Ohio State University Extension

Ohio State University Extension
Department of Horticulture and Crop Science
2021 Coffey Road, Columbus, Ohio 43210-1044

Best Management Practices: Land Application of Animal Manure


Land application of animal manure is an efficient utilization alternative because of usually lower costs compared to treatment and the nutrient benefits derived by crops from the manure. Manure nutrients help build and maintain soil fertility. Manure can also improve soil tilth, increase water-holding capacity, lessen wind and water erosion, improve aeration, and promote beneficial organisms. There are two principal objectives in applying animal manure to land: 1) ensuring maximum utilization of the manure nutrients by crops and 2) minimizing water pollution hazard.

Surface spreading and subsurface injection are two of the most common land-application methods. Several guidelines should be followed to achieve maximum nutrient use with minimal environmental hazard:

Available land for manure application is an important consideration for existing livestock operations as well as new or expanding operations. Typically, if enough land is available in an operation to produce feedstuffs for the animals, there is enough land to apply manure nutrients to minimize environmental effects.

When planning a new operation or expanding an existing operation, enough land area for manure application must be included in the plan. A conservative approach to determining the amount of land required is to consider the crop nutrient removal of the harvested crop. This will ensure that enough land area is available in future years to prevent nutrient buildup in the soil beyond suggested agronomic and environmental levels. For information on determining required land area for manure application based on crop nutrient removal, refer to "Land Required for Manure Application Based on Crop Removal."

Land application of plant nutrients, including manure, must take into account both crop needs and the potential for environmental degradation. Nutrients should not be applied in quantities that exceed the amount needed for adequate plant nutrition. All nutrient sources from commercial fertilizer, manure, and sludge application must be considered. Excess application may induce nutrient deficiencies in the soil and increase the potential for excess nutrients to enter waterways. High nutrient concentrations can accelerate eutrophication, a condition that reduces dissolved oxygen in the water, increasing plant growth and limiting animal life.

Manure contains plant nutrients and should be managed as a mixed fertilizer applied to satisfy crop nutrient needs. Alternate strategies are available to animal producers who have more manure than can be effectively land applied based on nutrient needs. In many situations, relatively deep incorporation and intensive control of runoff at the application site can minimize environmental impacts.

In animal manure management, phosphorus (P) is the nutrient of major concern on soils with high phosphorus fertility levels. Phosphorus applied to fields as manure or commercial fertilizer can move into bodies of water during erosion and runoff events, and is largely responsible for the accelerated eutrophication of many bodies of water in Ohio. It accumulates in soils if applied in quantities greater than those removed by crops. Accumulation of phosphorus in the soil can be measured by accepted soil test procedures. Agronomic crops grown in Ohio rarely respond to applications of additional phosphorus when soil test levels exceed 30 ppm (60 lb/A) of phosphorus, and crops grown in soils with very high phosphorus levels may actually produce lower yields due to nutrient imbalances. Concentrations of algal-available phosphorus (the phosphorus responsible for eutrophication) increase as soil-test phosphorus levels increase, meaning that as soil concentrations of phosphorus rise, the potential increases for soils to degrade the environment through runoff and erosion. Slowing the eutrophication of Ohio's surface waters involves reducing the amount of phosphorus delivered to these waters. Therefore, recommended strategies for manure applications to land are based on the following principles:

Factors Controlling Application Rate

The factors that most often limit the amount of manure that should be applied to cropland are existing soil-fertility levels, manure nutrient content, crop nutrient needs, site limitations, slope, runoff potential, and leaching potential. Nitrogen and/or phosphorus is usually the limiting nutrient for manure application. All manure contains measurable amounts of both. Applying levels that exceed crop nutrient requirements may lead to nutrients entering surface waters or leaching into ground water.

The amount of nutrients available in raw manure varies with the type and size of animal. Table 1 provide average nutrient values. The nutrient composition of waste is affected by housing and the waste-handling system. Bedding and additional water can dilute manure, resulting in less nutrient value per pound. Nutrient losses from storage and handling reduce the amount of nutrient available for land application. Phosphorus and potassium losses are usually negligible, but nitrogen losses can be significant. Table 2 provides a comparison of nitrogen losses due to storage and handling. Land application methods also affect the amount of nutrients available for crop uptake. Most losses occur within 24 hours of application. Manure should be incorporated into the soil as soon as possible after application. Injecting, chiseling, or knifing liquid manure into the soil minimizes odors and nutrient losses to the air or as surface runoff. Tables 3 and 4 present approximate nutrient values for land-applied solid and liquid manure, taking into account handling and storage losses. The amount of nitrogen available in the soil depends on the method of application and days to incorporation. Table 5 can be used to estimate the availability of ammonia and organic nitrogen in the soil. The phosphorus and potassium applied to the soil will be available unless removed by surface runoff and soil erosion. Nearly 100 percent of total phosphorus and potassium from manure application are considered available the first growing season.

TABLE 1. Annual Raw Manure Production per 1,000 lb Animal Weight.

Animal Type Manure Tons/yr Prod Gal/yr Percent Solids Nutrient Content
N P2O5 K2O N P2O5 K2O
(lb/ton) (lb/1,000 gal)
Dairy 15.0 3614 12.7 10.0 4.1 7.9 41.5 17.0 32.8
Beef 11.0 2738 11.6 11.3 8.4 9.5 45.4 33.7 38.2
Veal 11.5 2738 8.4 8.7 2.1 9.0 36.5 8.8 37.8
Growing pig 11.9 3008 9.2 13.8 10.8 10.8 54.6 42.7 42.7
Mature hog 5.9 1425 9.2 13.9 10.8 10.8 57.5 44.7 44.7
Sow & litter 15.9 3894 9.2 14.2 10.7 11.1 58.0 43.7 45.3
Sheep 7.3 1679 25.0 22.5 7.6 19.5 97.8 33.0 83.5
Goat 7.0 1789 31.7 22.0 5.4 15.1 86.1 21.1 59.1
Layers 9.7 2464 25.0 27.3 23.5 13.2 107.5 92.5 52.0
Broilers 13.1 3285 25.0 33.4 16.7 12.5 133.2 66.6 49.8
Turkey 8.4 2044 25.0 23.7 20.8 16.9 97.4 85.5 69.5
Horse 8.2 2048 21.0 12.1 4.6 9.0 48.4 18.4 36.0

TABLE 2. Nitrogen Losses During Storage and Handling (a)

System % Nitrogen Lost
Dairy scrape and haul 15-35
Manure pack 20-40
Open lot 40-60
Deep pit (poultry) 15-35
Below-ground storage tank 15-30
Above-ground storage tank 10-30
Earth storage 20-40
Anaerobic lagoon 70-80
(a) Typical losses due to storage and handling between excretion and land application. Values adjusted for dilution. These values are in addition to any losses that occur during land application.

TABLE 3. Approximate Fertilizer Nutrient Values of Animal Manure at Time Applied to Land - Solid Handling Systems (a)

  Nutrient Content
Type of Livestock Bedding vs. No Bedding Dry matter Total N(b) NH4(c) P2O5(d) K2O(e)
(%) (lb/ton)
Swine Without bedding 18 10 6 9 8
With bedding 18 8 5 7 7
Beef cattle Without bedding (f) 52 21 7 14 23
With bedding 50 21 8 18 26
Dairy cattle Without bedding 18 9 4 4 10
With bedding 21 9 5 4 10
Sheep Without bedding 28 18 5 11 26
With bedding 28 14 5 9 25
Poultry Without litter 45 33 26 48 34
With litter 75 56 36 45 34
Deep pit (compost) 76 68 44 64 45
Turkey Without litter 22 27 17 20 17
With litter 29 20 13 16 13
Horses With bedding 46 14 4 4 14
(a) Manure spreader capacity: 1 bu = 40-60 lb.
(b) Ammonium N plus organic N, which is slow releasing.
(c) Ammonium N, which is available to the plant during the growing season.
(d) To convert to elemental P, multiply by 0.44.
(e) To convert to elemental K, multiply by 0.83.
(f) Open dirt lot.

TABLE 4. Approximate Fertilizer Nutrient Value of Animal Manure at Time Applied to Land - Liquid Handling Systems (a)

  Nutrient Content
Type of Livestock Bedding vs. No Bedding Dry matter Total N(b) NH4(c) P2O5(d) K2O(e)
(%) (lb/ton)
Swine Liquid pit 4 36 26 27 22
Lagoon (f) 1 4 3 2 4
Beef Liquid pit 11 40 24 27 34
cattle Lagoonf 1 4 2 9 5
Dairy Liquid pit 8 24 12 18 29
cattle Lagoonf 1 4 2.5 4 5
Veal calf Liquid pit 3 24 19 25 51
Poultry Liquid pit 13 80 64 36 96
(a) Application conversion factors:
1,000 gal = about 4 tons; 27,154 gal = 1 acre-inch
(b) Ammonium N plus organic N, which is slow releasing.
(c) Ammonium N, which is available to the plant during the growing season.
(d) To convert to elemental P, multiply by 0.44
(e) To convert to elemental K, multiply by 0.83.
(f) Includes feedlot runoff water and is sized as follows:
single cell lagoon - 2 cu ft/lb animal weight;
two-cell lagoon - cell 1, 1-2 cu ft/lb animal weight
and cell 2, 1 cu ft/lb animal weight.

TABLE 5. Method of Calculating N Availability of Manures (a)

Available Nitrogen % Time of Application Days Until Incorporated (b)
(NH4) (Org.) (Date) (Days)
50 33 Nov-Feb <5
25 33 Nov-Feb >5
50 33 Mar-Apr <3
25 33 Mar-Apr >3
75 33 May-Jun <1
25 33 May-Jun >1
75 15 Jul-Aug <1
25 15 Jul-Aug >1
25 33 Sep-Oct <1
15 33 Sep-Oct >1
(a) The calculations are for all animal manures. It is assumed that 50% of the organic N in poultry manure is converted to NH4 rapidly and therefore is included in the NH4 column for calculating available N
(b) Incorporation is the mixing of manure and soil in the tillage layer. Disking is usually enough tillage for conserving N availability.

Only about one-third of the organic nitrogen in animal manure is available to crops during the year it is applied, and the remaining two-thirds, residual organic nitrogen, becomes part of the soil organic matter. It is mineralized or becomes available at the rate of about 5 percent a year. To determine how much nitrogen will be available to crops from manure applications, growers must take into account the mineralized nitrogen that will become available from previous manure applications (Table 6). Manure is also a good source of phosphorus and potassium. Tables 1, 3, or 4 can be used to calculate the amount of phosphorus and potassium that will be available from the manure. The phosphorus and potassium in manure will be as available to the crop during the year it is applied as would the equivalent amount of fertilizer-grade phosphorus and potassium.

TABLE 6. Percent of Residual Organic Nitrogen Made Available From Manure Applied Previous Years.

Years After Application Percent of Residual N Available
1 5.0
2 4.7
3 4.5
4 4.3
5 4.1
6 3.9
7 3.7
8 3.6
9 3.4
10 3.2

If the growers have applied phosphorus and potassium over the years, soil-test levels may be in the adequate to high range. To ensure high nutrient efficiency from added manure, growers should apply manure at rates that would satisfy only the crop's phosphorus and/or potassium needs. Use the method presented in "Determining Recommended Manure-Application Rates" when calculating application rates for phosphorus and potassium. It is important to note that manure contains much more potassium than magnesium or calcium, and after many years of continued manure application, the ratio of potassium to magnesium and calcium may be too high for optimum crop growth. To adjust the ratio, additional magnesium and/or calcium may have to be added as dolomitic or calcitic limestone. The soil should be tested regularly to determine these nutrient levels. If a mineral imbalance is suspected, plant-tissue analysis should be made to determine the extent of the problem.

TABLE 7. Recommended Maximum Manure Application Rates at Different Soil Test Levels (1).

Bray P Level
ppm (lb/A)
Surface Applied on High Runoff Potential Sites (2) Incorporated or Low Runoff Potential Sites (3)
N needs of non-legume crops N removal rate of legume crops N needs of non-legume crops N removal rate of legume crops
30-1254 (60-250) N needs or P removal rate for non-legume crops, whichever is less N or P removal rate for legume crops, whichever is less N needs of non-legume crops N removal rate for legume crops
125-1504 (250-300) Manure application for crop production purposes not recommended N needs or P removal rate for non-legume crops, whichever is less N or P removal rate for legume crops, whichever is less
>1504 (300) Manure application for crop production purposes not recommended Application of manure crop production purposes not recommended. If application is necessary, apply no more manure than supplies N or P removal for the next crop, whichever is less. A site plan which controls erosion and runoff is recommended.
(1) Applications of manure, at rates above these recommendations may require approval and/or permits by appropriate government agencies.
(2) Surface Application is any application at a depth which would be disturbed by tillage within the next three years. High runoff potential refers to sites where surface movements of manure and/or phosphorus are likely to occur from the field of application.
(3) Incorporation is any application at a depth which would NOT be disturbed by tillage within the next three years. Low runoff potential refers to sites where surface movement of manure and/or phosphorus from the field of application is not likely to occur under normal weather conditions.
(4) Yearly plant tissue and soil analysis recommended.

Fields receiving manure should be tested for available nutrients before application. The manure should also be tested. Application rates should be determined using the results of these tests. Table 7 provides recommended maximum manure application rates for different soil test levels and site conditions.

Adding high levels of manure may increase salts in soils and reduce plant stands. When manure is applied to a field, annual soil tests are strongly recommended to more accurately monitor soil nutrient levels and determine appropriate manure application rates.

Manure applications should not provide more available nitrogen (N) than what is needed by the succeeding crop. The determination of total available nitrogen should include credits for any contributions of the present or preceding crop, any nitrogen fertilizer added, and available nitrogen provided by previous manure applications.

Injection or incorporation by primary tillage promptly following application should minimize the potential for direct runoff. Manure should not be applied to the surface of wet, sloping, or frozen fields if normally anticipated rainfall would cause overland flow from the point of application. Liquid manure should not be applied at rates that exceed the volume needed to bring the soil to field moisture capacity and cause surface runoff or direct entry of manure into subsurface drainage system.

The manure utilization and cropping systems used on a particular field should maintain Bray P1 soil test phosphorus levels no greater than 30 ppm (60 lb/A) of phosphorus in the top 8 inches of soil. Special precautions should be taken if manure is applied where Bray P1 levels already exceed this level.

If manure must be applied to fields with levels greater than 30 ppm (60 lb/A) of phosphorus, note the following recommendations:

Factors Affecting Runoff Potential

Runoff potential is affected by numerous factors, some of which are fixed by the nature and location of the field and others that can be altered through management. Quantitative evaluation of these factors can be difficult because the factors either have not been quantified or they interact with each other in field conditions. Therefore, runoff potential must be determined on a site-by-site basis.

Naturally occurring factors that affect runoff potential include:

Management factors that can alter the potential for manure runoff into a stream include:

Prepared by:
Dr. Jay Johnson
Extension Agronomist
Dr. Don Eckert
Professor, Natural Resources

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.

TDD No. 800-589-8292 (Ohio only) or 614-292-6181

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