Anderson, Warren B.

Fenn, Lloyd

Gray, Carl

Kissel, David

Welch, Charles D.

Texas A&amp;M Repository

, - J?- 71L-743CROP FERTILIZATION ON TEXAS BlACKlANDAND GRAND PRAIRIE SOilSCharles D. Welch, Carl Gray, Warren B. Anderson, Lloyd Fenn and David Kissel*The BIackland and Grand Prairie regions, indi-cated in figure I, include 20 million acres of soilswidely varied in characteristics. Moot soils are up-land, but more than 2 million acres of alluvial soilsare included. Three-fourths of the Grand Prairieand about half the Blackland are rangeland.Characteristics of SoilsMost soils are high in clay, and productivitygenerally is regulated by available moisture. Whensoils are dry, initial water intake is high. How-ever, the presence of montmorillionitic-type clayresults in swelling and closure of pores and cracksand a reduced infiltration rate during swelling.-Extension soil chemists, and assistant professor, Texas A&:MUniversity, College Station; and assistant professors, TexasA&:M Research Center, McGregor and Blackland ResearchCenter, Temple, respectively.Figure 1. Locotion of Blackland and Grand Prairie regions.12.5The mineral and rock deposits from whichthese soils are formed are generally high in carbon-ates; therefore, soils have a high base status. Soilshigh in swelling clays require careful attention begiven to a sound residue management program.This is essential for the maintenance of desirablesoil structure and physical characteristics.Soil Fertility StatusSoil characteristics, past fertilization and crop-ping practices have resulted in a wide range offertility levels in these soils. Additions of nitrogenand phosphorus give responses on much of thecropland. For example, soil test summary data inTable I show 70 percent of samples tested to below or very low in phosphorus. However, with themajority of the soils high in potassium, expectedresponses are less frequent than with nitrogen andphosphorus.N, P205 and K20 for Major CropsThe wide range in fertility levels throughoutthe Blackland and Grand Prairie soils requiresthat fertilization practices be adapted to specificconditions. Soil tests, properly calibrated to expressTable 1. Percentage distribution of Blackland and Grand Prairiesoils in five ranges for organic matter, phosphorus, potassiumand pH.Percentage of samplesat each levelSoil test Organic Phos- Potas- Soil pH Per-level * ma.tter phorus sium range centVL 7 50 4 below 6.0 9L 19 20 15 6.1-6.5 16M 22 17 22 6.6-7.3 19H 22 8 21 7.4-7.8 19VH 30 5 38 above 7.8 37*Soil test summary data from Texas Agricultural Extension ServiceSoil Testing Laboratories.Texas A&M University • Agricultural Extension Service • John E. Hutchison, Director • College StationTable 2. Application rates of nutrients for grain sorghum-three production levels.Expected yield Expected yield Expected yieldSoil test3500 Ib./A. 4500 Ib./A. 5500 Ib./ A.level N P2Oi; K20 N P20s K20 N P20 S KliOVL 50 40 40 70 50 50 100 60 60L 30 30 30 50 40 40 80 50 50M 0 20 20 30 30 30 60 40 40H 0 0 20 20 30 30VH 0 0 0 0 0 0Table 3. Appl ication rates of nutrients for cotton-three production levels.Expected yield Expected yield Expected yieldSoil test3/" bale/A. 1 bale/A. 1 1/" bale/A.level N P20 5 K20 N P20 5 K20 N P20 5 K20VL 50 50 50 70 60 80 90 80 100L 30 40 40 50 50 60 70 70 80M 20 30 30 30 40 40 50 60 60H 0 0 30 30 40 40-VH 0 0 0 0 0 0Table 4. Appl ication rates of nutrients for corn-three production levels.Expected yield Expected yield Expected yieldSoil test40 to 50 bu./ A. 50 to 60 bu./ A. 60 to 70 bu./ A.level N P205 K20 N P20n K20 N P20n K20VL 60 40 40 80 50 50 100 60 60L 40 30 30 60 40 40 80 50 50M 20 20 20 40 30 30 60 40 40H 0 0 0 0 30 30VH 0 0 0 0 0 0Table 5. Appl ication rates of nutrients for wheat-three production levels.Expected yield Expected yield Expected yieldSoil test30 bu./ A. 40 bu./ A. 50 bu./ A.level N1 P20 5 K20 N1 P20 S K20 N1 P20 5 K20VL 60 40 40 80 50 50 120 60 60L 40 30 30 60 40 40 90 50 50M 0 20 20 40 30 30 60 40 40H 0 0 0 30 30VH 0 0 0 0 0lApply all of the P20 6 and part of the N at or before planting. Topdress the remainder of the nitrogen in late winter. If small grainsfollow a legume, reduce nitrogen by about half and in proportion to the amount of growth.Table 6. Application rates of nutrients for small grains forgrazing-two grazing intensities.1 a. u./2A. 1 a. u./A.Soil testlevel Nt P205 K20 Nt P20 5 K20VL 60 40 40 140 80 80L 40 30 30 120 60 60M 0 0 0 100 40 40H 0 0 0 0VH 0 0 0 0tApply all of the P205 and K20 and up to 40 pounds of the Nat or before planting. Topdress the remainder of the N inlate winter.available nutrients, and correlated with crop re-sponse, are the best guide to profitable fertiliza-tion. The two important criteria for selecting theprofitable rate of a nutrient are: (1) the level ofavailable nutrients and (2) expected yield goal. Anumber of soil properties, along with the amountof extractable nutrient, must be evaluated to groupsoils for expressing the level of available nutrient.The second criterion is the expected yield, whichexpresses potential productivity and includes antici-pated moisture and management conditions.Rates of N, P20 5 and K20 at varying soil testlevels and expected yields for major crops areshown in Tables 2-9. Soil test levels used in thesetables are based on Texas A&M University proced-ures and calibrations. To use these tables, deter-mine the soil test level in the left column andread across to the expected yield column for therate of nutrient. For example, in Table 2 a soilwith a low (L) level of nitrogen, low (L) level ofphosphorus and very high (VH) level of potassiumwould show 50-40-0 for 4,500 pounds per acre ofgrain soghurn.Calcium, Magnesium and SulfurBlackland and Grand Prairie soils normally arevery high in calcium because of the compositionof the parent material. The magnesium levelsTable 8. Application rates of nutrients for common bermudagrass-(no legume).One application Season totalSoil testlevel Nt P20 5 K20 Nl P20 5 K20VL 70 40 60 140 60 80L 40 30 40 120 40 60M 0 0 0 100 30 40H 0 0 0 0VH 0 0 0 0lFor continuous grazing during favorable seasons. Rates of Nabove 40 pounds should be divided with a portion in the earlyspring (omit with a good legume) and after each grazing period,except the last.appear adequate for current production levels.Sulfur, the third secondary nutrient, has beenstudied less than major nutrients. However, sulfurreleased from organic matter and that supplied bynormal sources of plant nutrients are adequate toprevent widespread deficiencies. Sulfur responseshave not been reported for the Blackland andGrand Prairie regions.MicronutrientsThe micronutrient group includes seven ele-ments: iron, zinc, manganese, copper, boron,molybdenum and chlorine. The amounts of t~e~emicronutrients in Blackland and Grand PraIrIesoils appear to be adequate for current levels ofproduction of field crops. However, there are con-ditions resulting in deficiencies and responses tozinc and/or iron. See Extension leaflets, L-72land L-723, available from county agriculturalagents, for a more complete discussion of thesenutrients.The principle involved in using micronutrientsis the same as for major nutrients; that is, to iden-tify and confirm the need and, the~ to applyamounts sufficient to meet the productIOn requIre-ment.Table 7. Application rates of nutrients for forage (Sudan types) sorghum-three production levels.Expected yield Expected yield Expected yield2 tonI A. 4 ton/A. 6 tonI A.Soil testlevel Nt P20 5 K20 Nt P20 5 K20 Nt P20 5 K2080 40 40 160 80 80 240 100 100VL60 30 30 140 60 60 220 80 80L40 0 0 120 40 40 200 60 60M0 0 0 0 40 40H0 0 0 0 0 0VHlRates of N above 40 pounds should be divided into a preplant application and one or more topdressings after each harvest, exceptthe last.Table 9. Appl ication rates of nutrients for the production of coastol bermudagrass-three production levels (no legumes).Expected yield Expected yieldGrazing only 4 ton/A. 6 toni A.Soil testlevel N1 P20s K20 N1 P20 S K20 N1 P20 S K20VL 160 60 100 180 60 120 280 80 160L 140 40 60 150 40 80 240 60 120M 120 30 40 120 30 60 200 40 100H 0 0 0 30 0 80VH 0 0 0 0 0 0lRates of N above 60-80 pounds should be divided with a portion in the spring (omit with a legu.me) and after each harvest, exceptthe last.Conversion FactorFertilizers are labeled as percent P205 and K20and soil test values are reported in these terms.However, plant analyses results usually are reportedas percentages of the element. For this reason thefollowing factors are presented for us in convertingfrom one form to the other.From P20 5 to P multiply by .44From P to P205 multiply by 2.2From K20 to K multiply by .83From K to K20 multiply by 1.2Importance of Cropping SystemA winter grain crop on clay soils of the Black-land region improves production of the followingsummer crop. This is attributed to better utiliza-tion of moisture and plant nutrients. Seven-yearaverage grain sorghum yields at the Texas A&~IUniversity Research Center at McGregor wereabout the same with no fertilizer following oatsas for 30-30-0 annually with continuous sorghum.Increased moisture following oats allows more timefor nitrogen and phosphorus mineralization, hencehigher yields. In years when moisture was ade-quate during the latter maturity stages, yield dif-ferences were smaller.The effects of oats prior to cotton was evenmore pronounced in that fertilization of contin-uous cotton did not compensate for the effects ofoats. Diseases and other conditions also contributeto these differences. Effective residue and soilmanagement practices are essential for the main-tenance of economical production levels on clayBlackland soils. The soil's physical condition af-fects infiltration, water holding capacity and avail-able water. The structure and physical conditionof clay soils is dependent on the products of cropresidue decomposition. Therefore, to support con-tinuous economical yield levels, farm managersmust combine fertilization, crop rotation, soil andresidue management with other proven productionpractices.Time for Nitrogen ApplicationTo insure high crop yields adequate amountsof nitrogen must be available throughout thegrowing season. This nutrient is absorbed andconverted to protein and other compounds withina short time. This means that a constant nitrogensupply in the ammonium or nitrate form must bepresent to meet daily crop requirements. The peakrequirement, as well as the total needed for theseason, must be satisfied if top yields are produced.For these reasons the greatest efficiency from nitro-gen fertilization is obtained when applied just be-fore it is needed by the crop, however, this is notalways the most convenient or economical.When considering the best time to apply nitro-gen, evaluate the following points:• Ammonium (ammonia) ni trogen is held byclay particles against leaching.• Ammonium is oxidized to nitrate slowly be-low 50 degrees F and rapidly in the 70 to 90degree range.• Nitrate nitrogen moves with water and canbe lost through leaching, especially in coarse-textured soils.• Some nitrogen can be lost from soil throughbacterial denitrification, whereby nitrogenevolves as a gas under anaerobic or water-logged conditions. Denitrification increasesas temperatures rise, especially above 50 de-grees F.• Where nitrogen is applied 2 to 4 months be-fore the period needed by row crops, andconditions have been favorable for losses,additional nitrogen will be needed beforeplanting or as a sidedressing.• Losses of topdressed nitrogen can be sub-stantial if low temperatures and / or high soilmoisture prevents active plant growth forprolonged periods after application.In developing profitable fertilization practices,it is necessary to consider the time of application.Cooperative Extension Work in Agriculture and Home Economics, Texas A&M University and the United States Departmentof Agriculture cooperating. Distributed in futherance of the Acts of Congress of May 8, 1914, as amended, and June 30, 1914.5M-3-71, Revised AGR 11-1

Crop Fertilization on Texas Blackland and Grand Prairie Soils.

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Crop Fertilization on Texas Blackland and Grand Prairie Soils.

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Crop Fertilization on Texas Blackland and Grand Prairie Soils.

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