University of Missouri Extension

WQ312, Reviewed January 2009

Spreading Dairy Waste Without Lab Analysis and With Soil Tests

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

General information

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, however, is to provide guidance for application of waste without the benefit of a lab analysis but with data from 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 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."

If a laboratory analysis is not available, average values of manure nutrients in similar waste management systems, as reported in the literature, must be used. Table 1 lists values for dairy waste.

Table 1
Average nutrient levels in dairy waste.1

Waste type Nitrogen P2O5 K2O
Total Organic Ammonia
Solid2 with bedding (pounds per ton) 9 4 5 4 10
Solid3 without bedding (pounds per ton) 9 5 4 4 10
Lagoon (pounds per acre-inch) 69 23 46 79 144
Liquid (slurry; pounds per acre-inch) 26 16 10 14 26

Notes
P2O5 = 2.27 x P.
K2O = 1.2 x K.

1 Actual values are highly dependent on dilution, bedding and other factors. Variations of 50 percent from average values are not uncommon.
321 percent dry matter. Source: MWPS18, Table 10-6).
318 percent dry matter. Source: MWPS18, Table 10-6).

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 2 shows the available ammonia nitrogen as a function of time until incorporation into the soil. Table 3 lists the percent of available organic nitrogen available with time. Table 4 gives the percent of various nutrients available in the growing season after application.

Table 2
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 3
Manure organic nitrogen available by year

Manure applied Percent organic-N available during current year
Current year 4 to 60
1 year ago 10
2 years ago 5
3 years ago 5

Table 4
Other minerals and micronutrients available in manure

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

This publication details a procedure for estimating the amount of manure to apply to meet the soil test recommendations for nitrogen, using a dairy manure of unknown nutrient analysis. The soil test may call for more than 100 pounds of nitrogen per acre to be added to satisfy crop needs, thus exceeding the 100 pounds per acre allowed under the "conservative management approach." However, one may wish to use this worksheet with 100 pounds of N per acre applied (conservative approach) to see what happens with P and K. A blank "Manure fertility worksheet" is included for actual applications.

Note
This approach cannot be used (to apply more than 100 pounds of N per acre per year) 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. No laboratory analysis of the manure to be applied is available. 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, 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?

Since no laboratory analysis of the manure is available, the average values from Table 1 will be used. 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

For the application of solid manure with no bedding, complete the "Solid dairy manure worksheet" below to determine the proper application rate. Assume the soil-plant filter area has not received manure from any source for the past three years. See Table 1 for average nutrients per unit of manure applied.

Liquid manure (slurry)

For the application of liquid manure (slurry) with no bedding, complete the "Liquid manure worksheet" below to determine the proper application rate. The soil-plant filter area received 3,800 gallons of liquid dairy manure per acre two years ago. See Table 1 for average nutrients per unit of manure applied.

Lagoon effluent

For the application of waste from a lagoon, complete the "Lagoon effluent worksheet" below to determine the proper application rate. The soil-plant filter area has received 1.45 inches of dairy lagoon effluent each of the past six years. See Table 1 for average nutrients per unit of manure applied.

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 per acre-inch x percent avail. = pounds NH4-N per acre-inch
    Slurry
    pounds NH4-N per K-gal x percent avail. = pounds NH4-N per K-gal
    Solid
    pounds NH4-N per ton x percent avail. = pounds NH4-N per ton
    (Percent available from Table 2)
    ________ x ________ = __________
    Note: K-gal = 1,000 gallons
  3. Nitrogen available from this year's organic fraction.
    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 3)
    ________ x ________ = __________
  4. 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 3)
    1 year ago: ________ x ________ x ________ = __________
    2 years ago: ________ x ________ x ________ = __________
    3 years ago: ________ x ________ x ________ = __________
    Total = __________
  5. Manure application rate.
    ______ (crop N requirement, line 1) - (residual N, line 4) ______
    (available NH4-N, line 2) + (available organic fraction, line 3)
    = application rate
    (____) - (____)
    (____) + (____)
    = ________
  6. 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)
    ________ x ________ x ________ = __________ pounds P per acre
    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).
    Crop Fescue
    Yield 3 tons per acre
    N, pounds per acre 120
    P2O5, pounds per acre 75
    K2O, pounds per acre 140
  2. Available ammonia (NH4-N) nitrogen.
    4-N per ton x percent available = pounds NH4-N per ton
    (Percent available in Table 2)
    4 pounds per ton x 0.2 available = 0.8 pounds per ton
  3. Nitrogen available from this year's organic fraction.
    pounds N per ton x percent available = pounds N per ton
    (Percent available first year from Table 3)
    5 pounds per ton x 0.5 available = 2.5 pounds per ton
  4. Since no manure was applied in any of the previous three years, no residual nitrogen is available.
  5. Manure application rate to supply nitrogen.
    ______(crop N requirement) - (residual N)______
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 0
    0.8 + 2.5
    = 36.4 tons per acre
  6. Phosphate available at calculated application rate for nitrogen.
    tons per acre x pounds P2O5 per ton x percent available = pounds P2O5 per acre
    (P2O5 per ton from Table 1 = 4; percent available from Table 4)
    36.4 tons per acre x 4 pounds per ton x 0.8 = 116.5 pounds per acre

Note
116.5 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.
    tons per acre x pounds K2O per ton x percent available = pounds K2O per acre
    (K2O per ton from Table 1 = 10; percent available from Table 4)
    36.4 tons per acre x 10 pounds per ton x 1.0 = 364 pounds per acre

Note
364 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, pounds per acre 120
    P2O5, pounds per acre 75
    K2O, pounds per acre 140
  2. Available ammonia (NH4-N) nitrogen.
    pounds NH4-N per K-gal x percent available = pounds NH4-N per K-gal
    (Percent available from Table 2)
    10 pounds per K-gal x 0.2 available = 2 pounds per K-gal

Note
K-gal = 1,000 gallons, e.g. 5 K-gal = 5,000 gallons

  1. Nitrogen available from this year's organic fraction.
    pounds N per K-gal x percent available = pounds N per K-gal
    (Percent available first year from Table 3)
    16 pounds per K-gal x 0.5 available = 8 pounds per K-gal
  2. Residual nitrogen available from previous years' organic fraction.
    Number of K-gal per acre x pounds N per K-gal x percent available = pounds N per acre
    (Percent available from Table 3)
    2 years ago: 3.8 K-gal x 16 pounds per K-gal x 0.05 = 3.0 pounds
  3. Manure application rate to supply nitrogen.
    ______(crop N requirement) - (residual N)______
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 3
    2 + 8
    = 36.4 tons per acre = 11.7 K-gal per acre = 11,700 gallons per acre
  4. Phosphate available at calculated application rate for nitrogen.
    Number of (K-gal per acre) x pounds P2O5 per K-gal x percent available = pounds P2O5 per acre
    (P2O5 per K-gal from Table 1 = 14; percent available from Table 4)
    11.7 (K-gal per acre) x 14 pounds per K-gal x 0.8 = 131.0 pounds per acre

Note
131.0 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 (K-gal per acre) x pounds K2O per K-gal x percent available = pounds K2O per acre
    (K2O per K-gal from Table 1 = 26; percent available from Table 4)
    11.7 (K-gal per acre) x 26 pounds per K-gal x 1.0 = 304.2 pounds per acre

Note
304.2 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).
    Crop Fescue
    Yield 3 tons per acre
    N, pounds per acre 120
    P2O5, pounds per acre 75
    K2O, pounds per acre 140
  2. Available ammonia (NH4-N) nitrogen.
    pounds NH4-N per acre-inch x percent available = pounds NH4-N per acre-inch
    (Percent available from Table 2)
    46 pounds per acre-inch x 0.8 available = 36.8 pounds per acre-inch
  3. Nitrogen available from this year's organic fraction.
    pounds N per acre-inch x percent available = pounds N per acre-inch
    (Percent available first year from Table 3)
    23 pounds per acre-inch x 0.5 available = 11.5 pounds per acre-inch
  4. Residual nitrogen available from previous years' organic fraction.
    inches x pounds N per acre-inch x percent available = pounds N per acre
    (Percent available from Table 3)
    1 year ago: 1.45 inches x 23 pounds per acre-inch x 0.10 = 3.3 pounds per acre
    2 years ago: 1.45 inches x 23 pounds per acre-inch x 0.05 = 1.7 pounds per acre
    3 years ago: 1.45 inches x 23 pounds per acre-inch x 0.05 = 1.7 pounds per acre
    Total = 6.7 pounds per acre
  5. Manure application rate to supply nitrogen.
    ______(crop N requirement) - (residual N)______
    (available NH4-N) + (available organic fraction)
    = application rate
    120 - 6.7
    36.8 + 11.5
    = 2.35 inches
  6. Phosphate available at calculated application rate for nitrogen.
    Number of inches applied x pounds P2O5 per acre-inch x percent available = pounds P2O5 per acre
    (P2O5 per acre-inch from Table 1 = 79, percent available from Table 4)
    2.35 inches x 79 pounds per acre-inch x 0.8 = 148.5 pounds per acre

Note
148.5 pounds per acre of P5 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 1 = 144; percent available from Table 4)
    2.35 inches x 144 pounds per acre-inch x 1.0 = 338.4 pounds per acre

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

WQ312, reviewed October 1993

WQ312 Spreading Dairy Waste Without Lab Analysis and With Soil Test | University of Missouri Extension

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