Soil Recommendations

Darryl Warncke, Jon Dahl, Lee Jacobs and Carrie LaboskiDepartment of Crop and Soil Sciences

Michigan State University

MICHIGAN STATEU N I V E R S I T Y

EXTENSION

Extension Bulletin E2904, New, May 2004(Replaces E550A, “Fertilizer Recommendations for Field Crops in Michigan)

NutrientRecommendationsfor Field Crops in

Michigan

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Extension Bulletin E2904, New, May 2004(Replaces E550A, “Fertilizer Recommendations for Field Crops in Michigan)

Nutrient Recommendations for FieldCrops in Michigan

Darryl Warncke, Jon Dahl, Lee Jacobs and Carrie LaboskiDepartment of Crop and Soil Sciences

Michigan State University

Table of ContentsPage

Basis for Recommendations ..........................................................................................................................3Development of Nutrient Management Programs ........................................................................................4Soil Sampling ...................................................................................................................................................4

Soil Test Procedures ...............................................................................................................................5

Soil pH Management ..............................................................................................................................5

Nitrogen Recommendations ..........................................................................................................................7Phosphorus and Potassium Recommendations ........................................................................................10

Calcium..................................................................................................................................................13

Magnesium ..........................................................................................................................................13

Sulfur ....................................................................................................................................................15

Micronutrient Recommendations ................................................................................................................15Boron ....................................................................................................................................................15

Manganese ............................................................................................................................................15

Zinc ........................................................................................................................................................16

Copper ..................................................................................................................................................16

Managing Nutrient Inputs ............................................................................................................................16Environmental Considerations ....................................................................................................................18

Phosphorus Management ....................................................................................................................18

Nitrogen Management ..........................................................................................................................18

Suggested Nutrient Management Practices for Individual Crops ............................................................22Corn Grain and Corn Silage..................................................................................................................22

Soybeans ..............................................................................................................................................23

Dry Edible Beans ..................................................................................................................................24

Small Grains ..........................................................................................................................................25

Sugar Beets ..........................................................................................................................................26

Forage Crops ........................................................................................................................................27

Grass Waterways and Critical Areas ....................................................................................................29

Conservation Reserve ..........................................................................................................................29

Potato ....................................................................................................................................................29

Nutrient recommendations for field crops grown inMichigan have evolved over the years on the basis

of observations and controlled field studies (circularbulletin No. 53, Extension bulletin 159 and Extensionbulletin E-550). During the 1920s and 1930s, recom-mendations given for various amounts of various fertil-izer grades were based on the crop grown and themanagement practices being used. The three manage-ment practice categories were: no manure or legumi-nous green manure in the past two years, clover oralfalfa grown within the past two years, and manuredwithin the past two years. In the 1940s, recommenda-tions for the grade of fertilizer to use considered soiltexture (sandy or loamy or clayey soil) and whethermanure had been applied within two years.

Soil test results began to be considered in making fer-tilizer recommendations in the early 1950s.Phosphorus and potassium test values were classified aslow or high on the basis of the Spurway “reserve” soiltest (0.13 N HCl). For phosphorus, a soil test valuebelow 50 pounds P per acre was considered low andabove 50 pounds P per acre was considered high. Forsoils with a pH above 7.5, the separating value was 100pounds P per acre. For potassium, the separating soiltest value was 150 pounds K per acre. When rockphosphate had been applied to the soil, the “active”test (0.018 N acetic acid) was used. The separatingsoil test values for the “active” test were 25 pounds Pper acre on acid soils, 50 pounds P per acre on soilswith pH above 7.5 and 80 pounds K per acre. Evenwhen the soil test was high, some fertilizer was recom-mended because even in the “high-test” soils it wasusual for an economical response to occur when a bal-anced fertilizer was applied.

In the early 1960s, the Bray P1 test for phosphorusand the ammonium acetate test for potassium began tobe used. Soil test values were divided into very low,low, medium, high and very high categories. In 1963,recommendations for crops grown on mineral soilswere given for amounts of P2O5 and K2O per acre inrelation to the soil test category. For crops grown onorganic soils, the recommendations were given forpounds of P2O5 and K2O per acre on a graded scaleaccording to the actual soil test value. Soon thereafter,nutrient recommendations for all crops grown on min-

eral and organic soils followed the same format. Thetabular recommendations were converted into recom-mendation equations in 1981.

During the mid-1990s, the soil fertility specialists fromMichigan, Ohio and Indiana developed a set of com-mon nutrient recommendations for corn, soybeans,wheat and alfalfa (Extension bulletin E-2567). Theconceptual model used for those recommendations isfollowed for the phosphorus and potassium recommen-dations given in this bulletin for all field crops.

Basis for RecommendationsThe growth and development of field crops can beinfluenced by the levels of essential elements (nutri-ents) available in the soil. Field studies at various loca-tions in Michigan have provided the data for describinggrowth and yield responses of crops to nutrient addi-tions when available soil levels are less than adequate.Soil testing procedures have been developed to relateextractable nutrient levels to crop growth and yield.

Nitrogen, phosphorus and potassium are the nutrientsmost likely to be limiting crop growth. The nitrogenstatus in the soil is quite dynamic, and predicting itsavailability over time is difficult. The availability ofphosphorus and potassium in the soil is fairly stableover time unless major additions are made. Soils inMichigan are naturally quite low in available levels ofphosphorus and potassium. Additions of these twoelements over time in manures and commercial fertiliz-ers have caused significant increases in the available lev-els in the soil. In 1962, the median soil test value(Bray-Kurtz P1) for phosphorus in Michigan soils was12 ppm. This gradually increased over time. Since theearly 1980s, the median value has fluctuated around53 ppm. Similar values for potassium soil test values (1 N neutral ammonium acetate) are 56 ppm and 91ppm, respectively.

Figure 1 illustrates the general relationship betweensoil test value and crop growth or yield. With eachincrement of increase in the soil test value, the increasein yield is less (law of the minimum). The point whereyield reaches 95 to 97 percent of maximum is referredto as the critical soil test value. This is also near thepoint of optimum economic return on investment

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Nutrient Recommendations for Field Crops in Michigan

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made in nutrient additions. When phosphorus orpotassium is added to the soil, some of it is taken upby the growing crop, some goes to increasing the avail-able level in the soil and some is converted into slowlyavailable forms. Adding more of a nutrient than istaken up by the crop will result in a buildup of thereadily available and slowly available forms. Soil testshave been developed that will extract a portion of thenutrient pool that is available to plants as indicated byplant uptake. Soil test values have been correlated withnutrient uptake, growth and subsequently yield. Theamount of a nutrient required to enhance crop growthand yield to the maximum is related to the soil testvalue.

Development of NutrientManagement ProgramsDevelopment of a cost-effective nutrient managementprogram needs to take into account the nutrientrequirements of the crop being grown and the nutrientstatus of the soil. The elemental analyses of plants haveestablished the general nutrient requirements of crops.Actual nutrient uptake will vary with crop yield andvariety. The nutrient requirement of the crop can bemet by nutrients available in the soil and by nutrientadditions. Soil tests indicate the ability of soils to sup-ply nutrients. When the soil is able to supply all of thenutrients required by the crop (the soil test value isgreater than the critical value in Figure 1), no addition-al nutrient inputs are needed to achieve maximumyields. Supplying an amount of nutrient equal to cropremoval will maintain the nutrient status of the soil.Field studies have established how much of a givennutrient to add at a given soil test value to optimizeyield. Soil tests, therefore, provide the base for build-ing a sound nutrient management program.

Soil Sampling Sampling may be the most important part of soil test-ing. Representative samples result in meaningful anduseful soil test information. Soils in all fields havesome degree of variability. It may be due to naturalsoil-forming processes that created differences in soiltexture, organic matter or slope, or it may be due tomanagement practices. Differences in historical crop-ping systems, crop yields, nutrient applications, manureapplications and tillage practices all contribute to vari-ability. Sampling is an averaging process — soil coresshould be taken so that the properties of all cores mak-ing up a composite sample are as similar as possible.Sample unusual or problem soil areas separately.

The first step in collecting soil samples from a field isto map the field and identify areas with similar physicalfeatures and similar historical management practices.Within each designated sampling area, collect about 20cores to a depth of 8 inches and mix them thoroughly.Banding fertilizer contributes to variability of chemicalsoil properties. Where the location of the bands is stillapparent, avoid sampling in the band. Where the loca-tion of the bands is not discernible, collect soil coresfrom more random locations. Collecting one soil sam-ple for at least every 15 to 20 acres will provide goodinformation about the nutrient status of fields. More

Relative soil test value

Rel

ativ

e cr

op

gro

wth

or

yiel

d

Critical Value

(Per

cent

)45

75

90

97

100

Figure 1. Relative growth or yield response toincreasing soil test levels.

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intense sampling will provide more information aboutthe variability in a field. As the number of acres repre-sented by one composite sample increases, the proba-bility that the sample is truly representative of the sam-pled area decreases. In fields that appear uniform, themaximum area that one composite sample should rep-resent is 40 acres, but fewer is better. This approachwill result in samples and test results representative ofthe designated field areas. When only shallow tillage(< 4 inches) or no tillage is used, collect an additionalsample from the surface to 3-inch depth to assess theacidity of the surface soil. Surface soil pH is critical tothe efficacy of some herbicides. (More information onsoil sampling is available in MSU bulletins E-498 andE-1616, and NC Multistate Report 348, (Item SB-7647-S), available from the University of Minnesota)Send 11⁄2 to 2 cups of soil to a reliable soil test lab foranalysis.

Fall and spring tend to be the best and most practicaltimes to collect soil samples. Available nutrient levelsare usually increased prior to or at planting and thengradually decrease during the growing period becauseof plant uptake. By fall the nutrient status is more sta-ble. For long-term nutrient management planning, itis best to take soil samples at the same time of yeareach time a field is sampled. Sampling while the cropis growing is most appropriate for checking availablenitrogen levels; one such test is the presidedress soilnitrate test (PSNT). For most field crop productionsystems, sampling and testing the soil every 3 years isadequate. In more intense cropping systems or wherethe whole aboveground portion of a crop is removed,such as with forages and silage corn, available nutrientlevels may change rapidly. For these situations, sampleand test at least every 2 years. On organic soils, con-siderable amounts of potassium may leach from the soilover winter, especially when the spring thaw occurs.Hence, soil test potassium levels will usually be lowerfor organic soil samples taken in the spring than in thefall.

Soil Test ProceduresThe Michigan State University Soil and Plant NutrientLab uses soil testing procedures recommended by theNorth Central Region Committee on Soil Testing andPlant Analyses (see NCR Pub. 221). Soil pH is deter-mined on a 1:1 soil: water slurry, and the lime require-ment is determined by adding SMP buffer solution to

this slurry and measuring the resulting pH. This valueis reported as the lime index. An index of availablephosphorus (P) is determined according to the Bray-Kurtz P1 (weak acid) test. On soils with free calciumcarbonates, the Bray-Kurtz P1 extraction is less effec-tive. The Olsen (0.5 N sodium bicarbonate) test pro-vides a better indication of P availability on soils withpH above 7.2 and a Bray-Kurtz P1 test of less than 10ppm. An index of available potassium (K), calcium(Ca) and magnesium (Mg) is determined by extractionwith 1 N neutral ammonium acetate.Recommendations for phosphorus, potassium andmagnesium are based on these soil test values.

An index of zinc and manganese availability is deter-mined by extraction with 0.1 N hydrochloric acid.DTPA is used as an alternative extracting solution,especially for calcareous soils. The hot water extractionprocedure is used for boron. Sulfur is determined byextraction with a calcium phosphate solution.

Laboratories with inductively coupled plasma (ICP)spectrophotometers are using the Mehlich III “univer-sal” extracting solution for determining the availabilityindices of P, K, Ca, Mg and other plant-essential ele-ments.

Soil test results are expressed as parts per million (ppm)of P, K, Ca, Mg, Mn and Zn. For mineral soils, 1 ppmis approximately equal to 2 pounds per acre to a depthof 62⁄3 inches.

Conversion FactorsMost soil testing labs report soil test values in terms ofppm P and K. Recommendations are usually given aspounds per acre of P2O5 and K2O because fertilizergrades are expressed as percent N - P2O5 - K2O.Following are the factors for converting from one tothe other.

ppm x 2.0 = lb/A – 62⁄3 inchesppm x 3.6 = lb/A-ftP x 2.3 = P2O5 or P2O5 x 0.43 = PK x 1.2 = K2O or K2O x 0.83 = K

Soil pH ManagementSoil pH provides an indication of the acidity or alkalin-ity of a soil. A pH of 7.0 is neutral, neither acid oralkaline. Values below 7.0 indicate acid soils; values

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above 7.0 indicate alkaline soils. Soil with a pH of 6.0is mildly acidic, a pH of 5.0 is strongly acidic, and apH of 8.0 is mildly alkaline.

Nitrogen, phosphorus, potassium, calcium, magne-sium, boron and molybdenum are most available inmineral soils when the pH is between 6.0 and 7.0.Zinc, manganese, iron and copper tend to be mostavailable when the soil pH is below 6.5. Therefore, itis desirable to maintain the pH of mineral soilsbetween 6.0 and 6.5. As mineral soils become moreacid, especially below 5.5, available aluminum levelsincrease. Increasing aluminum concentration con-tributes to further acidification of the soil and alu-minum toxicity that inhibits root growth. The opti-mum pH varies by crop. Table 1 lists the target pHvalues for most field crops grown in Michigan. Fororganic soils, the target pH ranges from 5.3 to 5.8,depending on the crop. Lower pHs are acceptable inorganic soils because aluminum levels are very low. Alime recommendation is given to raise the soil pH tothe target pH for the crop being grown. If the subsoilof mineral soil is more acid, pH < 6.0, increase the tar-get pH by 0.2 pH unit. When crops with differenttarget pHs are being grown in rotation, lime thesoil for the crop with the highest target pH.

Liming SoilsSoils contain soluble and insoluble sources of acidity.The soil pH indicates the soluble or active hydrogenion concentration in the soil. Changing the pH of acidsoils requires neutralizing the insoluble or boundsources of acidity, usually aluminum and iron com-pounds. The amount of this reserve acidity is deter-mined with the SMP (Shoemaker, McLean, Pratt)buffer and is reported as the “lime index”. Table 2shows how much lime is needed to raise the soil pH upto 6.0, 6.5 or 6.8 when mixed with the top 9 inches ofsoil according to the lime index. Clayey soils tend tobe more resistant to pH change (lower lime index)than sandy soils and require more lime at a given soilpH. Recommended lime rates are based on agricultur-al lime with a neutralizing value (NV) of 90 percent.Adjust lime rate based on the NV of the liming materi-al. Do this by multiplying the recommended amountof lime by 90 and dividing by the NV of the limingmaterial being used — i.e., (lime rate x 90) ÷ NV ofliming material.

Crop Mineral soils Organic soils

Alfalfa seeding 6.8 6.0Alfalfa topdress 6.8 6.0Barley 6.5 5.8Barley/legume seeding 6.5 5.8Beans, dry edible 6.5 5.8Brassica forage 6.5 5.3Bromegrass hay 6.5 5.3Buckwheat 6.5 5.3Canola 6.5 5.3Clover seeding 6.5 6.0Clover topdress 6.5 6.0Clover-grass hay 6.5 6.0Corn grain 6.5 5.3Corn silage 6.5 5.3Corn, seed 6.5 —Grass, warm-season (CRP) 6.0 5.3Grass, cool-season (CRP) 6.0 5.3Millet 6.5 5.3Oats 6.5 5.3Oats for cover 6.5 5.3Orchardgrass hay 6.5 5.3Pasture, intensive grazing 6.5 5.3Pasture, extensive grazing 6.5 5.3Peppermint 6.5 5.5Potato 6.0 5.3Rye grain 6.5 5.3Rye for cover 6.5 5.3Sorghum-Sudangrass hay 6.5 5.3Sorghum-Sudangass haylage 6.5 5.3Soybean 6.5 5.8Spearmint 6.5 5.5Spelts 6.5 5.3Sugar beet 6.5 —Sunflower 6.5 5.3Timothy hay 6.5 5.3Trefoil hay 6.0 5.8Trefoil seed production 6.0 —Wheat grain 6.5 5.8Wheat/legume seeding 6.5 5.8

• Liming the soil above the target pH would not be expectedto improve crop yield unless the subsoil pH is less than 6.0for mineral soils and less than 4.8 for organic soils.

• When crops with different target pHs are being grown inrotation, lime the soil for the crop with the highest target pH.

Table 1. Target soil pH values for field cropsgrown on mineral and organic soils.

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Mineral soils Organic soilsLime Raise soil pH to: Initial Raise pH to:Index 6.0 6.5 6.8 soil pH 5.3

- - tons/A - - - - tons/A - - 70 0.0 0.0 0.0 5.3 0.069 0.0 0.6 0.8 5.2 0.768 1.2 1.6 1.8 5.1 1.467 1.9 2.5 2.9 5.0 2.166 2.7 3.5 3.9 4.9 2.865 3.5 4.4 4.9 4.8 3.564 4.3 5.3 5.9 4.7 4.263 5.1 6.3 6.9 4.6 5.062 5.8 7.2 8.0 4.5 5.661 6.6 8.2 9.0 4.4 6.360 7.4 9.1 10.0 4.3 7.1

Recommendations are based on the following equations:

Mineral soils:To pH 6.0: XL = 54.2 – 0.78 x LITo pH 6.5: XL = 65.5 – 0.94 x LITo pH 6.8: XL = 71.2 – 1.02 x LI

Organic soils:To pH 5.3: XL = 37.6 – 7.1 x pHTarget pH >5.3 XL = (37.6 – 7.1 x pH) +

((target pH – 5.3) x 0.5)where:

XL = Lime recommendation in tons/acreLI = Lime indexpH = Soil pH

Table 2. Tons of limestone needed to raise thepH of mineral soils to 6.0, 6.5 or 6.8 accordingto the lime index, and to raise the pH of organ-ic soils to 5.3 based on the initial soil pH.

The lime rate must also be adjusted if the depth ofincorporation is different from 9 inches. For fieldsbeing farmed with minimal tillage, apply lime at arate to neutralize the acidity in the top 3 or 4 inch-es of soil. For example, if the lime recommendation is3 tons per acre-9 inches, then the lime recommenda-tion for 3 inches equals (3 x [3 ÷ 9]) or 1 ton. Thereactivity of liming materials also varies with the parti-cle size and may influence the rate of material to apply.(MSU Extension bulletin E-471 provides more detailsabout liming materials and liming soils.)

On weakly buffered soils, usually sandy soils, the SMPbuffer may underestimate the lime need. The soil pH

may be sufficiently low to warrant lime application, butthe lime index indicates little or no lime is needed. Ifthe soil pH is 0.3 to 0.5 pH units below the target pHand the lime index indicates that the lime need is lessthan 1 ton per acre, then apply 1 ton lime per acre.Similarly, if the soil pH is 0.6 units or more below thetarget pH and the lime recommendation is less than 2tons per acre, apply 2 tons lime per acre.

Nitrogen RecommendationsApplying the correct amount of nitrogen (N) is impor-tant for profitable crop production, water quality andenergy conservation. Nitrogen recommendations arebased on crop nitrogen utilization and response toapplied nitrogen rates. Table 3 indicates an averageamount of nitrogen removed in the harvested portionof various field crops. Nitrogen recommendations forfield crops grown on mineral and organic soils are list-ed in Table 4. Because of additional mineralization ofN in organic soils, the N recommendations for mostcrops grown on organic soils are 40 to 50 pounds peracre less than those for mineral soils. For the moreresponsive crops, such as corn, the cereal grains, canolaand sugar beets, the amount of nitrogen recommendedvaries according to the yield expected. It is veryimportant that the expected yield used in this calcula-tion be realistic, based on past yields under favorablegrowing conditions. Unrealistically high yield goalswill result in excess nitrogen being applied that mightincrease the risk to groundwater quality, increase lodg-ing of cereal grains, delay maturity or adversely affectcrop quality. Other crops showing less response toapplied N receive a static nitrogen recommendation.

No nitrogen is recommended for the legumes becausethey receive nitrogen fixed from the air by symbioticbacteria. Dry edible beans are the exception. They arenot as effective in fixing nitrogen and benefit fromsome supplemental nitrogen, especially during the earlygrowth stages.

Most legumes leave a positive amount of residual nitro-gen in the soil. When N-responsive crops are grown inrotation with legume crops, credit should be taken forthe amount of residual nitrogen. Table 5 presents theaverage nitrogen credits for various legume and rota-tional crops. Credits may vary, depending on amountof biomass incorporated.


Crop Unit N P2O5 K2O- - - - - - - lb/unit of yield - - - - - -

Alfalfa (Hay) ton 45 13.0 50.0(Haylage) ton 14 3.2 12.0

Barley (Grain) bu 0.88 0.38 0.25(Straw) ton 13 3.2 52

Beans(dry edible) (Grain) cwt 3.6 1.2 1.6Bromegrass (Hay) ton 33 13 51Buckwheat (Grain) bu 1.7 0.25 0.25Canola (Grain) bu 1.9 0.91 0.46Clover (Hay) ton 40 10 40Clover-grass (Hay) ton 41 13 39Corn (Grain) bu 0.90 0.37 0.27

(Stover) ton 22.0 8.2 32.0(Silage) ton 9.4 3.30 8.00

Millet (Grain) bu 1.1 0.25 0.25Oats (Grain) bu 0.62 0.25 0.19

(Straw) ton 13 2.8 57Orchardgrass (Hay) ton 50 17 62Potato (Tubers) cwt 0.33 0.13 0.63Rye (Grain) bu 1.1 0.41 0.31

(Straw) ton 8.6 3.7 21(Silage) ton 3.5 1.5 5.2

Sorghum (Grain) bu 1.1 0.39 0.39Sorghum-

Sudangrass (Hay) ton 40 15 58Sorghum-

Sudangrass (Haylage) ton 12 4.6 18Soybean (Grain) bu 3.8 0.80 1.40Spelts (Grain) bu 1.2 0.38 0.25Sugar beets (Roots) ton 4.0 1.3 3.3Sunflower (Grain) bu 2.5 1.2 1.6Timothy (Hay) ton 45 17 62Trefoil (Hay) ton 48 12 42Wheat (Grain) bu 1.2 0.63 0.37

(Straw) ton 13.0 3.3. 23

Table 3. Nutrient removal in harvest portion of several Michigan field crops.

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Mineral soil Organic soilCrop N recommendation N recommendation

lb N/A lb N/AAlfalfa seeding 0 0Alfalfa topdress 0 0Barley ** **Beans, dry edible 40 0Brassica forage 80 30Bromegrass hay 60 20Buckwheat 60 20Canola ** **Clover seeding 0 0Clover topdress 0 0Clover-grass hay 0 0Corn grain ** **Corn silage ** **Corn, seed **Grass, warm-season

(CRP) 0 0Grass, cool-season

(CRP) 0 0Millet 60 20Oats ** **Oats for cover 40 0Orchardgrass hay 60 30Pasture, intensive

grazing 80 30Pasture, extensive

grazing 60 20Rye grain ** **Rye for cover 40 0Sorghum-

Sudangrass hay 60 30Sorghum-

Sudangrass haylage 60 30Soybean 0 0Sugar beet ** **Trefoil hay 0 0Trefoil seed production 0Wheat grain ** **

** Uses an equation for calculating N recommendation basedon yield goal (YG) and N credit (NC). See Table 5 for nitro-gen credits for previous crops. NC for manure = quantityapplied per acre x N content x 0.5.

Table 4. Nitrogen recommendations forfield crops grown on mineral and organicsoils.

Equations for calculating nitrogen recommendations:

Corn Mineral soil Organic soilCorn grain = (1.36 x YG) – 27 – NC = (1.36 x YG) – 67 – NC

Corn silage = (8.33 x YG) – 25 – NC = (8.33 x YG) – 65 – NC

Corn, seed = (1.63 x YG) – 27 – NC

Barley, Canola, Oats, Rye, WheatMineral soil: N rec. = A + (B x YG)Organic soil: N rec. = Mineral soil N rec. – 30Where:

Barley A = – 12 and B = 0.8Canola A = 50 and B = 0.8Oats A = 0 and B = 0.4Rye A = 0 and B = 0.7Wheat A = – 13 and B = 1.33

Sugar beet: N rec. = 4 x YP

when corn is the previous crop: N rec. = (4 x YP) + 30

Previous crop N credit- - - lb N /A - - -

Alfalfa, established 40 + (% stand)Alfalfa, seeding 40 + 0.5 (% stand)Clover, established 40 + 0.5 (% stand)Clover, seeding 20 + 0.5 (% stand)Trefoil, established 40 + 0.5 (% stand)Barley + legume 30 + 0.5 (% stand)Oats + legume 30 + 0.5 (% stand)Wheat + legume 30 + 0.5 (% stand)Dry edible beans 20Soybeans 30Grass hay 40

Table 5. Nitrogen credit for N-responsivecrops grown in rotation with these crops.


Phosphorus (P) and Potassium (K)RecommendationsResponse of crops to additions of P and K is a continu-ous function. When inadequate amounts are present inthe soil, crops respond to P and K additions withincreases in biomass and/or grain production accord-ing to the general response curve shown in Figure 1.Recommendations given in this bulletin follow thebuildup, maintenance and drawdown philosophypresented in “Tri-State Fertilizer Recommendations,”bulletin E-2567. These recommendations provide forbuildup of available P and K levels when the soil testlevel is below the critical soil test value (Figure 2). Atthe critical soil test level (CL), crop yield will be near95 to 97 percent of maximum. Maintenance recom-mendations (amount equal to crop removal) are givento keep the available P and K at the optimum level andprovide insurance against variations caused by samplingvariability. Beyond the maintenance zone, recommen-dations are less than crop removal to allow drawdownof soil nutrient levels to occur.

Lab so that you receive nutrient recommendations thatare economically and environmentally sound. Table 3provides a guide for average amounts of nitrogen (N),phosphate (P2O5) and potassium (K2O) removed inthe harvested portion of major agronomic crops grownin Michigan. The exact amounts may vary with stageof maturity, environmental conditions, and crop typeor variety.

As indicated, phosphorus recommendations take intoconsideration the soil test level and the crop yield. Thebuildup portion of the recommendation is based onbuilding the soil up to the critical value or level (CL),where yield is 95 to 97 percent of maximum. Buildupassumes that, on average, it takes 20 pounds of P2O5to increase the soil test 1 ppm P or 5 pounds per acreper year over a 4-year period. The P buildup recom-mendations are given in Table 6. The critical levelvaries with the crop and its response to phosphorus(Table 7). The maintenance plateau for most fieldcrops is 15 ppm on mineral soils. Maintaining the soiltest P value in this maintenance zone helps ensure thatP will not limit crop yield. When the soil test P valueis above the maintenance zone, the soil P level shouldbe drawn down so the recommendation is less thancrop removal. The phosphorus critical levels (CL),maintenance plateau length (PL) and drawdown length(DDL) are given in Table 7 for field crops grown onmineral and organic soils. The maximum annual phos-phorus recommendation is 200 pounds P2O5 per acre.

Equations used to calculate the recommendedamount of P2O5, in pounds per acre, when the soiltest is in each zone:

Mineral soils:Buildup: lb P2O5/A = ((CL – ST) x 5) + (YP x CR)

Maintenance: lb P2O5/A = (YP x CR)

Drawdown: lb P2O5/A = (YP x CR) – (((YP x CR) x(ST – (CL + PL))) ÷ DDL)

Organic soils:Buildup: lb P2O5/A = ((CL – ST) x 2) + (YP x CR)

Maintenance: lb P2O5/A = (YP x CR)

Drawdown: lb P2O5/A = (YP x CR) – (((YP x CR) x (ST – (CL + PL)) ÷ DDL

where: CL = critical soil test value (ppm)

ST = soil test value (ppm)

YP = yield potential or goal

Maintenance range

Buildup range

Drawdown range

Nu

trie

nt

reco

mm

end

atio

n r

ate

Soil test level

Critical level Maintenance limit

Figure 2. Nutrient recommendation scheme forphosphorus and potassium.

Crop yield plays an important role in these recommen-dations. In the buildup zone, the amount of P or Krecommended is a combination of the amount requiredto build up the level in the soil to the optimum rangeplus the amount that will be removed in the harvestedportion of the crop. It is very important to providerealistic yield goals to the MSU Soil and Plant Nutrient

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CR = nutrient removal in harvest portion of crop (lb/unit of yield)

PL = maintenance plateau length

DDL = drawdown length; recommendation is phased to zero

Potassium recommendations take into considerationthe soil test level and the crop yield. The buildup por-tion of the recommendation also takes into account thecation exchange capacity (CEC) of the soil. Theamount of potassium required to increase the availablesoil potassium level and reach the critical level (yield is95 to 97 percent of maximum) varies with the CEC.The buildup portion of the K recommendation is givenin Table 8. The maintenance plateau for most fieldcrops is 30 ppm for mineral soils and 25 ppm fororganic soils. In the maintenance zone, the potassiumrecommendation equals crop removal. When the soiltest K value is above the maintenance zone, cropsshould be allowed to use residual soil K and drawdown the soil K level, so the K2O recommendation isless than crop removal. For most crops, in mineralsoils the K2O recommendation goes to zero when thesoil test level is 15 ppm beyond the upper maintenancesoil test value. The critical levels (CL), maintenanceplateau length (PL) and drawdown length (DDL) forfield crops are given in Table 9. The maximum annualpotassium recommendation is 300 pounds K2O peracre.

Equations used to calculate the amount of K2O, inpounds per acre, when the soil test is in each zone.

Mineral soils:Buildup: lb K2O/A = [(CL – ST) x ((1 + (0.05 x CEC))]

+ (YP x CR)

Maintenance: lb K2O/A = (YP x CR)

Drawdown: lb K2O/A = (YP x CR) – [((YP x CR) x (ST – (CL + PL)) ÷ DDL)]

or = (YP x CR) x [1 – {(ST – (CL + PL)} ÷ DDL]

Organic soils:Buildup: lb K2O/A = ((CL – ST) x 1.5) + (YP x CR)

Maintenance: lb K2O/A = (YP x CR)

Drawdown: lb K2O/A = (YP x CR) – (((YP x CR) x (ST – (CL + PL)) ÷ DDL

or = (YP x CR) x [1 – {(ST – (CL + PL)}÷DDL]

where:CL = critical soil test (ppm) for mineral

soils CL = 75 + (2.5 x CEC)CEC = cation exchange capacity (me/100g soil)ST = soil test value (ppm)

YP = yield potential or goalCR = nutrient removal in harvest portion of crop

(lb/unit of yield)PL = maintenance plateau lengthDDL = drawdown length; recommendation is phased to

zero

Organic soils

Soil test values for organic soils are handled and calcu-lated on a volume basis. Organic soils have bulk densi-ties that are much lower than those of mineral soils.On average, organic soils will have field bulk densitiesbetween 0.65 and 0.70, but these may vary consider-ably and may be as low as 0.3 g/cm3. In general, mul-tiplying the soil test value in ppm by 1.5 will approxi-mate pounds per acre to a depth of 6 2⁄3 inches. Hence,the critical soil test values are higher for organic soilsthan for mineral soils.

Buildup recommendations

P soil test CL values

15 20 25 30

ppm - - - - - lb P2O5/A - - - - -

5 50 75 100 125

10 25 50 75 100

15 0 25 50 75

20 0 0 25 50

25 0 0 0 25

30 0 0 0 0

CL = critical soil test value

Table 6. Phosphorus buildup recommenda-tions, mineral soils.

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Mineral soil Organic soilCrop CL1 PL2 DDL3 CL1 PL2 DDL3

- - - - ppm - - - - - - - - ppm - - - -Alfalfa seeding 25 15 10 30 15 10Alfalfa topdress 25 15 10 30 15 10Barley 15 15 10 40 15 10Barley/legume seeding 25 15 10 40 15 10Beans, dry edible 15 25 30 40 15 10Brassica forage 15 15 10 40 15 10Bromegrass hay 15 15 10 40 15 10Buckwheat 15 15 10 40 15 10Canola 25 20 10 55 15 10Clover seeding 20 15 10 30 15 10Clover topdress 20 15 10 30 15 10Clover-grass hay 20 15 10 30 15 10Corn grain 15 15 10 55 15 10Corn silage 15 15 10 55 15 10Corn, seed 20 20 10 — — —Grass, warm-season (CRP) 10 15 10 20 15 10Grass, cool-season (CRP) 10 15 10 20 15 10Millet 15 15 10 40 15 10Oats 15 15 10 30 15 10Oats for cover 25 15 10 30 15 10Orchardgrass hay 15 15 10 30 15 10Pasture, intensive grazing 20 15 10 30 15 10Pasture, extensive grazing 15 15 10 30 15 10Peppermint 40 30 10 70 15 15Potato 60 40 25 120 50 20Rye grain 15 15 10 40 15 10Rye silage 15 15 10 40 15 10Sorghum 15 15 10 40 15 10Sorghum-Sudangrass hay 15 15 10 30 15 10Sorghum-Sudangrass haylage 15 15 10 55 15 10Soybean 15 15 10 35 15 10Spearmint 40 30 10 70 15 15Spelts 15 15 10 40 15 10Sugar beet 15 15 10 — — —Sunflower 15 15 10 40 15 10Timothy hay 15 15 10 — — —Trefoil hay 20 20 10 40 15 10Trefoil seed production 20 20 10 — — —Wheat grain 25 15 10 55 15 10Wheat/legume seeding 25 15 10 55 15 101CL = critical P soil test value2PL = maintenance plateau length3DDL= drawdown length

Table 7. Values for key factors used in calculating the phosphorus recommendations for field crops grown on mineral and organic soils.

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CalciumMichigan soils generally developed from calcareousparent material and therefore contain sufficient avail-able calcium for production of field crops. Soils of thewestern Upper Peninsula, which developed fromacidic parent materials, are the only major exception.Even soils that have become acidic and need lime gen-erally contain sufficient calcium to meet the needs offield crops. Poor plant growth in acid soils is usuallydue to the excess uptake of aluminum and/or man-ganese rather than calcium deficiency. The best wayto be sure that soils contain adequate calcium is to soiltest regularly and apply lime as needed. Supplementalcalcium may improve tuber quality of potatoes grownon sandy soils containing less than 300 ppm exchange-able calcium. Maintaining adequate soil moisture isimportant for adequate calcium uptake.

Studies in Michigan, Indiana, Ohio and Wisconsinhave shown alfalfa and corn to yield equally well over awide range of calcium to magnesium ratios. Addingcalcium to improve the calcium to magnesium ratio isnot necessary unless the amount of magnesium equalsor exceeds calcium on an equivalence basis (milliequiv-alents per 100 grams soil). The calcium to magnesium

ratio may be helpful in determining whether to use cal-citic or dolomitic limestone when lime is needed.

MagnesiumMagnesium (Mg) deficiency is most likely to occur inacid sandy soils with a subsoil as coarse or coarser thanthe surface soil. These soils are most common in thesouthwestern and western areas of Michigan. Usedolomitic limestone (contains calcium and magnesium)on low-magnesium acid soils to neutralize soil acidityrather than using calcitic lime or marl (contain primari-ly calcium), which may induce a magnesium deficiency.Potatoes, corn and oats are the field crops most sensi-tive to marginal magnesium levels.

Application of magnesium is recommended on thebasis of one of the following criteria: when the soiltest value is less than 35 ppm on sandy soils or lessthan 50 ppm on fine-textured soils, when magnesiumis less than 3 percent (as a percent of exchangeablebases on an equivalence basis), or when exchangeablepotassium exceeds the percent magnesium on an equiv-alence basis (milliequivalents per 100 grams of soil).On acid soils where magnesium is needed, apply atleast 1,000 pounds of dolomitic limestone per acre.For non-acidic soils low in magnesium, broadcast 50 to100 pounds of actual magnesium per acre or include10 to 20 pounds of magnesium per acre in band-placed fertilizer. Suitable sources of magnesiuminclude magnesium sulfate, potassium-magnesium sul-fate and granulated finely ground magnesium oxide-magnesium sulfate (granusols). Broadcasting 200 to400 pounds of dolomitic limestone on non-acidic soilsis also an acceptable practice because it will cause onlya modest increase in soil pH. Magnesium deficienciescan be corrected by spraying 1 to 2 pounds Mg peracre on the crop foliage. Using lower rates than thismay require multiple applications.

Magnesium deficiency may be induced by applyinghigh rates of potassium fertilizer. This can result ingrass tetany disorder in livestock that feed on lushgrass. Where forages are being grown, agronomistsfrequently strive for magnesium to be 10 percent ofthe total exchangeable bases (equivalency basis). Ifthere is concern about grass tetany, avoid applying highrates of potassium (more than 200 pounds per acre) in

CEC, me/100 g4 8 12 16

K soil test CL 85 95 105 115Buildup recommendation

ppm - - - - - lb K2O/A - - - - -

10 90 119 152 18920 78 105 136 17130 66 91 120 15340 54 77 104 11750 42 63 88 9960 30 49 72 8170 18 35 56 6380 6 21 40 4590 0 7 24 27

100 0 0 8 0110 0 0 0 0120 0 0 0 0

CL = 75 + (2.5 x CEC)

Table 8. Potassium buildup recommendations,mineral soils.

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Mineral soil Organic soil

CL1= 75+(2.5 x CEC)

Crop PL2 DDL3 CL1 PL2 DDL3

- - - ppm - - - - - - - - ppm - - - - -Alfalfa seeding 0 50 140 25 95Alfalfa topdress 0 50 140 25 95Barley 30 20 190 25 15Barley/legume seeding 30 20 190 25 15Beans, dry edible 30 20 220 25 15Brassica forage 30 20 180 25 15Bromegrass hay 30 20 140 25 15Buckwheat 30 20 180 25 15Canola 30 20 220 25 15Clover seeding 30 20 140 25 95Clover topdress 30 20 140 25 95Clover-grass hay 10 50 140 25 95Corn grain 30 20 220 25 25Corn silage 0 20 220 25 25Corn, seed 0 20 — — —Grass, warm-season (CRP) 30 20 140 25 15Grass, cool-season (CRP) 30 20 140 25 15Millet 30 20 220 25 15Oats 30 20 160 25 15Orchardgrass hay 30 20 140 25 15Pasture, intensive grazing 30 20 140 25 15Pasture, extensive grazing 30 20 140 25 15Peppermint 30 20 220 40 60Potato 30 20 180 60 160Rye grain 30 20 160 25 15Rye silage 30 20 160 25 15Sorghum 30 20 220 25 15Sorghum-Sudangrass hay 30 20 130 25 100Sorghum-Sudangrass haylage 30 20 130 25 100Soybean 30 20 220 25 15Spearmint 30 20 220 40 60Spelts 30 20 220 25 15Sugar beet 30 20 — — —Sunflower 30 20 220 25 15Timothy hay 30 20 — — —Trefoil hay 30 20 140 25 15Trefoil seed production 30 20 — — —Wheat grain 30 20 220 25 15Wheat/legume seeding 30 20 220 25 15

1CL = critical P soil test value2PL = maintenance plateau length3DDL= drawdown length

Table 9. Values for key factors used in calculating the potassium recommendations for field crops grown on mineral and organic soils.

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a single application. Use of supplemental magnesiumin the feed ration may also help avoid grass tetany.Contact your animal feed specialist for guidance.

SulfurPlants take up sulfur in amounts similar to phosphorus.The primary sources of plant-available sulfur are soilorganic matter (animal manures or plant residues) andatmospheric deposition. Significant reductions inatmospheric deposition of S have increased the poten-tial for sulfur deficiency. Crops growing in sandy soilslow in organic matter are the most likely to show sulfurdeficiency. Studies in the past with sulfur-responsivecrops grown on potentially sulfur-deficient sites inMichigan have not been shown to benefit from supple-mental sulfur application. Many soils have an accumu-lation of sulfur in the subsoil that the crops access oncethe roots reach that depth, especially where there is anincrease in clay content. Crops most likely to benefitfrom sulfur application are alfalfa and canola. Newstudies are needed to reevaluate the need for sulfur byother crops grown in Michigan soils.

Micronutrient RecommendationsMicronutrient recommendations are based on soiltest, soil pH and crop responsiveness. The responsive-ness of selected field crops is given in Table 10.Equations used to calculate the recommended amountsto apply are given at the beginning of each section.

BoronBoron recommendations are based on crop response,not on soil tests. A boron soil test (hot water soluble)can provide a general guide to whether the status islow (<0.7 ppm), marginal or adequate (>1.0 ppm).Boron occurs in the soil primarily as a water-solubleanion that is subject to leaching, so the availableboron status may change over time, especially in sandysoils. Boron readily leaches out of sandy soils over thewinter and early spring months, when precipitationexceeds evapotranspiration. Some leaching may alsooccur in fine-textured soils but to a lesser degree. Forresponsive crops such as alfalfa, boron deficiency mayoccur when soil moisture is marginal even though thesoil contains adequate boron. Application of 2 poundsof boron per acre per year is recommended for alfalfagrown on sandy soils (CEC <8.0 me/100 grams soil).On fine-textured soils, boron application is usually not

beneficial except for high-yielding established alfalfafields, where a topdress boron application (0.5 to 1.0pound per acre) is suggested.

Recent research with newer sugar beet varieties hasshown supplemental boron is not necessary when beetsare grown in soils of the Thumb and Saginaw Valleyareas. On loamy sands and sandy loams, 1 to 2 poundsper acre is suggested. Field beans, soybeans and smallgrains are sensitive to boron application. For thesecrops, avoid using boron in the starter fertilizer. Theresidual boron level from a previous year’s applicationshould not be of concern for these sensitive cropsunless higher than recommended rates were applied.

ManganeseFor responsive crops, recommended amounts of man-ganese (Mn) are based on soil test (ST) (0.1 N HCl)value and soil pH according to the following equa-tions:

Mineral soils: Mn rec. = (6.2 x pH – 0.35 x ST) – 36Organic soils: Mn rec. = (8.38 x pH – 0.31 x ST) – 46

where Mn recommendation is lb Mn/A (band application only)ST is soil test value, ppm Mn

Manganese availability decreases markedly as soil pHincreases. In mineral soils, the critical soil test value is6 ppm at pH 6.3 and 12 ppm at pH 6.7. In organicsoils, the critical soil test value is 4 ppm at pH 5.8 and16 ppm at pH 6.2. Liming acid soils may induce amanganese deficiency. Manganese deficiency is mostlikely to occur on organic soils with a pH above 5.8and dark-colored mineral soils in lakebed and glacialoutwash areas with a pH above 6.5. Recommendedrates of manganese are for band application becausemanganese is readily bound into unavailable formswhen mixed (broadcast and incorporated) with thesoil. Flooding and fumigation temporarily increasemanganese availability, but it readily decreases once thesoil dries and microbial populations are reestablished.Manganese sulfate has proven to be the most suitablecarrier for soil application, though granulated finelyground manganous oxide-sulfate mixtures (granusols)and some chelates are also acceptable sources on min-eral soils. Manganese chelates are not recommendedfor application in organic soils. It is difficult to buildup the available manganese status of soils. Therefore,

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if a manganese deficiency occurs in a field one year, itwill likely reoccur each year, especially when sensitivecrops are grown.

Oats, dry edible (field) beans, potatoes, soybeans,sorghum-Sudangrass, sugar beets and wheat are mostresponsive to manganese. Under high pH conditions,barley may also respond to manganese application.Manganese deficiency in these crops can be alleviatedby spraying the crop foliage with 1 to 2 pounds Mnper acre. Under severe conditions and when lowerrates are used, multiple applications may be necessary.If symptoms persist or appear on the new foliage 10days after application, make another application.Some manganese carriers have been shown to reducethe efficacy of glyphosate when the two are tank mixedor sprayed sequentially within 48 hours. ManganeseEDTA (ethylenediaminetetraacetic acid) has shownminimal adverse effect.

Zinc For responsive crops, recommended amounts of zinc(Zn) are based on soil test (ST) (0.1 N HCl) value andsoil pH according to the following equations:

Mineral and organic soils: Zn rec. = (5.0 x pH – 0.4 x ST) – 32where Zn recommendation is lb Zn/A

ST is soil test value, ppm Zn

Michigan soils with a pH less than 6.5 generally con-tain adequate zinc to meet the needs of field crops. AtpH 6.6, the critical soil test value is 2 ppm; at pH 7.0,it is 7 ppm. Zinc deficiency is most likely to occur onthe alkaline mineral soils of the lakebed regions of east-ern Michigan and on near neutral to alkaline organicsoils. Deficiencies are also likely to occur on spoil-bankareas and areas where tiles were trenched into calcare-ous subsoil. High rates of phosphorus may enhancethe occurrence of a zinc deficiency when the availablesoil zinc status is marginal. Dry edible beans, corn andsorghum-Sudangrass are the field crops most sensitiveto low levels of available zinc. Band application of therecommended zinc rate is preferred, but broadcastapplication of 10 pounds or more per acre is effectivein meeting the need of the crop and building up thesoil level. Annual band applications will graduallybuild up available zinc levels and eliminate the need forfurther applications. Zinc sulfate, granulated finelyground zinc oxide-sulfate mixtures and chelates aregood sources of zinc for soil application. Chelates areactually more effective than the inorganic salts in

improving the zinc availability for a given growing sea-son. The recommended rate for zinc chelates is one-fifth the rate calculated above for the inorganic salts.

CopperCopper (Cu) is recommended for organic soils basedon the 1 N HCl soil test.

Cu rec. = 6 – (0.22 x ST)where Cu recommendation is lb/A

ST is soil test value, ppm

The mineral soils of Michigan generally contain ade-quate amounts of copper. Soil test values greater than0.5 ppm (1N HCl extractable) indicate adequate cop-per availability. Acid sandy soils that have been heavilycropped are the most likely of the mineral soils to showa copper deficiency. Organic soils are naturally low inavailable copper, and many field crops will respond tocopper application when grown on these soils. Onceapplied to the soil, copper remains available.Therefore, copper levels may have been improved bypast applications to the soil or by copper fungicidesprays in fields that have been in production for a longtime. The 1 N HCl soil test is a good indicator ofcopper availability in organic soils. No further copperis needed for most field crops once a total of 20pounds of copper per acre have been applied to anorganic soil or the soil test exceeds 20 ppm. Alfalfa,sorghum, Sudangrass, oats and wheat are the cropsmost sensitive to low soil copper. When grown onhigh organic matter sandy soils, these crops may bene-fit from the application of 2 to 4 pounds Cu per acre.Copper sulfate and copper oxide are both effectivesources of copper applied broadcast or in a band.Copper chelates are also good sources of copper andmay actually be slightly more effective than the inor-ganic salts.

Managing Nutrient InputsCommercial fertilizers supply nutrients in forms thatare concentrated, easily handled and applied, readilysoluble and available for plant uptake.

Manures, biosolids and composts are good sources ofplant nutrients. The inorganic forms of nitrogen,phosphorus and potassium are readily available.Nutrients in organic forms are gradually released overtime as they are broken down by microorganisms. Onaverage, 50 percent of the nitrogen in manures will bereleased during the year of application, whereas 80 per-

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Crop Boron Copper Manganese ZincAlfalfa seeding M M L LAlfalfa topdress H M L LBarley L M M LBarley/legume seeding M M M LBeans, dry edible L L H HBrassica forage M M M LBromegrass hay L L M LBuckwheat L L M LCanola L H H LClover seeding M M M LClover hay (topdress) M M M LClover-grass hay M M M LCorn, grain L M M HCorn, silage L M M HCorn, seed L M M HGrass, cool-season L L M LGrass, warm-season L L M LMillet L M H HOats L H H LOats/legume seeding M H H LOats for cover L M M LOrchardgrass hay L L M LPasture, extensive grazing L L M LPasture, intensive grazing L L M LPeppermint L L M LPotato L L H MRye, grain L L L LRye, for cover L L L LRye, silage L L L LSorghum L M H HSorghum-Sudangrass hay L M H MSorghum-Sudangrass haylage L M H MSoybean L L H MSpearmint L L M LSpelts L M M LSugar beet M M H MSunflower M M M MTimothy hay L L M LTrefoil seeding M M M LTrefoil hay M M M LTrefoil, seed production M M M LWheat grain L H H LWheat/legume seeding L H H LResponsiveness is relative to when the soil contains low available levels of the micronutrient.H = highly responsive; M = medium; L = low.

Table 10. Micronutrient responsiveness level for selected field crops.

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cent of the phosphorus and 100 percent of the potassi-um are available. The numbers for biosolids will varywith type and treatment but on average may be similarto those for manures. The composting process tendsto stabilize the nitrogen components so that onlyabout 10 percent of the nitrogen becomes availableduring the application year. Injection or immediateincorporation of manures or biosolids is necessary notonly to reduce odor concerns but also to minimizevolatile nitrogen loss, primarily ammonia. With com-mercial fertilizers, the nutrient content is indicated bythe grade on the label. Values for manures may varyby type and how it is handled. Table 11 gives thenutrient content range that occurred in animalmanures collected from numerous farms. Organicnutrient carriers need to be analyzed to determine thenutrient content. Once this is known, the amount toapply to meet the nutrient requirements of the cropbeing grown can be calculated or the amount of nutri-ent credit to take for manure already applied can becalculated.

in surface water can lead to eutrophication, whichoccurs when elevated nutrient concentrations in watercreate conditions favorable for excess algal and plantgrowth that may result in fish kills, loss of quality forrecreation and increased costs for industries using thatwater.

Phosphorus ManagementPhosphorus is generally an immobile nutrient in soils,especially at low soil test levels. Addition of phospho-rus fertilizer results in P binding to the soil andbecoming slowly available for plant uptake. For low Ptesting soils, broadcast applications are less efficientand will normally result in lower yields than bandapplications. However, broadcast P fertilizer is effectivein building up P soil test levels. Starter fertilizerapplied in a band to the side and below the seed isconsidered the most efficient placement for P. Whensoil test P levels are high, broadcast applications of Pfertilizer are not likely to improve yields but will buildor maintain soil test levels. On soils with high soil testP levels (no fertilizer recommendation), the benefit ofapplying P in a starter fertilizer is not consistent. Onhigh P soils, there is about a 10 percent chance of hav-ing a yield response to starter fertilizer. The probabilityof an economic response depends on the amount ofyield increase and the cost of the starter fertilizer. Theresponse to starter fertilizer on high P soils is morelikely caused by nitrogen than by the additional P. Ifstarter fertilizer containing P is used on a high P soil,apply it at a rate such that the amount of P applied isless than crop removal. For corn (grain), this would beless than 50 pounds P2O5 per acre; for sugar beet, lessthan 30 pounds P2O5 per acre.

Nitrogen ManagementForms of Nitrogen FertilizerNitrate forms of N fertilizer are more subject to lossthan other forms. For example, calcium nitrate andammonium nitrate are readily available sources of N forplants, but the nitrate-N is immediately subject toleaching when added to soil. Therefore, nitrate formsof N should not be used where there is a high leachingpotential. Ammonium forms of N, such as urea, anhy-drous ammonia or urea ammonium nitrate (UAN or28 percent N solution), are preferred sources of N formost crops because they are not subject to immediateleaching when added to soil. Ammonium N must beconverted to nitrate N before it can be leached or den-

Type of Manure N P2O5 K2O N P2O5 K2O

- - - - lb/ton - - - - - - lb/1,000 gal - - Dairy 5-16 2-16 2-31 3-51 2-21 2-58Beef 4-20 1-13 3-29 6-37 1-29 5-30Swine 3-27 1-62 2-18 1-61 1-63 1-49Poultry 1-111 1-96 2-55 35-75 13-91 13-39

Table 11. Range in nitrogen, phosphate andpotash content of various animal manuresshowing farm to farm variation.

Environmental ConsiderationsEnvironmental considerations should be taken intoaccount for all nutrient applications. Nitrogen andphosphorus are the nutrients of most concern. Excessnitrogen applications and certain environmental condi-tions may cause losses of N from the soil to groundwa-ter and air. In sandy soils, excess water from rainfall orirrigation can cause nitrate to leach into groundwater.On finer textured soils, nitrate can be lost to the airthrough denitrification when the soil is warm (above50 degrees F) and wet. Environmental concerns relatedto phosphorus are primarily related to surface waterquality. Phosphorus can be transported to surfacewaters via erosion or surface water runoff. Phosphorus

19


itrified. This conversion to nitrate occurs rapidly underwarm, moist conditions.

Nitrogen can also be lost by volatilization of gaseousammonia from urea or N solutions containing ureawhen they are surface applied and not incorporated.Because the volatilization loss is difficult to assess andrepresents an economic loss to the farmer, all urea-con-taining fertilizers should be incorporated.

Timing of Nitrogen Fertilizer and SplitApplicationsSpring applications of N in the semi-humid regions ofthe United States, including Michigan, have clearlybeen shown to be superior to fall applications (Table12). Climatic conditions from fall to spring significant-ly affect the amount of N lost. Estimates of N lossesfrom fall applications vary from 10 to 20 percent onfine- to medium-textured soils (clay, clay loams andloams) and from 30 to more than 50 percent oncoarse-textured soils (sandy loams, loamy sands andsands). Although applying N in the fall on fine-textured soils may have certain economic benefits, theenvironmental risks of this practice generally outweighthe economic benefits. Fall applications of N are notwarranted in Michigan and should be discontinuedexcept for small applications on fall-seeded wheat.

Yield benefits from split or sidedress N applications forcorn have frequently been observed on coarse-texturedsoils. Although the benefits of sidedress N on fine-textured soils are less frequently seen, there is no ques-tion that sidedress N applications on fine-textured soilscan improve N recovery. Sidedress N applicationsallow time for the grower to adjust N rates on the basisof soil nitrate tests. For these reasons, corn producersshould seriously look at sidedress N applications on allsoil types to improve N efficiency and fine-tune Napplication rates.

Waiting until the corn is well established before apply-ing large amounts of N has two major advantages:nitrate N losses between preplant and sidedress areeliminated, and yield potential can be more accuratelydetermined at sidedress time. Poor stand, poor weedcontrol and/or dry weather at sidedress time are goodreasons for adjusting the yield goal downward andreducing the total amount of N to be applied. Therisk of being unable to sidedress N because of wetweather can be greatly reduced if corn is sidedressedwhen it is 3 to 4 inches tall instead of 1 foot tall. Thebenefits of sidedressing N when the corn is 1 foot tallor higher, rather than 3 to 4 inches tall, are minimal.As high-clearance tractors become more popular, therisk of being unable to sidedress corn due to wetweather is minimized.

Applying nitrogen fertilizer through an irrigation sys-tem offers several advantages for irrigators: N can beapplied when the crop’s demand is greatest, the tech-nique requires little additional energy for application,and the practice is well suited to sandy soils where irri-gation is needed and leaching is a problem. Up to two-thirds of the total N requirements of corn may be sup-plied by this method. Some irrigators choose to applyone-third of their N at planting, one-third at sidedresstime and one-third through the irrigation system.Depending too much on the irrigation system to sup-ply N can have its drawbacks. Rain during the earlygrowing season may prevent crop producers fromusing their irrigation systems. If no previous N wasapplied, this could result in an N shortage early in the

Nitrogen Time of applicationRate1 Fall Spring

lb/A - - - - - - - bu/A - - - - - -Loamy soils (5 experiments)

1002 118 133150 127 154

Irrigated sandy loam soils (6 experiments)100 162 172150 176 181_________________________________________________1Applied as anhydrous ammonia knifed in at 30-inch spacings.2Experiments in 1983 and 1984 received 75 lb/A of nitrogen.

Table 12. Yield of corn as affected by nitrogenrate, time of nitrogen application and soil type(11 experiments from 1977 to 1984).

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season. To eliminate this problem, some crop produc-ers have modified their center pivot systems so they canapply only a very small amount of water in one applica-tion. This allows them to apply N through irrigationregardless of rainfall patterns. It is important not tooverirrigate during the early part of the growing periodin June and July because nitrate concentrations, whichare most subject to leaching loss, are highest duringthis time.

Nitrification InhibitorsCrop producers in many states have successfully usednitrification inhibitors to delay the conversion ofammonium N to nitrate N. Preventing rapid conver-sion of ammonium to nitrate can reduce the amount ofnitrate N that is available for denitrification or leachingearly in the season.

Crop producers should consider using nitrificationinhibitors when it is not feasible to use delayed Napplications, such as by sidedressing or applyingthrough an irrigation system. Nitrification inhibitorscan be beneficial if N applications are made in earlyspring and leaching or denitrifying conditions exist.Nitrification inhibitors are designed to improve nitro-gen use efficiency and minimize N loss. The amountof N used is very crucial to meeting this goal.Nitrification inhibitors are best applied with slightlyless than the recommended N amount. If the rate ofN fertilizer applied is adequate or excessive, no eco-nomic benefits can be expected. Nitrificationinhibitors can improve N recovery when used appropri-ately, but they should not be used as a substitute forfollowing other recommended management practices.

Urease InhibitorsWhen urea is applied on the soil surface, nitrogen canbe lost as volatile ammonia as urea is converted by ure-ase into inorganic N forms. This is of most concernwhen dry urea (46 percent N) or urea-ammoniumnitrate (UAN) solution (which contains 50 percenturea) is applied to no-till fields either preplant or as atopdress. Urease inhibitors slow the conversionprocess, providing more time for the urea to be movedinto the soil by rain or irrigation where the releasedammonia is adsorbed by the soil. Volatile N loss fromurea is of most concern at higher soil and air tempera-tures, especially above 60 degrees F. Therefore, thepotential for loss would be greater for topdress thanfor preplant-applied urea. When urea is incorporated

into the soil, volatile N loss is not a concern. Placingurea or UAN into the soil with a disk-opener or knifeor by tillage will eliminate the concern for volatile Nloss.

Soil Nitrate TestingNitrate is the form of nitrogen that is most available toplants. Soil type, rainfall and temperature greatly affectthe seasonal availability of N to plants. Under wetconditions, N losses can occur by leaching from therooting zone and/or by denitrification from the soil.Denitrification is a microbial process that occurs rapidlywhen soils become water saturated and temperaturesare warm (above 50 degrees F). Denitrification is theconversion of nitrate to some form of nitrous oxide.Nitrate leaching can occur at any soil temperature.Denitrification losses are greatest on fine-textured soilswith poor internal drainage; leaching losses are greateston coarse-textured sandy soils with good internaldrainage. The seasonal availability of nitrate N shouldbe assessed each year and matched to crop needs.

Soil nitrate testing is an excellent and inexpensive wayof evaluating the available N status of your soil.Michigan State University research and demonstrationstudies have shown that corn producers can reducetheir N fertilizer application rate without risk of reduc-ing yields if they use the soil nitrate test. Nitrate test-ing can also help to prevent over-application of N fer-tilizers. The soil nitrate test measures only nitrate N –it does not measure ammonium N or organic N.

Although soil samples may be taken anytime to estab-lish the available N status, the best time to take sam-ples is in June after the soil has warmed up and priorto sidedressing, when it usually contains the greatestamount of nitrate N. The presidedress nitrate test(PSNT) measures both residual nitrate N from the pre-vious year and N that has mineralized (become avail-able) from organic matter, crop residues and manuresduring the spring. Soil samples taken in early spring(April or May) will contain primarily residual nitrate.Although testing in early spring may still be helpful inassessing how much additional N is needed, samplestaken just prior to sidedress time provide the greatestadvantage in determining the appropriate rate of side-dress N.

Manured fields and fields where the previous crop wasa legume will likely contain the most nitrate N. Earlysampling of these fields will not result in the maximum

21


N credit because ammonium N and easily decomposedorganic N will not yet have been converted to nitrateand will not be measured by the test. Therefore, onlythe PSNT is recommended for these fields.

Other fields that show high nitrate N levels are fieldswith medium- and fine-textured soils (loam, clay loamand clay) that have been heavily fertilized in previousyears. Sandy soils, even though heavily fertilized theprevious year, may not show much N carryoverbecause nitrate N can be easily lost by leaching.

PSNT soil samples are best taken shortly before side-dressing (when the corn is 6 to 12 inches tall). At least15, 1-foot soil cores across no more than 20 acresshould be mixed together to make a sample. Samplesshould be dried immediately before sending or keptcold until delivered to a laboratory. N credits areassigned on the basis of the outcome of the nitrate test.Multiply parts per million (ppm) nitrate-N in the soilby 6 to obtain the N credits in pounds per acre to adepth of 2 feet. The conversion factor of 6 assumesthat the amount of N in the second foot of soil is two-thirds of that found in the top foot. This is based onobservations of hundreds of PSNT soil samples takenfrom cornfields in Michigan.

A few caveats for using the PSNT must be stated.First, the PSNT results will be more accurate if lessthan 40 pounds N per acre is applied at or prior toplanting. Second, if the PSNT is less than 5 ppm, noN credit should be taken. Third, if the PSNT isgreater than 25 ppm, no additional N is needed forcorn production.

Stalk Nitrate TestingThe nitrate concentration in the lower part of thecornstalk after black layer formation in the grain canprovide an indication of the efficiency of the nitrogenprogram. Concentrations between 450 and 2,000ppm generally indicate good nitrogen use efficiencywith optimum yields and limited residual soil nitrogen.Values below 450 ppm may indicate very efficient Nuse and optimum yields or a corn crop that ran shorton N with some reduction in yield. Values above2,000 ppm indicate more nitrogen was available thanwas necessary. Maintaining a database of stalk nitratevalues from field to field and from year to year is agood way to fine-tune N management.

Crop Rotations, Forages and Cover CropsCrop rotations can be very beneficial in a successfulcrop production system. For example, a corn-soybeanrotation is preferable to a continuous corn rotationbecause continuous corn requires more N fertilizer toobtain the optimum yield. Some of the yield improve-ment may be due to the rotational effect — i.e., betterdisease, insect and weed control, and improved soiltilth — and some to N fixation by soybeans. Rotationwith other non-legume crops has also been shown toproduce better yields of corn with less N fertilizer.

Cover crops such as oats, barley or rye, seeded aftercrop harvest, can be very beneficial in taking up resid-ual soil N and in preventing wind and water erosion.They protect the soil surface from erosion and therebyreduce the risk of nutrient losses by runoff as solublenutrients or erosion as sediment. Cover crops may alsobe used as green manure crops to take up nitrate andprevent it from being leached to groundwater. Oilseedradish is quite effective at this but must be seeded inAugust or early September. This practice is well suitedto many soils in Michigan and could be used moreeffectively than it is now. One of the keys to utilizingcover crops successfully is to get them established inearly fall so that they have a chance to take up excessnitrate N before winter dormancy and excessive precip-itation occur.

Calibration of EquipmentEvidence of uneven fertilizer distribution due toimproperly adjusted fertilizer spreaders can be seenalmost every year, particularly on winter wheat.Uneven distribution of fertilizer results in overfertiliza-tion in some areas of the field and underfertilization inothers. The result is less than optimum whole fieldyields and potential loss of excess nutrients to surfaceand groundwater.

All fertilizer applicators need to be accurately calibrat-ed. If crop producers are unsure whether the equip-ment they are using is properly calibrated, they shouldrecalibrate the equipment to avoid crop yield loss andpotential risk to the environment. Improving the cali-bration of fertilizer applicators will result in more uni-form distribution of the fertilizer at the proper rate.

22


Suggested Nutrient ManagementPractices for Individual Crops

Corn Grain and Corn SilageNitrogen recommendations are calculated according tothe following equations. Phosphorus and potassiumguidelines are given in tables 13, 14, 15 and 16.Mineral soil

Corn grain = – 27 + (1.36 x YG) – NC

Corn silage = – 25 + (8.33 x YG) – NC

Corn, seed = – 27 + (1.63 x YG) – NC

Organic soilCorn grain = – 67 + (1.36 x YG) – NCCorn silage = – 65 + (8.33 x YG) – NC

where YG = yield goal and NC = nitrogen credit

In Michigan, soils are usually quite cool when much ofthe corn is planted. Placement of fertilizer 2 inches tothe side and 2 inches below the seed at planting canenhance early growth. At this placement, the starterfertilizer can supply up to 40 pounds of nitrogen, 100pounds of phosphate (P2O5) and 100 pounds ofpotash (K2O) per acre. Applying an amount of phos-phate equal to crop removal will help maintain theavailable phosphorus in the soil when the soil test valueis above the critical value of 15 ppm. Inclusion ofphosphorus in starter fertilizer when the soil phospho-rus level is high may enhance early growth but seldomincreases grain yield. Potassium in the starter fertilizeris most beneficial when planting no-till or planting intosoil with a heavy layer of surface residue. Broadcastand incorporate preplant amounts of phosphorus andpotassium required to build up the soil levels (seetables 6 and 8).

Nitrogen may be managed with a combination ofapplication times: preplant, planting time and/or side-dress. Apply preplant nitrogen as close to plantingtime as possible to reduce the risk of nitrogen loss.

Fall application of nitrogen is not recommendedbecause of the potential for leaching loss, even with anitrification inhibitor. Sidedress nitrogen applicationon the basis of a soil nitrogen test when the corn is 6to 12 inches tall provides the most efficient use ofnitrogen inputs. The total amount of nitrogen toapply depends on the expected corn yield (yield goal).Base yield goal on the yield history of the field, such asa five-year running average.

Irrigation of corn influences the fertilizer requirementsbecause it increases the yield potential. Theseincreased requirements are accounted for by thegreater yield goals. A significant portion of the nitro-gen may be applied through the irrigation system.One approach is to apply two-thirds of the nitrogen in

Yield (bu/A) Soil test 140 180

ppm - - - - lb P2O5/A - - - -

5 102 11710 77 92

35 26 3340 0 0

Yield (T/A) Soil test 20 30

ppm - - - - lb P2O5/A - - - -

5 200 20010 189 200

15-30 164 20035 82 12340 0 0

Table 13. Phosphorus recommendations forselected yields of corn.

Table 14. Phosphorus recommendations forselected yields of corn silage.

Soil test to determine lime and nutrient requirements!

15-30 52 67

15-30 164 200

Numbers highlighted are maintenance amounts.

140 bu/A 180 bu/A Soil test CEC 4 8 12 16 4 8 12 16ppm - -- - - - lb K2O/A - - - - - - - - - - - - lb K2O/A - - - - - -

40 92 115 142 173 103 126 153 18480 44 59 78 101 55 70 89 11285 38 52 70 92 49 63 81 10395 38 38 54 74 49 49 65 85

105 38 38 38 56 49 49 49 67115 38 38 38 38 49 49 49 49125 19 38 38 38 25 49 49 49135 0 19 38 38 0 25 49 49

20 T/A 30 T/A Soil test CEC 4 8 12 16 4 8 12 16ppm - -- - - - lb K2O/A - - - - - - - - - - - - lb K2O/A - - - - - -

40 210 233 260 291 272 295 300 30080 162 177 196 219 224 239 258 28185 156 170 188 210 218 232 250 27295 156 156 172 192 218 218 234 254

105 156 156 156 174 218 218 218 236115 156 156 156 156 218 218 218 218125 78 156 156 156 109 218 218 218135 0 78 156 156 0 109 218 218

23


some combination of preplant, planting time and/orsidedress applications and the remainder through theirrigation system.

SoybeansPhosphorus and potassium recommendations are givenin tables 17 and 18.

Soybean is a legume that can meet its nitrogen need bysymbiotic fixation of atmospheric nitrogen. In general,soybeans will not benefit from supplemental nitrogenapplication. Soybeans are widely grown in Michigan.Most fields have adequate indigenous populations ofthe appropriate Bradyrhizobia bacteria strains thatcause effective nodulation of soybean roots and nitro-gen fixation. Where soybeans have not been grownrecently, inoculation of the soybean seed with soybean-specific Bradyrhizobia strains is essential for effective

nitrogen fixation.

Soybeans are more sensitive to fertilizer placement andrate than corn. Starter fertilizer placed 2 inches to theside and 2 inches below the seed can contain up to100 pounds of phosphate (P2O5) and 60 pounds ofpotash (K2O) per acre. Placement of fertilizer withthe seed may cause serious injury and reduced plantstands. When soybeans are drilled (7- to 10- inchspacing), broadcast and incorporate all the phosphateand potash prior to planting. For no-till soybeans, usea band-placed starter fertilizer or broadcast therequired fertilizer prior to planting. On lakebed soilsand dark-colored soils where the soil pH is above 6.5,manganese application will usually improve soybeangrowth and yields. Include 2 pounds of manganese (orthe recommended amount based on a soil test) in the

Table 15. Potassium recommendations for selected yields of corn.

Table 16. Potassium recommendations for selected yields of corn silage.

Numbers highlighted are mainenance amounts.

Soil 40 bu/A 60 bu/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A - - - - - lb K2O/A - -

40 110 133 160 191 138 161 188 20080 62 77 96 119 90 105 124 14785 56 70 88 110 84 98 116 13895 56 56 72 92 84 84 100 120105 56 56 56 74 84 84 84 102115 56 56 56 56 84 84 84 84125 28 56 56 56 42 84 84 84135 0 28 56 56 0 42 84 84

Yield (cwt/A) Soil test 20 30

ppm - - - - lb P2O5/A - - - -

5 74 8610 49 61

15-30 24 3635 12 1840 0 0


ppm - - - - lb P2O5/A - - - -

5 82 9810 57 73

15-30 32 4835 16 2440 0 0

24


starter fertilizer or apply one or two applications of 1to 2 pounds Mn per acre to the foliage. Broadcastapplications made to the soil are not effective.

Dry Edible (Field) BeansPhosphorus and potassium recommendations are givenin tables 19 and 20.

Dry beans, like soybeans, are legumes and can fixnitrogen. Nitrogen fixation in dry bean can be unreli-able, however, because of environmental conditionsand variability between varieties. Therefore, applying40 to 60 pounds N per acre is recommended toachieve maximum yield. Apply 60 pounds N per acrefor beans grown in narrow rows (less than 23 inches)and for colored beans grown under irrigation. Forbeans grown with less intense management systems,apply 40 pounds N per acre. Applying excess nitrogencan delay bean maturity and may create greater poten-

tial for white mold if the crop canopy is dense.

Dry beans are sensitive to low levels of available zinc.Providing adequate amounts of zinc fertilizer, if need-ed, is important because even mild zinc deficiency candelay maturity. Use a soil test to determine availablezinc levels and calculate the amount to apply from theequation: Zn rec. (lb/A) = (5.0 x pH) – (0.4 x STppm) – 32. In the absence of a soil test, apply 1pound Zn per acre if the previous crop was sugar beetsor if the soil pH is above 6.5.

Dry beans do not tolerate fertilizer applied with theseed. Up to 40 pounds of nitrogen, all of the phos-phate and 60 pounds of potash may be included in astarter fertilizer placed in a band 2 inches to the sideand 2 inches below the seed. Before planting, broad-cast and incorporate any additional fertilizer that isneeded. Additional nitrogen may also be sidedressedtwo weeks after planting.

Bean yield may be affected by nutrient managementand cropping systems. Dry beans grown after sugarbeets often experience zinc deficiency that results indelayed maturity and reduced yield. Dry beans rely ona symbiotic relationship with mycorrhizal fungi to assistthe plant in taking up nutrients. Sugar beets do nothost these fungi. Reduced numbers of mycorrhizaeafter sugar beets result in zinc deficiency because thebean plant can not take up enough zinc on its own.

Table 17. Phosphorus recommendations for selected yields of soybean.

Table 18. Potassium recommendations for selected yields of soybean.

Table 19. Phosphorus recommendations forselected yields of dry edible beans.



Yield (bu/A) Soil test 60 90ppm - - - - lb P2O5/A - - - -

5 123 13410 98 10915 73 8420 48 59

25-40 23 3445 11 1750 0 0

Soil 20 cwt/A 30 cwt/A test CEC 4 8 12 16 4 8 12 16ppm - - lb K2O/A - - - - lb K2O/A - -

40 86 109 136 167 102 125 152 18380 38 53 72 95 54 69 88 11185 32 46 64 86 48 62 80 10295 32 32 48 68 48 48 64 84

105 32 32 32 50 48 48 48 66115 32 32 32 32 48 48 48 48125 16 32 32 32 24 48 48 48135 0 16 32 32 0 24 48 48

25


Dry beans are more sensitive to soil compaction thansome other crops, particularly soybean, so take care toavoid soil compaction after primary tillage.

Small Grains Wheat, Barley, Oats, Rye, CanolaNitrogen recommendations are given according to thefollowing equations:

Mineral soil: N rec. = A + (B x YG)Organic soil: N rec. = Mineral soil N rec. – 30

where:Barley A = – 12 and B = 0.8Canola A = 50 and B = 0.8Oats A = 0 and B = 0.4Rye A = 0 and B = 0.7Wheat A = – 13 and B = 1.33

Phosphorus and potassium recommendations for wheatand barley are given in tables 21, 22, 23 and 24.Phosphorus and potassium recommendations for oatsare about 10 pounds P2O5 per acre and 5 pounds K2Oper acre more than those for barley at the same yieldlevel. Recommendations for the other cereal grainscan be calculated from the equations on pages 9 – 11and the information in tables 7 and 9.

Many grain drills deliver fertilizer in direct contact orclose proximity with the seed. Large amounts of fertil-izer may adversely affect germination and seedlingestablishment, especially if the soil is dry. To minimizethe potential for injury, apply no more than 100pounds per acre of nutrients (N + P2O5+ K2O) in con-tact with the seed in sandy soils and no more than 140pounds per acre in fine-textured soils. Broadcast andincorporate preplant fertilizer required in excess of thatapplied with the drill. The alternative is to broadcast

and incorporate all the required fertilizer nutrientsprior to seeding.

For winter wheat or barley, apply no more than 25pounds of N per acre in the fall. This may be includedin the preplant broadcast or planting time fertilizer. Inthe spring prior to green-up, topdress additional nitro-gen based on yield potential of the field. For high-yielding wheat varieties and sites, this is usually 80 to100 pounds per acre. Another option is to split thenitrogen between pre-green-up and Feeke’s stage 5 or6. Wheat does best following soybeans, dry ediblebeans or silage corn.

For rye grown for grain, apply 40 pounds N per acreprior to spring green-up. No nitrogen is recommend-ed for rye grown as a cover crop. For spring-seededgrains, barley, oats, millet and buckwheat, broadcastand incorporate the required amounts of nitrogen,phosphorus and potassium prior to seeding. On slight-ly acidic sandy soils, foliar application of 1 to 2 poundsMg per acre may be beneficial if the soil magnesiumlevel is marginal or low (< 35 ppm).

Wheat, oats and barley grown on lakebed soils anddark-colored soils where the soil pH is above 6.5 maybenefit from manganese application. Manganese isbest applied in the planting time fertilizer or as a sprayon the actively growing foliage. Manganese that isbroadcast and incorporated is readily bound intounavailable forms. Test these soils for manganese andapply recommended amounts.

Table 20.Potassium recommendations forselected yields of dry beans.

Table 21. Phosphorus recommendations forselected yields of wheat.



Soil 60 bu/A 90 bu/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A - - - - - - lb K2O/A - - -

40 76 99 126 157 87 110 137 16880 28 43 62 85 39 54 73 9685 22 36 54 76 33 47 65 8795 22 22 38 58 33 33 49 69105 22 22 22 40 33 33 33 51115 22 22 22 22 33 33 33 33125 11 22 22 22 17 33 33 33135 0 11 22 22 0 17 33 33

26



ppm - - - lb P2O5/A - - -

5 69 8010 44 55

15-30 19 3035 10 1540 0 0

Soil 50 bu/A 80 bu/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A - - - - - - lb K2O/A - -

40 67 90 117 148 74 97 124 15580 19 34 53 76 26 41 60 8385 13 27 45 67 20 34 52 7495 13 13 29 49 20 20 36 56105 13 13 13 31 20 20 20 38115 13 13 13 13 20 20 20 20125 7 13 13 13 10 20 20 20135 0 7 13 13 0 10 20 20

For oats add 5 lb/A.

Table 22. Phosphorus recommendations forselected yields of barley.

Table 23. Potassium recommendations forselected yields of wheat.

Table 24. Potassium recommendations forselected yields of barley.

Sugar BeetsNitrogen recommendations are calculated according to the follow-ing equations: N rec. = 4 x YP

when corn is the previous crop: N rec. = (4 x YP) + 30where YP is yield potential

Phosphorus and potassium recommendations for sugarbeets are given in tables 25 and 26.

Nitrogen management in sugar beet production is crit-ical to maximize sugar yield. Nitrogen is needed toproduce high yields of beets, but too much nitrogenreduces the sugar quality of the harvested beet. Sugaryield is maximized by balancing high yield and quality.In general, 80 to 100 pounds of N per acre will maxi-mize yield and sugar quality. The majority of researchthat went into developing this recommendation was forbeets following beans. When beets are grown aftercorn, increase the nitrogen application rate by 30pounds N per acre. It is likely that additional nitrogenis needed for beets after corn because corn is not alegume. Research results over the past two years sup-port this recommendation. Sugar beets need a majori-ty of the N early in the season to obtain canopy clo-sure; then relatively small amounts are required forcanopy maintenance. Having adequate N early in theseason is important for the crop to get off to a goodstart. Starter fertilizers (2 x 2 band placement) shouldprovide 30 to 40 pounds N per acre. Alternatively, thenitrogen can be applied prior to planting. However,some experiences suggest that, to reduce the risk offertilizer adversely affecting germination, apply pre-plant no more than 50 pounds N per acre.

Beets generally will not respond to phosphorus fertiliz-er when soil test values are greater than 30 ppm (60pounds P per acre). On high P soils, phosphorus isnot needed in a starter fertilizer. If one wishes to use astarter fertilizer containing P2O5, then the amount ofP2O5 applied should be less than crop removal(approximately 30 pounds P2O5 per acre). Beets aresensitive to low levels of available manganese, particu-larly when the soil pH is higher than 6.5. Use a soiltest to determine available manganese levels and theamount of manganese to apply. Manganese applicationsare most effective in starter fertilizers. Foliar applica-tions of manganese (1 pound per acre) can be used toremediate deficiencies that appear after crop establish-ment.

Sugar beets grow best when the soil pH is between 6.0and 7.0. Preliminary research in another beet growingregion of the United States suggests that when soil pHis higher than 6.5, the incidence of root diseases islower.



ppm - - - - lb P2O5/A - - - -

5 126 13610 101 11115 76 8620 51 71

25-40 26 3645 13 1850 0 0

27


Forage CropsLegumes Phosphorus and potassium recommendations for alfalfaand clover are given in tables 27, 28, 29, 30 and 31.

For legumes, be sure to adjust the soil pH to 6.5 orabove by applying the appropriate rate of limestone.This is best done by applying and incorporating thelime about 6 to 12 months prior to seeding. Whenno-till seeding legumes on erosive sites, broadcast thelime without incorporation. Broadcast and incorporatethe required phosphate and potash during seedbedpreparation or apply it through the seeder. Base rateson soil tests. When fertilizer is applied with the seed-ing unit, allow the seed to fall on the top of the soilabove the fertilizer band and to be firmed in no morethan 1⁄2 inch deep with press wheels or cultipacker.Fertilizer placed 1 to 11⁄2 inches below the seed maysupply all the phosphorus and up to 150 pounds K2Oper acre. For fertilizer placed directly with the seed,

limit the amounts to 100 pounds P2O5 and 50 poundsK2O per acre. Planting time nitrogen is not necessaryfor legume seedings, but be sure to inoculate the seedwith the appropriate strains of Rhizobia before plant-ing. Including 20 pounds of nitrogen per acre in thebroadcast or planting time fertilizer may improveseedling establishment in cool soils but generally pro-vides little benefit.

Legumes are more difficult to establish when using asmall grain as a nurse crop rather than by clear seeding.The small grain nurse crop should be harvested assilage to reduce competition with the new legumeseeding. The fertilizer applied for the small grain issufficient to carry the legumes through the first season.Topdress the legume with appropriate amounts ofphosphorus and potassium after the small grain nursecrop is removed as silage or after the first cutting of aclear seeding.

Boron is needed annually on sandy soils (CEC < 8.0)at a rate of 2 pounds per acre. Fine-textured soils cansupply adequate boron, so boron applications have notproven beneficial. Where needed, apply boron in thetopdressing fertilizer. Legumes remove large amountsof potassium (45 to 60 pounds K2O per ton) from thesoil. To replace potassium removed by the crop, top-dress potash (K2O) in the spring when the crop is dor-mant or after a harvest. Fall application is acceptableon all soils except loamy sands and sands, where signifi-cant leaching may occur. It is suggested to limit singleapplications to no more than 300 pounds K2O peracre.

Soil 20 T/A 28 T/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A - - - - - - lb K2O/A - - -

40 120 143 170 201 146 169 196 22780 72 87 106 129 98 113 132 15585 66 80 98 120 92 106 124 14695 66 66 82 102 92 92 108 128

105 66 66 66 84 92 92 92 110115 66 66 66 66 92 92 92 92125 33 66 66 66 46 92 92 92135 0 33 66 66 0 46 92 92

Table 25. Phosphorus recommendations forselected yields of sugar beets.

Table 26. Potassium recommendations forselected yields of sugar beets.

Yield (T/A) Soil test 4 6 8

ppm - - - - - - lb P2O5/A - - - - -

5 152 178 20010 127 153 17915 102 128 15420 77 103 129

25-40 52 78 10445 26 39 5250 0 0 0

Table 27. Phosphorus recommendations for selected yields of alfalfa.




ppm - - - - lb P2O5/A - - - -

5 114 15310 89 12815 64 103

20-35 39 7840 20 3945 0 0


40 174 197 224 255 294 300 300 30080 126 141 160 183 246 261 280 30085 120 134 152 174 240 254 272 29495 120 120 136 156 240 240 256 276

105 120 120 120 138 240 240 240 258115 120 120 120 120 240 240 240 240125 60 120 120 120 120 240 240 240135 0 60 120 120 0 120 240 240


40 254 277 300 300 300 300 300 30080 206 221 240 263 300 300 300 30085 200 214 232 254 300 300 300 30095 160 200 216 236 300 300 300 300105 120 160 200 218 300 300 300 300115 80 120 160 200 160 300 300 300125 40 80 120 160 80 160 300 300135 0 40 80 120 0 80 160 300


ppm - - - - lb P2O5/A - - - -

5 105 13510 80 11015 55 85

20-35 30 6040 15 3045 0 0

Table 28. Phosphorus recommendations for selected yields of clover hay.

Table 29. Phosphorus recommendations forselected yields of clover-grass hay.

Table 30. Potassium recommendations forselected yields of alfalfa hay.

Table 31. Potassium recommendations forselected yields of clover and clover-grass hay.


Grass Hay or PastureThe nitrogen recommendation for a grass hay and foran intensively grazed (rotational grazing) grass pastureis 150 to 200 pounds N per acre. Nitrogen should beapplied in split applications of 40 to 50 pounds N peracre at green-up, June 1, August 1 and September 1.Phosphorus and potassium recommendations are pre-sented in tables 32 and 33 for bromegrass.Phosphorus recommendations for other grasses aresimilar to those of bromegrass, but potassium recom-mendations are different because the various grassestake up different amounts of potassium (see Table 3).

When grass is seeded for hay or pasture, the fertilizermay be broadcast and incorporated prior to seeding orapplied at the time of seeding. Base the amounts toapply on a soil test. When fertilizer is applied with theseed, limit the total amounts of nutrients (N + P2O5 +K2O) to 100 pounds per acre on sandy soils and 140pounds per acre on fine-textured soils. Broadcast andincorporate any additional amounts of phosphate andpotash. Include 30 to 40 pounds nitrogen per acre inthe preplant or planting time fertilizer.

For established grass hay, annually topdress 200pounds of nitrogen per acre in split applications plusmaintenance amounts of phosphate and potash. Forgrass-legume hay with more than six legume plants persquare foot, no additional nitrogen is needed. As thepercent legume decreases, the need for nitrogenincreases. With a legume stand of less than 40 percent(fewer than three plants per square foot), apply 100pounds of nitrogen per acre.

28

Numbers highlighted are maintenance amounts.Maximum recommendation for a single application is 300 lb.K2O/A.


29


Grass PastureAnnually topdress with nitrogen plus maintenanceamounts of phosphate and potassium. Apply, in splitapplications, 150 pounds N per acre for intensivelygrazed pastures (rotational grazing) and 200 poundsN per acre for extensively grazed pastures. When pas-tures contain more than 40 percent legume, additionalnitrogen is not recommended.

Brassicas for ForageSeveral of the brassica species (kale, rape, swedes,turnips) can be used as a fall forage crop to be grazed.They are frequently planted after the harvest of smallgrains. Apply a total of 100 pounds of nitrogen peracre. Broadcast and incorporate the recommendedamounts of phosphorus and potassium prior to plant-ing.

Grass Waterways and Critical AreasGrass waterways, highly erodible soil and other criticalareas need good fertility to maintain a dense, uniformcover through the year. Because there will be no cropremoval, the amount of fertilizer to apply will be thatfor building the soil test values up to the critical level.Broadcast and incorporate 40 pounds N per acre andthe required amounts of phosphate (P2O5) and potash(K2O) prior to seeding, or, if the crop is already estab-lished, broadcast the fertilizer. To maintain vigor,annually topdress with up to 25 pounds N per acre.

Conservation Reserve The Conservation Reserve Program (CRP) providescost sharing for establishment of long-term, resource-conserving ground covers to improve water quality,control soil erosion and enhance wildlife habitat.Native cool- or warm-season grasses alone or in combi-nation with a legume are frequently seeded for CRPplantings. For establishment and maintenance of long-term vegetative covers, adjust the soil pH to above 6.0prior to seeding. Required soil phosphorus and potas-sium levels are lower than those for forage hay produc-tion because there is no removal of biomass. Apply theamounts of phosphorus and potassium needed to buildthe soil level to the critical level (10 ppm P, 95 ppmK). No nitrogen is recommended for establishment ofwarm- or cool-season grasses with or without alegume. Studies have shown that nitrogen applicationincreases weed competition. No maintenance fertiliza-tion is needed once ground cover is established


ppm - - - lb P2O5/A - - -

5 102 12810 77 103

15-30 52 7835 26 3940 0 0

Soil 4 T/A 6 T/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A- - - - - - lb K2O/A - - -

40 258 281 300 300 300 300 300 30080 210 225 244 267 300 300 300 30085 204 218 236 258 300 300 300 30095 204 204 220 240 300 300 300 300

105 204 204 204 222 300 300 300 300115 204 204 204 204 300 300 300 300125 102 204 204 204 153 300 300 300135 0 102 204 204 0 153 300 300

Table 32. Phosphorus recommendations forselected yields of bromegrass hay.

Table 33. Potassium recommendations forselected yields of bromegrass hay.

because nutrients taken up by the plants will be recy-cled as the biomass dies and decomposes.

PotatoRecommended nitrogen can be calculated as follows:N rec = 150 + ((YG - 300) x 0.3) where YG is yield goal in cwt/A

For Russet Burbank, Snowden and other late-maturingvarieties, increase the nitrogen recommendation by 40pounds N per acre. Phosphorus and potassium recom-mendations are given in tables 34 and 35. Apply up to60 pounds of nitrogen, all of the phosphorus and upto 100 pounds of potash (K2O) per acre in starterbands 2 inches to the side and level with or slightlybelow the seed pieces. Placing bands on both sides ofthe seed pieces is more effective than banding on justone side. Prior to planting, broadcast and incorporatepotash in excess of the amount applied in the fertilizerbands. Fall application of potassium on sandy andorganic soils is not recommended because of thepotential for leaching loss. Incorporating a legume

Numbers highlighted are maintenance amounts.Maximum recommendation for a single application is 300 lb.

Soil 340 cwt/A 450 cwt/A test CEC 4 8 12 16 4 8 12 16ppm - - - lb K2O/A - - - - - - lb K2O/A - - -

40 274 297 300 300 300 300 300 30080 226 241 260 283 289 300 300 30085 220 234 252 274 283 297 300 30095 220 220 236 256 283 283 299 300105 220 220 220 238 283 283 283 300115 220 220 220 220 283 283 283 283125 110 220 220 220 142 283 283 283135 0 110 220 220 0 142 283 283145 0 0 110 220 0 0 14 283155 0 0 0 110 0 0 0 142 165 0 0 0 0 0 0 0 0

30


Yield cwt/A Soil test 350 400 450

ppm - - - - lb P2O5/A - - - -

20 245 252 25840 145 152 158

60-100 45 52 58120 9 10 11140 0 0 0

Table 34. Phosphorus recommendations forselected yields of potato.

Table 35. Potassium recommendations forselected yields of potato.

cover crop or animal manure can significantly reducethe amount of supplemental nitrogen needed.Nitrogen broadcast prior to planting has an increasedrisk of loss by leaching. Nitrogen applied after plant-ing is usually used more efficiently than nitrogenapplied preplant. It is best to supply needed nitrogenthrough a combination of applications at planting timeand hilling and through irrigation. (For more informa-tion on nutrient management of potatoes, see MSUExtension bulletin E 2779.) After harvest, establish acover crop to take up any residual nitrogen and to pro-tect against wind erosion.

Manganese may be needed when the soil pH is above6.5 on mineral soils and above 5.8 on organic soils.Use a soil test to determine the amount of Mn needed.Include the required amount of manganese in thestarter fertilizer or spray the foliage with 1 to 2 poundsMn per acre at least twice during active growth.




MSU is an affirmative-action equal-opportunity institution. Michigan State University Extension programs and materials are open to all without regardto race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status. ■ Issued in further-ance of Extension work in agriculture and home economics, acts of May 8 and June 20, 1914, in cooperation with the U.S. Department of Agriculture.Margaret A. Bethel, Extension director, Michigan State University, E. Lansing, MI 48824. ■ This information is for educational purposes only.Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. This bulletin

becomes public property upon publication and may be printed verbatim with credit to MSU. Reprinting cannot be used to endorse or advertise a commercial product or com-pany.

New 5/04 (Replaces E550)-3M-KMF/DP, $3.40, for sale only.

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