University of Missouri Extension

WQ310, Reviewed July 1995

Spreading Dairy Waste With Lab Analysis and With Soil Tests

Charles D. Fulhage and Donald L. Pfost
Department of Agricultural Engineering

A primary need and concern for most confinement livestock producers is managing manure so that groundwater and surface water are protected and regulatory requirements are fulfilled. This objective is usually accomplished by applying manure to the land in such a manner that the potential polluting nutrients (N, P, K and organic matter) are used by the soil-plant complex and are not allowed to enter the groundwater/surface water infrastructure.

Manure is a fertilizer resource

Manure should be viewed as a fertilizer resource and managed similarly to commercial fertilizer in the fertility program. The occasional practice of meeting fertility requirements with commercial fertilizer, then applying manure in addition "for good measure," can easily lead to adverse impacts on water quality. In general, Missouri waste application regulations are based on the rate of nitrogen application. With this scenario, the phosphorus and potash applied may greatly exceed crop needs. Therefore, optimum use of plant nutrients may necessitate applying less nitrogen from waste than the crop needs and buying supplemental nitrogen to balance crop needs.

Applying phosphorus to fields with a Bray 1-P test level exceeding 800 pounds per acre may aggravate surface water quality problems

It is highly recommended that a representative sample of dairy waste be analyzed for nutrient values immediately prior to spreading, in addition to soil tests, before determining the land application rate. The purpose of this publication is to provide guidance for application of waste with the benefit of a lab analysis and a soil test. Other publications in this series address application of dairy waste with other scenarios.

Managing manure as a fertilizer

Unlike commercial fertilizers, manure is a highly variable substance, even within a given animal specie, and variations of 50 percent to 100 percent among test samples are not unusual. Other management considerations peculiar to livestock operations, such as lagoon pumping in the fall to provide storage during winter and spring months, or manure storage tank emptying at whatever intervals are required to prevent overflow, dictate different management than commercial fertilizer that can just be "ordered and spread."

In contrast to commercial fertilizer, manure has the potential for nutrients (primarily nitrogen in the form of ammonia) to be lost to the atmosphere after field spreading. Table 1 shows the available ammonia nitrogen as a function of time until incorporation into the soil. Table 2 lists the percent of available organic nitrogen available with time. Table 3 gives the percent of various nutrients available in the growing season after application.

Table 1
Manure ammonia-nitrogen available by days until incorporated into the soil (unavailable portion is lost to the atmosphere)

Days until incorporation Percent of ammonia-N available for crops
0 to 2 80
2 to 4 60
4 to 7 40
more than 7 20

Table 2
Manure organic nitrogen available by year

Manure applied Percent of organic-N available during current year
Current year 40 to 60
1 year ago 10
2 years ago 5
3 years ago 5

Table 3
Other minerals and micronutrients available in manure

Nutrient Percent of Ammonia-N available in growing season
P 80
K 100
S, Mn, Cu, Zn 80
Ca, Mg 100

A soil test report (pictured in the printed version of this guide) gives the recommended nutrient application rates for a yield goal of 3 tons per acre of fescue hay. This publication details a procedure for estimating the amount of manure to apply to meet the soil test recommendations for nitrogen by applying dairy waste with a known nutrient analysis. A blank "Manure fertility worksheet" is included for actual applications.

Note
This approach cannot be used if the Department of Natural Resources has issued a letter of approval based on the "conservative approach" of applying not more than 100 pounds of nitrogen per year, regardless of the crop and the production level of the crop.

Examples

A fescue hayfield (soil-plant filter) is available for receiving dairy waste. The accompanying soil test contains fertilizer recommendations for a yield goal of 3 tons of fescue hay per year from the soil-plant filter area. From the soil test, the following nutrient applications are recommended:

Given this information and the laboratory analysis of the dairy waste, how many inches of lagoon effluent, how many gallons per acre of liquid manure (slurry) and how many tons per acre of solid manure should be applied to meet the nitrogen needs of the fescue? Tables 4, 5 and 6 outline previous years' application rates and analyses for solid, liquid and lagoon effluent.

Table 4
Laboratory analysis for solid manure and rate of past application

Nutrient Nutrient level, pounds per ton
This year 1 year ago 2 years ago 3 years ago
Total N 10 8 11 7
NH4-N 5 4 5 3
Organic N 5 4 6 4
P2O5 (phosphate) 4 3 5 4
K2O (potash) 11 8 12 9
Application, tons ? 21 19 22

Table 5
Laboratory analysis for liquid manure and rate of past application

Nutrient Nutrient level, pounds per K-gallons
This year 1 year ago 2 years ago 3 years ago
Total N 30 24 33 21
NH4-N 10 8 10 7
Organic N 20 16 23 14
P2O5 (phosphate) 14 11 13 14
K2O (potash) 28 21 31 23
Application, K-gal1 ? 7 6 7
1K-gal = 1,000 gallons, e.g. 6 K-gal = 6,000 gallons

Table 6
Laboratory analysis for lagoon effluent and the rate of past application

Nutrient Nutrient level, pounds per K-gallons
This year 1 year ago 2 years ago 3 years ago
Total N 78 66 70 55
NH4-N 52 44 45 30
Organic N 26 22 25 25
P2O5 (phosphate) 41 33 39 31
K2O (potash) 130 110 122 106
Application, inches1 ? 2.0 2.5 3.1
1One acre-inch = 27,154 gallons

Assume that the waste applied as solid or liquid will not be incorporated into the soil, therefore the loss of ammonia-nitrogen will be 80 percent. Assume that the waste applied as lagoon effluent will be incorporated into the soil within two days after application (by infiltration into the soil), therefore the loss of ammonia-nitrogen will be only 20 percent.

Solid manure

The laboratory analysis (Table 4) for solid manure is available for present and past years with the rate of application for the past three years. Given this information, complete the "Solid manure worksheet" to determine the proper application rate.

Liquid manure (slurry)

he following laboratory analysis (in Table 5) for liquid manure (slurry) is available for present and past years with the rate of application for the past three years. Complete the "Liquid manure worksheet" to determine the proper application rate.

Lagoon effluent

The laboratory analysis for lagoon effluent, appearing in Table 6, for is available for present and past years with the rate of application for the past three years. Complete the "Lagoon effluent worksheet" to determine the proper application rate.

Manure fertility worksheet

  1. Crop nutrient requirements (from soil test)
    Crop ________
    Yield ________
    N, pounds per acre ________
    P2O5, pounds per acre ________
    K2O, pounds per acre ________
  2. Available ammonia (NH4-N) nitrogen (from lab test).
    Lagoon
    pounds NH4-N x percent available = pounds NH4-N per acre-inch
    Slurry
    pounds NH4-N per K-gal x percent available = pounds NH4-N per K-gal
    Solid
    pounds NH4-N per ton x percent available = pounds NH4-N per ton
    (Percent available from Table 1)

Note
K-gal = 1,000 gallons

  1. ________ x ________ = __________
  2. Nitrogen available from this year's organic fraction (from lab test).
    Lagoon
    pounds N per acre-inch x percent available = pounds N per acre-inch
    Slurry
    pounds N per K-gal x percent available = pounds N per K-gal
    Solid
    pounds N per ton x percent available = pounds N per ton
    (Percent available from Table 2)
    ________ x ________ = __________
  3. Residual nitrogen available from previous year's organic fraction.
    Lagoon
    inches x pounds N per acre-inch. x percent available = pounds N per acre
    Slurry
    K-gal per acre x pounds N per K-gal x percent available = pounds N per acre
    Solid
    tons per acre x pounds N per ton x percent available = pounds N per acre
    (Percent available from Table 2)
    1 year ago: ________ x ________ x ________ = __________
    2 years ago: ________ x ________ x ________ = __________
    3 years ago: ________ x ________ x ________ = __________
    Total = __________
  4. Manure application rate.
    (crop N requirement, line 1) - (residual N, line 4) -
    (available NH4-N, line 2) + (available organic fraction, line 3)
    = application rate
    (______) - (______)
    (_____) + (______)
    = ____________
  5. Phosphorus available at calculated application rate for nitrogen.
    Lagoon
    inches x pounds P per acre-inch x percent available = pounds P per acre
    Slurry
    K-gal per acre x pounds P per K-gal x percent available = pounds P per acre
    Solid
    tons per acre x pounds P per ton x percent available = pounds P per acre
    (Percent available from Table 4)
    pounds P per acre x 2.27 = pounds P2O5 per acre

Note
Do not perform the conversion from P to P2O5 if lab results are given in units of P2O5.

________ x 2.27 = ________ pounds P2O5 per acre

  1. Potassium available at calculated application rate for nitrogen.
    Lagoon
    inches x pounds K per acre-inch x percent available = pounds K per acre
    Slurry
    K-gal per acre x pounds K per K-gal x percent available = pounds K per acre
    Solid
    tons per acre x pounds K per ton x percent available = pounds K per acre
    (Percent available from Table 4)
    ________ x ________ x ________ = __________ pounds K per acre
    pounds K per acre x 1.2 = pounds K2O per acre

Note
Do not perform the conversion from K to K2O if lab results are given in units of K2O.

________ x 1.2 = pounds K2O per acre

Solid dairy manure worksheet

  1. Crop nutrient requirements (from soil test)
    Fescue
    Yield 3 tons per acre
    N 120 pounds per acre
    P2O5 75 pounds per acre
    K2O 140 pounds per acre
  2. Available ammonia nitrogen (NH4-N) nitrogen.
    pounds NH4-N per ton x percent available = pounds NH4-N per ton
    (percent from Table 1)
    5 pounds per ton x 0.2 percent available = 1.0 pounds per ton
  3. Nitrogen available from this year's organic fraction.
    (percent available first year from Table 2)
    5 pounds per ton x 0.5 percent available = 2.5 pounds per ton
  4. Residual nitrogen abailable from previous years' organic fraction.
    (From Table 4: One year ago, 21 tons of dairy waste were applied to the field, 19 tons were applied two years ago, and 22 tons were applied three years ago.)
    (Percent available from Table 2.)
    1 year ago: 21 tons x 4 pounds per ton x 0.10 = 8.4 pounds per acre
    2 years ago: 19 tons x 6 pounds per ton x 0.05 = 5.7 pounds per acre
    3 years ago: 22 tons x 4 pounds per ton x 0.05 = 4.4 pounds per acre
    Total = 18.5 pounds per acre
  5. Manure application rate to supply nitrogen.
    ____(crop N requirement) - (residual N) ____
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 18.5
    1.0 + 2.5
    = 29.0 tons per acre
  6. Phosphate available at calculated application rate for nitrogen.
    2O5 per ton x percent available = pounds P2O5 per acre
    (P2O5 per ton from Table 5 = 4; percent available from Table 3)
    29.0 tons per acre x 4 pounds per ton x 0.8 = 92.8 pounds per acre

Note
92.8 pounds per acre of P2O5 is applied versus 75 pounds per acre recommended by the soil test.

  1. Potash available at calculated application rate for nitrogen.
    2O per ton x percent available = pounds K2O per acre
    (K2O per ton from Table 4 = 11; percent available from Table 3)
    29 tons per acre x 11 pounds per ton x 1.0 = 319 pounds per acre

Note
319 pounds per acre of K2O is applied versus 140 pounds per acre recommended by the soil test.

Liquid dairy manure worksheet

  1. Crop nutrient requirements (from soil test)
    Fescue
    Yield 3 tons per acre
    N 120 pounds per acre
    P2O5 75 pounds per acre
    K2O 140 pounds per acre
  2. Available ammonia nitrogen (NH4-N) nitrogen.
    4-N per K-gal x percent available = pounds NH4-N per K-gal
    (percent from Table 1)
    10 pounds per K-gallon x 0.2 percent available = 2 pounds per K-gallon
  3. Nitrogen available from this year's organic fraction.
    (percent available first year from Table 2)
    20 pounds per K-gallon x 0.5 percent available = 10 pounds per K-gallon
  4. Residual nitrogen available from previous years' organic fraction.
    From Table 5: One year ago, 7,000 gallons of dairy waste were applied to the field, 6,000 gallons were applied two years ago, and 7,000 gallons were applied three years ago.
    (Percent available from Table 2.)
    1 year ago: 7 K-gallon x 16 pounds per K-gallon x 0.10 = 11.2 pounds
    2 years ago: 6 K-gallon x 23 pounds per K-gallon x 0.05 = 6.9 pounds
    3 years ago: 7 K-gallon x 14 pounds per K-gallon x 0.05 = 4.9 pounds
    Total = 23.0 pounds per acre
  5. Manure application rate to supply nitrogen.
    (crop N requirement) - (residual N) - ____
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 23
    2 + 10
    = 8.1 (K-gal per acre) = 8,100 gallons per acre
  6. Phosphate available at calculated application rate for nitrogen.
    2O5 per K-gal x percent available = pounds P2O5 per acre
    (P2O5 per K-gal from Table 5 = 14, percent available from Table 3)
    8.1 (K-gal per acre) x 14 pounds per K-gal x 0.8 = 90.7 pounds per acre

Note
90.7 pounds per acre of P2O5 is applied versus 75 pounds per acre recommended by the soil test.

  1. Potash available at calculated application rate for nitrogen.
    2O per K-gal x percent available = K2O per acre
    (K2O per K-gal from Table 5 = 28; percent available from Table 3)
    8.1 (K-gal per acre) x 28 pounds per K-gal x 1.0 = 226.8 pounds per acre

Note
226.8 pounds per acre of K2O is applied versus 140 pounds per acre recommended by the soil test.

Lagoon effluent worksheet

  1. Crop nutrient requirements (from soil test).
    Fescue
    Yield 3 tons per acre
    N 120 pounds per acre
    P2O5 75 pounds per acre
    K2O 140 pounds per acre
  2. Available ammonia nitrogen (NH4-N) nitrogen.
    4-N per acre-inch x percent available = pounds NH4-N per acre-inch
    (percent available from Table 1)
    52 pounds per acre-inch x 0.8 percent available = 41.6 pounds per acre-inch
  3. Nitrogen available from this year's organic fraction.
    (percent available first year from Table 2)
    26 pounds per acre-inch x 0.5 percent available = 13.0 pounds per acre-inch
  4. Residual nitrogen available from previous years' organic fraction.
    From Table 6: One year ago, 2.0 inches of dairy lagoon waste water were applied to the field, 2.5 inches were applied two years ago, and 3.1 inches were applied three years ago.

    (Percent available from Table 2)
    1 year ago: 2.0 inches x 22 pounds per acre-inch x 0.10 = 4.4 pounds per acre
    2 years ago: 2.5 inches x 25 pounds per acre-inch x 0.05 = 3.1 pounds per acre
    3 years ago: 3.1 inches x 25 pounds per acre-inch x 0.05 = 3.9 pounds per acre
    Total = 11.4 pounds per acre
  5. Manure application rate to supply nitrogen.
    ____(crop N requirement) - (residual N) - ____
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 11.4
    41.6 + 13.0
    = 2 inches
  6. Phosphate available at calculated application rate for nitrogen.
    2O5 per acre-inch x percent available = pounds P2O5 per acre
    (pounds P2O5 per acre-inch from Table 6 = 41, percent available from Table 3)
    2 inches x 41 pounds per acre-inch x 0.8 = 65.6 pounds per acre

Note
65.6 pounds per acre of P2O5 is applied versus 75 pounds per acre recommended by the soil test.

  1. Potash available at calculated application rate for nitrogen.
    Number of inches applied x pounds K2O per acre-inch x percent available = pounds K2O per acre
    (K2O per acre-inch from Table 6 = 130; percent available from Table 3)
    2 inches x 130 pounds per acre-inch x 1.0 = 260 pounds per acre

Note
260 pounds per acre of K2O is applied versus 140 pounds per acre recommended by the soil test.

WQ310, reviewed July 1995

WQ310 Spreading Dairy Waste With Lab Analysis and Soil Test | University of Missouri Extension

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