"To use your soil test re,port to the best advantage, you need to understand the information it provides. With the proper soil test interpretations and suggested fertilizer treatments, you will have a fertilizer program for maximum profitable crop production."--First page.Daryl D. Buchholz, James R. Brown, and Roger G. Hanson (Department of Agronomy, College of Agriculture)Revised 7/89/7

Brown, James R.

Buchholz, Daryl D.

Hanson, Roger G.

English

University of Missouri: MOspace

Archive version - check for updates--Using your~=-=-;;=-;;=;;=;;=-=:=~.-=-====--=;;~===-_=-=---=--=--=== ====Soil test results==========:=:::===:·=-=-·-===· =--===-====--==~ Daryl D. Buchholz, James R. Brown , and Roger G. Hanson Department of Agronomy, College of Agriculture To use your soil test re,port to the best advantage, you need to understand the information it provides . With the proper soil test interpretations and suggested fertilizer treatments, you will have a fertilizer program for maximum profitable crop production. The soil test report provides information on: • Soil test results and ratings • Suggested fertilizer and limestone treatments and (See the sample form on page 2.) • Fertility management practices or concerns. Soil test results and ratings pH5 • The salt pH (pH5 ) of a soil indicates the level of active soil acidity. Crops require different pH5 levels for the best growth and optimum production in terms of yield and economic costs. For example, many row crops, small grains, and legume-grass mixtures should be maintained in soils with a pH5 between 6.1 and 6.5. Alfalfa requires a slightly higher pH5 of 6.6 to 7.0. Many pure grass stands do well in soils with a pH5 of 5.5 to 6.0. Crop production may be severely reduced in soils with a pHs at or below 5.0. As soil pH5 falls below 5.0, aluminum and manganese may increase to toxic levels. Also, phosphorus and molybdenum availabili-ty decreases as soil becomes more acid. Maintained at a pH5 between 5.5 and 7.0, Missouri soils provide a favorable environment for root devel-opment and microorganisms (the living part of the soil). They also provide field crops with the best nutri-ent availability for growth. Limestone recommendations are made to correct the problems of soil acidity. These recommendations are based upon the soil tests, crops to be grown, and the region of the state the sample comes from . See Guide 9102, "Liming Missouri Soils," for more in-formation. Phosphorus (P). In Missouri, the soil test for phospho-rus is called the Bray and Kurtz I or Weak Bray test. The test results are expressed in pounds of elemental P per acre. This test is a measure of the relative availability of phosphorus for plant growth. The test does not measure the total am01,mt of phosphorus in the soil. A very low or low test indicates that crops would very likely respond to the addition of phosphorus fertilizer. Under low soil test conditions, banding a portion of the recommended phosphate may be ad-vantageous. A soil testing medium in phosphorus means that crops are likely to respond to phosphate, if growing conditions are favorable for high yields. Soils testing high in phosphorus are not likely to produce economic yield increases with an application of additional phosphorus. In fact, it would cost more to fertilize than you would get back in profits from increased yield. When soils test in the high range, applying only a small quantity of phosphorus is suggested to maintain the high fertility status. There is no economic advantage to applying phos-phate to soils testing very high. The University of Missouri does not suggest applying phosphorus on soils testing very high in phosphorus. An adequate phosphorus soil test range for row crops and small grains is about 45 to 70 pounds P per acre. Most forage crops do well in a soil testing in a range somewhat lower. An adequate range is 40 to 60 pounds P per acre. Rice, birdsfoot trefoil-grass mix-tures, lespedeza-grass mixtures, and bermuda grass require soil testing in a range of only about 30 to 45 pounds of P per acre for economical production. Native warm season grasses do well on soils testing 20 to 35 pounds of P per acre. CEC. The Cation Exchange Capacity is a measure of the soil's ability to hold certain nutrients known as cations. The CEC on the soil test report is a calculation of the exchangeable calcium, magnesium, potassium, and hydrogen measured by the soil tests. This calcu-MISSOURI COOPERATIVE EXTENSION SERVICE Department ol Agronomy UNIVERSITY OF MISSOURI ~ & LINCOLN UNIVERSITY MP 189 Medium soil K levels indi-cate that crops may respond to potassium if climatic condi-tions are favorable . Extension Programs Soil Test Report Serial no. I Lab no. 214 Waters Hall Columbia. MO 65211 Area County I RP.aion Submitted I Processed FIELD INFORMATION Field 10 I Sample no. Acres I Last Limed I 1rriaated Last crop Soil sample submitted by: Soils with high K levels are not likely to respond to applica-tion, but they should be main-tained at this level. Very high to excess soil K tests show that you can allow crops to deplete potassium until the soil test drops into the high range . This report is for : SOIL TEST INFORMATION RATING Verv low I Low I Medium I Hiah Verv Hiah I Ew:cess pH. Phosphorus (P) lbSla Potassium (K) lbS/a Calcium (Ca) lbSla Maanesium (Ma) lbS/a Sulfur (S0,-Si ppm Zinc (Zn) ppm Manaanese (Mn) ppm Iron (Fe) ppm Copper (C" ) ppm Oraanic matter: % I Neutralizable acidity meq/100a I Cation Exchanae Capacity meq/100o The optimum potassium level for row crops, small grains, and alfalfa hay is (220 + 5 times the CEC) pounds of K per acre. Table 1 gives the adequate soil K ranges for different soil tex-tures and crops. Within these ranges, it's recommended to apply a small quantity of po-tassium to maintain the high fertility status. Sodium (Nal lbS/a I Electrical Conductivitv mmhotcm I SUGGESTED ANNUAL TREATMENTS Yield Pounds per acre Cropping options aoal N P20 s K,O lation is given in milli-equivalents (me.) per 100 grams of soil. The CEC value helps technicians make the po-tassium an~ magnesium interpretations and estimate the soil texture . Potassium (K). This is a measure of the exchangeable potassium in soil extracted with an ammonium acetate solution. The results are expressed as pounds of exchangeable K per acre . The soil test estimates the potassium available to the growing crop. The exchangeable potassium test and CEC are used to interpret the need for additional potassium. In most Missouri soils, the desired level of potassium increases as the CEC ipcreases. The ratings of the potassium soil test levels are similar to those made for phosphorus. Very low to low soil K levels strongly indicate that crops will respond to the application of potassium. Band application of a Zn LIMESTONE s SUGGESTIONS Effective neutralizing material (ENM) Effective magnesium (EMg) portion of the total requirement may also be advan-tageous. Calcium (Ca). An ammonium acetate solution extracts exchangeable calcium from the soil. Calcium seldom limits crop growth in Missouri soils. Even very highly acid soils needing lime usually contain enough calci-um as a plant nutrient for crops. The soil calcium measure~ent is used to calculate CEC. The calcium rating is not based on the actual soil test calcium level. A very low to low soil pH5 (acid soil) is rated medium in calcium. Medium or high soil pH5 (near neutral soil) is rated high in calcium. Magnesium (Mg). An ammonium acetate solution ex-tracts exchangeable magnesium from the soil. Application of magnesium based on soils testing very low to low may improve yields in some forages and row crops. Application on soils testing medium is not Table 1 . Adequate soil potassium ranges based on soil texture and crops grown. Crops Alfalfa hay, row crops small grains Alfalfa-grass pasture and all other forages Sand 240-360 180-270 Soil texture Sandy Silt Clay loam loam loam Clay Adequate potassium soil test ranges (lbs. KIA) 260-390 290-435 320-480 350-525 200-300 230-345 260-390 290-435 9111 Table 2. Nitrogen rate adjustments. 1 Soil texture Cation exchange capacity Sands-sandy loam Silt loams - loam Clay loams - clays (me/lO0g.) less than 10 10-18 greater than 18 1Based on soil texture, organic matter, and time of major growth likely to increase yields in row crops and small grains. However, application may increase magnesium levels in forages and improve forage quality. When mag-nesium is needed and lime is required, the use of dolomitic limestone is recommended. For more information on magnesium require-ments, see Guide 9102, "Liming Missouri Soils ." Organic matter (O.M.). The organic matter soil test is used to estimate potential nitrogen release to a crop throughout the growing season. The test also provides a basis for determining proper herbicide rates. There is no rating system for organic matter be-cause it is relatively stable under normal cropping and fertility practices and cannot be easily changed. Neutralizable acidity (N.A.). Technicians add a buffer solution to the sample used for pH5 analysis to estimate the neutralizable acidity of the soil. Neutralizable acidity is a measure of the exchangeable hydrogen within soil. It is used to calculate the pounds of effec-tive neutralizing material necessary to lime the soil to the proper pH5 range. See UMC Guide 9102, "Liming Missouri Soils." Determining suggested fertilizer rates Nitrogen (N). To calculate nitrogen needs, the yield goal should be realistic, based on crop yield history of the field, irrigation, and your own managerial skills. To calculate nitrogen needs for a crop, • Multiply the nitrogen in the harvested portion of the crop (grain for example) by the yield goal you choose. • Add to that the nitrogen needed to grow the vegetative portion of the crop. • From this amount, subtract the nitrogen your soil will supply (based on the organic matter soil test) . 9111 Cool season Warm season Organic matter crops crops (%) (lbs. N/acre) 0.5 10 20 1.0 20 40 1.5 30 60 2.0 3.0 4.0 2.0 3.0 4.0 5.0 20 30 40 10 15 20 25 40 60 80 20 30 40 50 An example calculation for nitrogen requirement on com. Plant population (1000 ft./acre) Expected yield (bu./acre) 20 150 X4 = 80 X0.9 = 135 Total nitrogen required = ~ Soil nitrogen release Texture (from Table 2) Organic matter C;edit from_ previous legume crop Credit from manure application (See Guide 9331.) Silt loam 2.0% = - (40) Soybeans - 40 bu= - (40) _n_on_e_a~p~p_h_· e_d __ = - ( 0) Additional fertilizer Requirement (lbs . N/A) = ~ In this this example, the final corn population was expected to be 20,000 plants per acre. Multiply this value by 4 pounds of nitrogen per 1,000 plants. That's only the amount of nitrogen needed to grow the crop. The expected yield is 150 bushels per acre. This yield times 0. 9 pounds of nitrogen per bushel, plus the nitrogen to grow the crop indicates the total nitrogen required (from fertilizer, previous legumes, or ma-nures). From the total nitrogen required, subtract all credits to determine the nitrogen fertilizer require-ment. The suggested rate of application accounts for the total nitrogen required and the soil nitrogen release. You must account for additional nitrogen reductions, such as any previous legume crops or manure applica-tion. Consider these sources of nitrogen when you determine how much nitrogen to apply for a crop. For example, you may reduce nitrogen rates by about 30 Table 3. Nitrogen added to the soil by a legume crop (optimum). Legume crop Alfalfa 80-100% stand 50-80% Less than 50% Nitrogen added (lbs. N/acre) Sweet clover (green manure) Red clover (pure stand) Soybeans 120-140 40-60 0-20 100-120 40-60 15-60 Adapted from Follett and Hunter, 1977. Proper fertilizer man-agement saves energy. Kansas State University Publication MF-449. pounds per acre for a crop following soybeans. A good guideline is to reduce about 1 pound of nitrogen for each bushel of the previous soybean crop. Table 3 shows reasonable nitrogen adjustments for a crop fol-lowing a legume under the best growing conditions. Manure applications also supply nitrogen. Al-though the pounds of available nitrogen per ton of dry manure may vary greatly, you can usually reduce nitrogen rates by about 10 to 15 pounds per ton of dry manure. For more information, see UMC Guide 9331, "Animal Manure for Crop Production." Phosphorus (P). Suggested phosphorus rates either build up or maintain the level of phosphorus in the soil. Soils depleted of phosphorus require building up phosphorus for optimum production. If the soil al-ready has an optimal level of phosphorus, the soil test report suggests a maintenance application. Soils test-ing higher than optimum do not usually respond to application, so you can allow the phosphorus level to drop to the optimal range. Phosphorus needs are based on the level required to build up the soil to optimum availability for crop growth. Suggested fertilizer rates are also based on the amount of phosphorus removed from the soil by harvested crops. Table 4 shows the rates necessary to Table 4. Phosphorus rates required for build-up treatments in 8 years. Soil test level (lbs. P/acre) 5 10 15 20 25 30 35 40 Optimal soil test level (lbs. P/acre) 30 40 45 (lbs. P20s/A) 45 56 61 32 43 49 22 34 39 14 25 31 7 18 24 12 17 6 11 5 build up phosphorus to an optimal level with one application. 9111 The University of Missouri presently suggests spreading this buildup over about an eight-year period to reflect expected economic returns from fertilizer application rates . Table 5 shows how much phosphorus is removed by some crops. With this information, you can determine the suggested phosphorus rate by knowing the optimal soil test level, your actual soil test level, and expected crop yield. Calculating a phosphorus treatment. Suppose the soil test is 20 pounds of P, and your yield goal is 150 bushels of corn an acre. Building up your soil from 20 to 45 requires 245 pounds of P20 5 fertilizer. This 245-pound buildup spread over eight years means that you would apply about 31 pounds P20 5 annually (see Table 4) . Table 5. Phosphorus and potassium removed by various crops. Crop removal Crop and yield lbs. P20s/acre lbs. K20/acre Soybeans at 40 bushels/ acre 34 58 Corn (grain) at 100 bushels/ acre 45 30 Corn (silage) at 15 tons/ acre 54 135 Wheat at 60 bushels/ acre 36 18 Alfalfa at 4 tons/acre 40 180 Fescue hay at 4 tons/acre 36 136 1 At a given yield level. Growing 150 bushels of corn per acre removes about 67 pounds of P20 5 • So the suggested phospho-rus rate would be: 31 + 67 = 98 lbs. P20 5 per acre. Potassium. Suggested application rates of potassium are based on amounts needed to build up the soil to the desired level. The rate suggested includes the amount removed by the harvested crop. Table 6 gives the rates necessary to build up soil potassium in one application. Fertilizer recommendations are presently based on build-ing up soil potassium in eight annual applications. Calculating a potassium requirement. Suppose the soil test is 250 pounds of K per acre, and the optimal soil test level is 300 pounds of K per acre (based on soil Table 6. Potassium rates required for build-up treatments in 8 years. Soil test Optimal soil test (lbs. K/acre) level 200 240 (lbs. K/acre) 100 39 52 150 18 31 200 13 250 300 texture and CEC). The yield goal is 150 bushels of corn an acre. The potassium rate to build up the soil from 250 t_o 300 is 114 pounds K20 an acre (see Table 6). This 114-pound buildup spread out over eight years means that you would apply 14 pounds K20 an acre annually. Growing 150 bushels of corn per acre removes 45 pounds of K20 per acre (see Table 4). So the suggested rate would be: 14 + 45 = 59 pounds K20 per acre. Zinc (Zn). You should have the zinc soil test per-formed • on land leveled for irrigation or on recently graded terraces, • on extremely sandy soils, • on soils with high to excessive phosphorus levels, and • on soils under irrigated intensive crop production. In Missouri, a zinc application is likely to increase corn and grain sorghum yields. Table 7 shows ratings and suggested application rates for these two crops, based on the DTPA extractable zinc soil test level. Most row crops, small grains and alfalfa are less likely to respond to zinc fertilization compared to corn or sorghum. Therefore, zinc is recommended for those crops only when the soil test is less than 0.5 ppm. Five (5) pounds actual zinc per acre should be adequate for those crops under the low zinc test-level situations. Table 7. Suggested zinc application rates on corn and sorghum. Soil test level (ppm Zn) Less than 0.5 0.5 - 1.0 Greater than 1.0 Rating Low Medium High Zinc application rate (lbs. Zn/acre) 10 5 0 The suggested zinc applications should correct zinc deficiency and maintain available zinc at an adequate level for at least four crop years. Zinc s~lfate or zinc oxide are adequate fertilizer sources for zmc. If 9111 260 280 300 340 (lbs. K2O/acre) 58 64 69 80 36 42 48 58 19 24 30 41 3 9 14 25 11 you plan to use zinc chelate, apply 113 to ½ of the recommended rate annually. Sulfur (S). Crops may respond to sulfur applied on coarse-textured soils low in organic matter which have been producing high yields. As the soil sulfate-sulfur level or cation exchange capacity increases in soils, the potential response to sulfur decreases. Table 8 outlines Table 8. Ratings of extractable soil sulfur test. Soil sulfate-sulfur (ppm SO4-S) Cation exchange capacity (meq/lO0g) 0-6.5 6.5+ 0 - 7.5 7.5+ Low Adequate Adequate Adequate sulfur interpretations, based on soil sulfate-sulfur and cation exchange capacity. When. these tests show a need for fertilizer sulfur, 10 to 20 pounds of sulfur is suggested for row crops, small grains, and alfalfa. In Missouri, most other forages do not require sulfur, even on soils testing low in sulfur. Additional micronutrients. The potential for econom-ic response to applications of iron, manganese, or copper is not likely with Missouri soils. However, many growers have questions about the level of these nutrients in their soils. Soil tests for iron, manganese, and copper are available through the University of Missouri soil testing labs. Presently, field research has not shown a need for application of these micronutri-ents in Missouri or on similar soils in neighboring states. Table 9 outlines current DTPA soil test interpre-tations for these three micronutrients. Table 9. Iron, copper and manganese soil test interpretations. Soil test rating Low Medium High Iron Copper Manganese DTPA extractable soil test level 0 - 2.0 2.0 - 4.5 4.5+ (ppm) 0 - 0.2 0.2+ 0 - 1.0 1.0+ In areas of the United States where deficiencies of these micronutrients have occurred, the following treatments are the most effective: • Iron: Foliar sprays of 0.5 to 3.0 pounds of iron per acre are the most effective. Soil applications are not as consistent in correcting iron deficiencies . Applying farmyard manure best achieves long-term correction. • Copper: Copper is least likely to show up as a deficiency on our mineral soils in Missouri. Foliar applications according to manufacturer suggestions should be adequate. • Manganese: Foliar or band applications of manga-nese at 1 to 2 pounds of manganese per acre should correct deficiencies that may occur. No soil tests for boron or molybdenum are current-ly offered by the University of Missouri. In Missouri, apply boron annually to alfalfa at a rate of about 1 pound of boron per acre to avoid deficiency. Liming soils to a pH5 of 5.5 or greater should avoid any potential deficiency of molybdenum on any crop grown in Missouri. f'L\l University ~Extension ■ Issued in furtherance of Cooperative Extension Work Acts of May 8 and June 30, 1914 in cooperation with the United States Department of Agriculture. Gail L. Imig, Director, Cooperative UNIVERSITY OF MISSOURI UNCOLN UNIVERS/lY Extension Service, University of Missouri and Lincoln University, Columbia, Missouri 65211. ■ An equal opportunity institution. 9111 Revised 7/89/?M 

Using your soil test results

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Using your soil test results

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