original soil pH at an approximately constant value. The application of limestone at rates determined by the method of Pierre (2) was effective in neutralizing the acidity of the acidforming materials. These experiments show no evidence of a superiority of either the ammonia or nitrate forms of nitrogen for cotton and corn provided other factors, such as soil acidity, are not limiting yields. The major consideration in selecting a source of nitrogen after supplying the lime requirement of the soil, is to use the source that can be purchased and applied at the lowest cost per pound of nitrogen. A price conversion table for sources of nitrogen is found on page 51. SOURCES of NITROGEN 47 SURCES of NITROGEN 4 TABLE 23. SUMMARY OF RELATIVE EFFICIENCY OF VARIOUS SOURCES OF NITROGEN FOR PRODUCING COTTON ON UNLIMED SOILS, 14 LONG-TERM EXPERIMENTS Relative Source of N Hartsls DeauDeauplcmn' Norfolk ecatur Norfolk Hart-sDecatur l Pct. fsclfl Pct. efficiency by soil type Mag-a fs Pct Ammonium sulfate-sodium f Pct. Pct. sl Pct. fsl Pet. nitrate, sidedress--Sodium nitrate, sidedressCalcium nitrate, sidedressUrea, sidedress - Cottonseed meal, under Sodium nitrate, underAmmonium nitratelimestone, sidedress----- 100 92 93 97 101 85 100 93 91 88 91 97 87 78 100 103 99 99 85 89 93 79 99 100 112 100 103 100 104 100 Calcium cyanamid, under--_77 Ammonium sulfate, under--_68 Ammonium sulfate, 65 sidedress -------------Diammonium phosphate, 89 85 (5) 94 46 59 (13) 99 (13) 74 (12) 72 (12) under ---------------Reference table---------Nitrogen applied annually, lb.----------Length of experiment, ( 46 2) ( 3) yr.-- (36) (17) (36) (36) (36) (36) (36) (36) sells Decatur Norfolk Magfsls c2 fs nolia fl f fsl 2 Pet. Pct. Pct. Pet. Ammonium sulfate-sodium nitrate, sidedress -------------95 103 Sodium nitrate, sidedress___ 100 100 Calcium nitrate, sidedress___102 Urea, sidedress Ches- Ches- Chesterfield terfield terfield sl sl sl Pet. Pet. Pet. 107 100 109 100 109 100 100 100 -------- 98 Cottonseed meal, under-----94 Ammonium nitrate, sidedress 95 9__________2________________ 103 87 9 Calcium cyanamid, under--.87 Ammonium sulfate, sidedress ------------under -------- 13 93 57 (16) (10) 55 (16) (48) 81 57 68 (21) (64) 78 (21) (32) Monoammoniurn phosphate, Reference table ___________________ (17) (17) Nitrogen applied annually, lb. (48) (48) Length of experiment, yr.---(10) (10) 1 All sidedress treatments had part of the 2 Relative total yields. Others are relative (20) (45) ------------------(48) (10) (14) (31) (31) nitrogen applied before planting. increases. 48 ALABAMA AGRICULTURAL EXPERIMENT STATION 48 ALABAMA AGRiCULTURLEPRMN TTO TABLE 24. SUMMARY OF RELATIVE EFFICIENCY OF VARIOUS SOURCES OF NITROGEN FOR PRODUCING COTTON ON LIMED SOILS, 14 LONG-TERM EXPERIMENTS Source of N and placement1 Relative efficiency by soil type Hart- Decatur Norfolk MagDecatli Norfolk sells 2 2 nolia ci fsl s ci fsl fsl' Hartsells fsl' Pct. Pet. Pet. Pct. Pct. Pct. Pet. 106 Ammonium sulfate, sidedress 88 105 Ammonium sulfate-basic slag, sidedress ._________________. Ammonium nitrate, sidedress --------------------Sodium nitrate, sidedress_____ 100 100 Calcium nitrate,sidedress___-. 91 99 Monoammonium phosphate, under ------------Urea, sidedress -------------------93 92 Cottonseed meal, under ----85 99 Sodium nitrate, under 90 92 Ammonium nitratelimestone, sidedress---------- 84 96 Calcium cyanamid, under___. 91 93 Ammonium sulfate, under__ 92 83 Diammonium phosphate, under-------------------------------87 74 Reference table-------------------( 6) ( 4) Nitrogen applied annually, lb.--------------------. (36) (36) Length of experiment, yr.---- (17) (11) --------------------------100 130 114 117 89 1002 96 1002 111 1002 113 1002 100 102 1002 --------- (13) (36) (17) (13) (36) (17) (12) (36) (16) (12) (36) (16) (17) (48) (10) Decatur c1 2 Norfolk f sl2 MagnfIa Chester- Chester- Chester- field si field sl field si Pet. Sodium nitrate-sulfate, sidedress---------------114 Pet. Pet. Pet. Pet. Pet. Ammonium sulfate, sidedress______________ 103 slag, sidedress---------102 91 103 100 103 115 89 120 101 Ammonum sulfate-basic Ammonum nitrate, sidedress ------------- 104 Sodium nitrate, sidedress____1002 Calcium nitrate, sidedress__.111 Monoammonium phosphate, Urea, sidedress Cottonseed meal, Reference 92 1002 104 1002 100 98 103 94 100 100 under -------- ----------- under ---(17) (48) (16) (48) (16) (48) Calcium cyanamid, under__ table ---------Nitrogen applied annually, lb.------------ 87 (20) (45) (21) (64) (21) (32) Length of experiment, yr. __ (10) (10) (10) (14) (31) (31) 1All sidedress treatments had part of the nitrogen applied before planting. 2 Basic slag used as the source of phosphorus on these sodium nitrate plots. They did not receive lime. 2 Relative total yield. Others are relative increases. SOURCES of NITROGEN 49 SOURCES of NITROGEN 4 TABLE 25. SUMMARY OF RELATIVE EFFICIENCY OF VARIOUS SOURCES OF NITROGEN FOR PRODUCING CORN ON UNLIMED SOILS, 11 LONG-TERM EXPERIMENTS Relative efficiency by soil type Source of N and placement' Hartfsls DecaturNorfolk Hartsels DecaturNorfolk ci fsi ci fsl Pct. Sodium nitrate, sidedress Ammonium sulfate-sodium nitrate, sidedress Calcium nitrate, sidedress Ammonium nitrate.sidedressSodium nitrate, under --Urea, sidedress---Ammonium sulfate, Ammonium nitrate-limestone, Pct. 100 104 98 93 102 91 90 89 83 82 Pct. 100 97 91 89 Pct. 100 Pct. 100 Pct. 100 100 100 96 91 84 76 89 84 73 67 57 96 94 under 85 84 81 80 87 85 sidedress-- - - -- - - -- - - Ammonium sulfate, sidedress Diammonium phosphate, under Calcium cyanamid, Cottonseed meal, under Reference table----Nitrogen applied annually, lb. Length of experiment, yr. under 85 (36) 7) (10) (36) ( 8) (36) 67 75 (15) (36) (15) (36) (36) (14) Magnolia Hartsells Decatur fsl fsl' cl2 Norfolk Magnolia fsl' fsl' Pet. Sodium nitrate, sidedress__-_--Ammonium nitrate, Pct. 100 92 82 Pet. 100 98 104 Pct. 100 106 96 Pct. 100 105 107 sulfate-sodium 100 101 Calcium nitrate, sidedress__--_. Sodium nitrate, Urea, sidedress sulfate, sidedress----------- Ammonium nitrate, sidedress ___ Ammonium -------------under---_-_ 101 50 98 92 97 under ---- ___-_ Ammonium nitrate-limestone, sidedress-------------- ---Ammonium sulfate, sidedress.-_ Diammonium phosphate, under_ Calcium cyanamid, Cottonseed meal, (14) (19) (19) (18) (18) Reference. table .____________: (36) (48) (48) (48) (48) Nitrogen applied annually, lb.__ (16) (10) Length of experiment, yr._.__-_ (10) (10) (10) 1 All sidedress treatments had part of the nitrogen applied before planting. 2 Relative total yields. Others are relative increases. under---___ under _______ so 50 ALABAMA AGRICULTURAL EXPERIMENT STATION TABLE 26. SUMMARY OF RELATIVE EFFICIENCY OF VARIOUS SOURCES OF NITROGEN FOR PRODUCING CORN ON LIMED SOILS, 10 LONG-TERM EXPERIMENTS Source of N and placement' Relative efficiency by soil type Decatur Norfolk Hartsells Decatur Norfolk cl fsl fsl' ci' fsl' Pct. Pct. Pct. Pct. Pct. 104 110 Calcium nitrate, sidedress Urea, sidedressAmmonium sulfate, Ammonium nitrate-limestone, side dre ss-- - - - - - - - Sodium nitrate, sidedress Ammonium nitrate, sidedress Ammonium sulfate, sidedress Diammonium phosphate, under Ammonium sulfate + basic slag, sidedress under 101 101 99 100 95 83 97 86 115 109 103 100 128 111 94 90 1003 88 100' 92 1003 109 Sodium nitrate, Cottonseed meal, under Calcium cyanamid, under Reference table Nitrogen applied annually, Length of experimn, r Calcium under 91 90 88 (36) (36) 85 107 lb. (6) (36) (36) Legho Magnolia Hartsells Decatur fsl 2 fsl' ci' x ei sidedress et nitrate, Pct. Pct. Pct. Norfolk Magnolia fsl' fsl2 Pct. Pct. r- -_--_ ----Urea, sidedress--------------- Ammonium Ammonium sulfate, under-----100" 108 105 1003 82 76 1003 100 96 97 100' 103 96 105 100' 113 104 98 nitrate-limestone, sidedress -----------------Sodium nitrate, sidedress._-_-_Ammonium nitrate, sidedress_-_- Ammonium sulfate, sidedress___ Diammonium phosphate, underAmmonium sulfate + basic slag, sidedress_______ _______ Sodium nitrate, under_________ Cottonseed meal, under.------Calcium cyanamid, 77 under --- _-_ Reference table._____________. Nitrogen applied annually, Length of experiment, lb.--- (14) (36) 6(1) (19) (48) (10) (19) (48) (10) (18) (48) (10) (18) (48) (10) yr. 1 All sidedress treatments had 2 Basic slag used as the source part of the nitrogen applied before planting. of phosphorus on these sodium nitrate plots. They did not receive lime. 3Relative total yield. Others are relative increases. SOURCES of NITROGEN 51 SOURCES of NITROGEN 5 RELATIVE COST PER POUND OF NITROGEN IN VARIOUS NITROGEN FERTILIZERS Cost per pound of nitrogen Price per ton of material Sodium nitrate 16% N Ammonium sulfate nAm nitrate Nitrogen solution 3 20.5% N 33.5% Urea 45%N %N Nitrogen solution Anhydrous 82.2% N Dollars 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 Cents 9.4 10.9 12.5 14.1 15.6 17.2 18.8 20.3 21.9 23.4 25.0 Cents 7.3 8.5 9.8 11.0 12.2 13.4 14.6 15.9 17.1 18.3 19.5 20.7 22.0 23.2 24.4 25.6 Cents 5.2 6.0 6.7 7.5 8.2 9.0 9.7 10.5 11.2 11.9 12.7 13.4 14.2 14.9 15.7 16.4 17.2 17.9 18.7 19.4 20.2 20.9 Cents 5.4 6.1 6.8 7.4 8.1 8.8 9.5 10.1 10.8 11.5 12.2 12.8 13.5 14.2 14.9 15.5 16.2 16.9 17.6 18.2 18.9 Cents Cents Cents 5.0 5.6 6.1 6.7 5.1 5.6 6.1 6.6 7.2 7.8 8.3 8.9 9.4 10.0 10.6 11.1 11.7 12.2 12.8 13.3 13.9 14.4 15.0 15.6 7.1 7.7 8.2 8.7 9.2 9.7 10.2 10.7 11.2 5.2 5.5 5.8 6.1 6.4 6.7 11.7 12.2 12.8 7.0 7.3 7.6 13.3 13.8 14.3 7.9 8.2 8.5 -- I 52 ALABAMA AGRICULTURAL EXPERIMENT STATION ACKNOWLEDGEMENT In preparing this report, the authors compiled the results of work by many workers of this Station. Experiments at the Main Station from which results are presented were carried out by R. Y. Bailey*, W. V. Chandler*, R. J. Jones*, E. L. Mayton, F. W. Parker*, W. H. Pierre*, D. G. Sturkie, and J. W. Tidmore**. Studies at the substations were conducted by John Boseck, C. A. Brogden, R. C. Christopher*, S. E. Gissendanner, Fred Stewart***, and J. P. Wilson " *. Studies on experiment fields were conducted by H. R. Benford*, C. L. Breedlove*, J. T. Cope, Jr., W. D. Lucas*, J. W. Richardson, J. R. Taylor R. W. Taylor*, and J. T. Williamson " . * Resigned ** Deceased *** Retired SOURCES of NITROGEN 53 LITERATURE CITED (1) NAFTEL, J. A. The Absorption of Ammonium and Nitrate Nitrogen by Various Plants at Different Stages of Growth. Jour. Amer. Soc. Agron. 23: 142-158. 1931. (2) PIERRE, W. H. Nitrogen Fertilizers and Soil Acidity: I Effect of Various Nitrogenous Fertilizers on Soil Reaction. Jour. Amer. Soc. Agron. 20: 254-269. 1928. (3) W. H. Nitrogen Fertilizers and Soil Acidity: II The Use of Fertilizer Combinations, Lime, and Basic Slag in Correcting the Acidity Formed by Various Nitrogenous Fertilizers. Jour. Amer. Soc. Agron. 20: 270-279. 1928. PIERRE, (4) J. W. AND WILLIAMSON, J. T. Experiments with Commercial Nitrogenous Fertilizers. Ala. Agr. Expt. Sta. Bul. 288. 1932. TIDMORE, (5) VOLK, N. J. AND TIDMORE, J. W. Effect of Different Sources of Nitrogen on Soil Reaction, Exchangeable Ions, and Yield of Crops. Soil. Sci. 61: 477-492. 1946.