Bulletin 604
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. Tables 1 and 4 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 5 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 6 and 7 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 8 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 4. Annual Raw-Manure Production per 1,000-Pound Animal Weight
|
| Animal Type
| Manure Production
| Percent Solids
| Nutrient Content
|
| Tons/yr
| Gal/yr
| N
| P2O5
| K20
| N
| P2O5
| K20
|
| lb/ton
| lb/1,000 gal
|
| Dairy
| 15
| 3614
| 12.7
| 10.0
| 4.1
| 7.9
| 41.5
| 17.0
| 32.8
|
| Beef
| 11
| 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
|
| Swine
|
| 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
|
| Poultry
|
| 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 5. Nitrogen Losses During Storage and Handlinga
|
| System
| Nitrogen Lost %
|
| Solid
|
| Daily scrape and haul
| 15-35
|
| Manure pack
| 20-40
|
| Open lot
| 40-60
|
| Deep pit (poultry)
| 15-35
|
| Liquid
|
| 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 6. Approximate Fertilizer Nutrient Value at Time Applied to Land - Solid Handling Systemsa
|
| Type of Livestock
| Bedding vs. No Bedding
| Dry Matter %
| Nutrient Content
|
| Total Nb
| NH4c
| P2O5d
| K20e
|
| lb/ton
|
| Swine
| Without bedding
| 18
| 10
| 6
| 9
| 8
|
| With bedding
| 18
| 8
| 5
| 7
| 7
|
| Beef cattle
| Without beddingf
| 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 to 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 7. Approximate Fertilizer Nutrient Value at Time Applied to Land - Liquid Handling Systemsa
|
| Type of Livestock
| Manure Storage
| Dry Matter %
| Nutrient Content
|
| Total Nb
| NH4c
| P2OSd
| K20e
|
| lb/1,000 gal
|
| Swine
| Liquid pit
| 4
| 36
| 26
| 27
| 22
|
| Lagoonf
| 1
| 4
| 3
| 2
| 4
|
| Beef cattle
| Liquid pit
| 11
| 40
| 24
| 27
| 34
|
| Lagoonf
| 1
| 4
| 2
| 9
| 5
|
| Dairy cattle
| Liquid pit
| 8
| 24
| 12
| 18
| 29
|
| Lagoonf
| 1
| 4
| 2.5
| 4
| 5
|
| Veal calf
| Liquid pit
| 3
| 24
| 19
| 25
| 51
|
| Poultry
| Liquid pit 1
| 3
| 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 per 1 lb animal wt. Two-cell lagoon - cell 1, 1 to 2 cu ft per 1 lb animal wt; cell 2, 1 cu ft per 1 lb animal wt. |
| Table 8. Method of Calculating N Availability of Manuresa
|
| Available Nitrogen %
| Time of Application
| Days Until Incorporatedb
|
| NH4
| Organic
| Date
| Days
|
| 50
| 33
| Nov-Feb
| <5
|
| 25
| 33
| Nov-Feb
| >3
|
| 50
| 33
| Mar-Apr
| <3
|
| 25
| 33
| Mar-Apr
| >3
|
| 75
| 33
| Apr-Jun
| <1
|
| 25
| 33
| Apr-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 is therefore 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 9). Manure is also a good source of phosphorus and potassium. Tables 1, 4, 6, or 7 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 9. Percentage of Residual Organic Nitrogen Made Available From Manure Applied Previous Years
|
| Years After Application
| Percentage 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.
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 10 provides recommended maximum manure-application rates for different soil-test levels and site conditions.
| Table 10. Recommended Maximum Manure-Application Rates at Different Soil-Test Levelsa
|
| Bray P1 Level
| Surface Applied on High-Runoff-Potential Sitesb
| Incorporated or Low-Runoff-Potential Sitesc
|
| 0-60 lb P/A
| N needs of non-legume crops.
| N needs of non-legume crops.
|
| N removal rate of legume crops.
| N removal rate of legume crops.
|
| 60-250 lb P/Ad
| N needs or P removal rate for non-legume crops, whichever is less.
| N needs of non-legume crops.
|
| N or P removal rate for legume crops, whichever is less.
| N removal rate for legume crops.
|
| 250-300 lb P/Ad
| 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.
|
| >300 lb P/Ad
| Manure application for crop production purposes not recommended.
| Manure application for crop production purposes is 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 that controls erosion and runoff is recommended.
|
| a Application of manure at rates above these recommendations may require approval and/or permits by appropriate govemment agencies.
|
| b Surface application is any application at a depth that would be disturbed by tillage within the next three years. High-runoff potential refers to sites where surface movement of manure and/or phosphorus is likery to occur from the field of application.
|
| c Incorporation is any application incorporated at a depth that 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.
|
| d Yearly plant tissue and soil analysis recommended. |
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 systems.
The manure utilization and cropping systems used on a particular field should maintain Bray P1 soil-test phosphorus levels no greater than 60 pounds of phosphorus per acre in the top 8 inches of soil. Special precautions should be taken if manure is applied where Bray P, levels already exceed this level.
If manure must be applied to fields with levels greater than 60 pounds of phosphorus per acre, note the following recommendations:
- No additional phosphorus fertilizer should be used on such fields.
- Crops should be monitored for nutrient deficiencies using plant-tissue analysis. Increasing soil-test phosphorus and potassium levels above recommended levels increases the probability of yield-reducing nutrient imbalances.
- Manure should be applied in quantities such that the long-term phosphorus level at the soil surface does not increase appreciably. This can be accomplished by observing the following guidelines:
a. Ensure that applications supply no more nitrogen or phosphorus (whichever is lower) than will be removed by the next crop (one season) if the manure is surface- applied or incorporated to a shallow depth (within the tillage depth).
b. Incorporate manure below the depth of tillage, generally deeper than 8 inches, using rates great enough to satisfy nitrogen requirements for a succeeding grass crop. Note: Based on soil testing, shallow tillage may be necessary to reduce surface phosphorus levels that have increased due to crop- residue deposition. Producers should be aware that this system may promote development of a soil zone with extreme nutrient concentration that may increase phosphorus runoff if brought to the surface by subsequent tillage. Fields under such management should be sampled deep enough to include the zone of incorporation. On soils with high nutrient levels, manure application should be skipped for one or more seasons to allow depletion of accumulated nutrients.
- Adequate soil and water conservation should be practiced to control erosion and minimize runoff.
- Manure application is not recommended for crop production where the Bray P1 level in the top 8 inches of soil exceeds 300 pounds of phosphorus per acre.
- If deep application and incorporation of manure are required to maintain low runoff and more than 250 pounds of P2O5 per acre are applied, soil at the depth of application should not be brought to the surface for three years unless low-runoff conditions can be maintained. Moldboard plows should be set to two-thirds the depth of incorporation during this three-year period, and noninversion tillage tools such as chisel plows should be set no deeper than the depth of application. Deep incorporation of less than 250 pounds of P,O5 per acre may be conventionally tilled the following year.
