Table 1. Soil pH Recommended for Various Crops on Various Soils.
Mineral soils with subsoil pH
Organic
Crop > pH 6 <pH 6 soils
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--------- pH ---------
Alfalfa 6.5 6.8 5.3
Other forage
legumes 6.0 6.81 5.3
Corn 6.0 6.5 5.3
Soybeans 6.0 6.5 5.3
Small grains 6.0 6.5 5.3
Other crops 6.0 6.5 5.3
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1 Birdsfoot trefoil should be limed to pH 6.0.

Soil pH should be corrected by liming when the pH in the zone of sampling falls 0.2 to 0.3 pH units below the recommended level. The rates of application given in Table 2 are based on the lime test index obtained using the SMP-buffer lime requirement test and are applicable to an 8-inch depth. For no-till and established forages, lime recommendations are based on a 0- to 4-inch depth, so the rates of application should be one-half the values given in Table 2. These rates are for agricultural ground limestone with a neutralizing value of 90 percent. They should be adjusted if other types of liming material are used. To adjust for a liming material with a different neutralizing value (nv)., multiply the lime recommendation given in the table by 0.90 and divide by the new neutralizing value.

Example: Lime recommendation = [(tons per acre x 0.90) / 0.80] if nv is 80 percent.

Table 2. Tons of Agricultural Limestone Needed to Raise the Soil pH to the Desired pH Level Based on the SMP Lime Test Index and an Incorporation Depth of 8 Inches.
Desired pH levels
__________________________________________________ ___________
Lime
test Mineral soils Organic soils
--------------- ---------------
index1 6.8 6.5 6.0 Soil pH 5.3
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tons agricultural limestone/acre2 tons/acre
68 1.4 1.2 1.0 5.2 0.0
67 2.4 2.1 1.7 5.1 0.7
66 3.4 3.0 2.4 5.0 1.3
65 4.5 3.8 3.1 4.9 2.0
64 5.5 4.7 3.9 4.8 2.6
63 6.5 5.6 4.6 4.7 3.2
62 7.5 6.5 5.3 4.6 3.9
61 8.6 7.3 6.0 4.5 4.5
60 9.6 8.2 6.7 4.4 5.1
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1 Lime test index is the SMP buffer pH x 10.

2These values are based on agriculture limestone with a
neutralizing value of 90 percent (Indiana RNV = 65, Ohio TNP = 90+).
Adjustments in the application rate should be made for liming
materials with different particle sizes, neutralizing values and
depths of incorporation

The relative availability of the liming material is also affected by the lime particle size. For information on adjusting lime recommendations because of differences in lime particle size, see in-state publications.

Lime rates also should be adjusted for other depths of incorporation. To adjust for other depths, divide by 8 and multiply by the new incorporation depth.

Example:Lime recommendation = [(tons per acre / 8) x 10] if incorporation depth is 10 inches.

Lime recommendations (LR) are calculated from the lime test index (LTI) for mineral soils and the soil pH for organic soils using the following formulas and rounding to the nearest tenth of a ton:

Mineral soils
to pH 6.8: LR = 71.4 - 1.03 x LTI
to pH 6.5: LR = 60.4 - 0.87 x LTI
to pH 6.0: LR = 49.3 - 0.71 x LTI
Organic soils
to pH 5.3: LR = 32.9 - 6.31 x soil pH

These rates should raise soil pH to the desired pH level, but the exact pH is not always achieved. Applications of less 7, than 1 ton/acre often may not be practical and will not appear in computer-generated recommendations. When the recommendation is for 2 tons/acre or less, the application can be made any time in a cropping sequence. When the lime recommendation exceeds 4 tons per acre, apply the lime in a split application - i.e., half before plowing and half after plowing. Do not apply more than 8 tons of lime in one season. Large applications of lime without thorough mixing may cause localized zones of high alkalinity, reducing the availability of some essential nutrients. If the soil test indicates more than 8 tons per acre are required, retest two years after the application to see if more lime is needed.

Surface applications of urea forms of, N fertilizer are not recommended on fields where lime has been surface applied recently. The potential N loss by ammonia volatilization is high when urea reacts with unincorporated lime. Urea forms of N should not be surface applied within one year of the lime application. Surface applications of ammonium nitrate, ammonium sulfate, or injected 28 percent N or anhydrous ammonia are preferred when lime is not incorporated.

WEAKLY BUFFERED SOILS
Because sandy soils are often weakly buffered, there is concern about lime requirements determined by the SMP lime test. These soils may have a soil water pH below the desired pH range for optimum crop growth but the lime index test does not indicate a need for lime. This occurs because weakly buffered soils do not have sufficient capacity to lower the pH of the SMP buffer solution. When this situation occurs, growers may want to consider using 1 ton of lime per acre when the soil water pH is more than 0.3 pH units below the desired soil pH and 2 tons per acre when the soil water pH is more than 0.6 pH units below the desired soil pH.