Natural Resources Conservation Service

APPENDIX I. Nutrient Uptake And Removal

Nutrient (nitrogen, phosphorus, potassium) content values were established for each of the crops listed in the 1992 Census of Agriculture that were included in this study. With a very limited number of exceptions, all crops in the census database were included in this project if harvested acres and harvested yields were available. Vegetable, citrus, and nut crops were not included in the study.

For this project, a basic assumption was made that plant residues were not removed from the field unless they were routinely considered part of the harvested material. For example, the crop residue from corn harvested as grain was assumed to remain in the field. For corn harvested as silage, both the ears and stalks were considered to be removed from the field. Similar logic was used for all other crops included in this project.

A. LEGUME AND NON-LEGUME AGRONOMIC OR NON-GRAZED FORAGE PLANTS

Nutrient content values were established for each crop. These values are displayed in Table A-1. For agronomic and forage crops (including both legume and non-legume plants) harvested as hay, haylage, or silage, the assigned values were for each unit of yield. For example, nutrient values were established for a bushel of corn, for a ton of hay or silage, and for 100 pounds (cwt.) of birdsfoot trefoil seed. Nutrient content as a function of yield unit facilitated the calculation of total nutrient content for each crop on each farm.

The units of yield most frequently associated with the crop were used for this project, except for some seed crops where yield units were converted to 100 pounds (cwt.).

To establish nutrient content values for agronomic and forage crops, a literature search was done of published sources of plant nutrient composition. References cited are listed on page 9 of this appendix. The average value (dry matter basis) was calculated for each plant from among all individual values complied from among all references. This average value was adjusted to reflect the estimated nutrient content at the dry matter content at which the plant is harvested. This adjusted value was then used to establish plant nutrient content contained in each yield unit of harvested biomass.

An example of the computational process is illustrated below for nitrogen in field corn, using the following values:

The intermediate value in this equation establishes the plant nitrogen content in a bushel of corn at 100 percent dry matter. This value, when multiplied by "Percent Dry Matter", corrects the estimated plant nitrogen content to the quantity contained in a bushel of corn at 86.7 percent dry matter.

The same computational process was used to calculate plant nutrient content values for each of the other plants listed in Table A-1. The symbol "*" shown in the table indicates that no data were available for the plant or variable.

Table A-1 also lists the nitrogen, phosphorus, and potassium values used in this study. These values reflect the estimated quantities of nitrogen, phosphorus, and potassium (in pounds) per unit yield at the "Percent Dry Matter," which is the average calculated plan dry matter value obtained from the literature search and used to correct estimated plant nutrient content to the proper dry matter basis.

Columns showing "Plant Composition (dry matter basis)" list the average nitrogen, phosphorus, and potassium concentrations of these plants at 100 percent dry matter. These are the calculated averages obtained from the literature review.

In developing the nutrient application rates for this category of plants, nutrient utilization efficiency factors were established for each of the nutrients. For phosphorus and potassium an efficiency factor of 100 percent was used. This factor was based on the assumption that over time, one pound of phosphorus and potassium would be available for plant uptake for each pound applied in the manure. For nitrogen, a recovery factor of 70 percent was used - 1.43 pounds of nitrogen were applied for each 1.0 pounds of uptake and removal in harvested biomass.

The nitrogen recovery factor used for this study did not account for nitrogen losses that are a function of manure application technique. It is recognized that significantly lower nitrogen recovery factors would be appropriate when manure is not incorporated. since this study focuses on the fundamental relationship between manure nutrient content and plant nutrient utilization, nitrogen losses associated with manure application technique was not considered.

On farm nutrient balances were calculated by comparing on-farm nutrient utilization with on-farm nutrient availability from the recoverable manure from confined livestock on the farm.

County totals for nutrient removal were aggregated from data complied for individual farms. County nutrient balances were determined by comparing county totals for nutrient consumption with county total for nutrient production and availability from the recoverable manure of the confined livestock populations of the county.

For the farm and county level nutrient consumption aggregations, summaries were prepared for the following categories of land uses:

1. Non-Legume Cropland & Hayland
2. Non-Legume Cropland & Hayland + Pastureland
3. Non-Legume + Legume Cropland & Hayland + Pastureland
4. Non-Legume + Legume Cropland & Hayland + Pastureland + Non-grazed Woodland
5. Non-Legume + Legume Cropland & Hayland + Pastureland + Non-grazed Woodland + Rangeland

For additional information about the nutrient values used for agronomic and forage plants, or for information about the data for the analysis of the final two categories of land use described above, contact:

Charles H. Lander

Nutrient Management Specialist

Natural Resources Conservation Service

Post Office Box 2890, Room 6155-S

Washington, DC 20013

Email: charles.lander@usda.gov

REFERENCES FOR PLANT NUTRIENT CONTENT INFORMATION FOR LEGUME AND NON-LEGUME AGRONOMIC OR NON-GRAZED FORAGE PLANTS

Howard, F.D., MacGillivray, J.H., and Yamaguchi, M., Nutrient Composition of Fresh California Grown Vegetables, California Agricultural Experiment Station, Bulletin No. 788, California Department of Agriculture, September 1962.

Morrison, F.B., Feeds and Feeding, A Handbook for Student and Stockman, 1959.

U.S. Department of Agriculture, Human Nutrition Information Service, Consumer Nutrition Center, Composition of Foods, Fruits and Fruit Juices, Raw, Processed, Prepared, Agricultural Handbook No. 8-9, August 1982.

Fonnesbeck, P.V., Lloyd, H., Obray, R., and Romesburg, S., IFI Tables of Feed Conversion, International Feedstuffs Institute, Utah Agricultural Experimentation Station, November 1984

National Research Council, Board on Agriculture, Committee on Animal Nutrition, and Canada Department of Agriculture, Research Branch, Committee on Feed Composition, Atlas of Nutritional Data on United States and Canadian Feeds, (Washington, DC: National Academy of Sciences, 1971).

U.S. Department of Agriculture, Human Nutrition Information Service, Nutrition Monitoring Division, Composition of Foods, Nut, and Seed Products, Raw, Processed, Prepared, Agricultural Handbook No. 8-12 (Washington, DC: U.S. Department of Agriculture, 1984).

Ensminger, M.E., Oldfield, J.E., and Heinemann, W.W., Feeds and Nutrition, Second Edition.

B. PASTURE, CROPLAND USED FOR PASTURE, AND RANGELAND

For pasture, cropland used for pasture, and rangeland, nutrient values were established on a per acre basis. This was necessary since yield information was not available for land use categories. Nutrients from manure were applied at a rate considered adequate to supplement the nutrients supplied by direct defecation of the animals grazing such land.

For cropland used for pasture and true pasture, the assumption was made that 100 percent of the acreage reported in the census could be accessible for the application of manure. For rangeland, the assumption was made that only 40 percent of the acreage reported in the census would receive manure applications. This assumption was based on the premise that for much of the true rangeland, the composition and health of the plant community could be damaged by the application of manure.

Variables K788 and K796 in the agricultural census database identify land grazed by animals (this excludes grazed woodland which is not being considered in this study). The following rules should be used to allocate manure on land in these categories:

1. K788, Cropland used for Pasture

   a. 50 percent of the cropland used for pasture should receive the following nutrient application rates:

   Nitrogen	100 pounds per acre
   Phosphorus	40 pounds per acre
   Potassium	60 pounds per acre

   b. 50 percent of the cropland used for pasture should receive the following nutrient application rates:

   Nitrogen	50 Pounds per acre
   Phosphorus	20 pounds per acre
   Potassium	30 pounds per acre

   c. Use the same recovery factors identified under cropland when developing the balances between nutrient availability and nutrient uptake and removal.

2. K796, Other Pastureland and Rangeland

   Different rules apply to nutrient application on pastureland and rangeland. For true pastureland (as is common in the Eastern United States) the rules documented for cropland used for pasture apply. For true rangeland, the following nutrient application rates apply:

   a. 20 percent of the rangeland should receive the following nutrient application rates:

   Nitrogen	16 pounds per acre
   Phosphorous	7 pounds per acre
   Potassium	10 pounds per acre

   b. 20 percent of the rangeland should receive the following nutrient application rates:

   Nitrogen	32 pounds per acre
   Phosphorus	14 pounds per acre
   Potassium	20 pounds per acre

   Variable K796 in the census database includes pasture and rangeland. The data contained in Table A-2 was used to partition the total acreage reported in the census as "Other Pasture and Range" into the appropriate acreage of either pasture or rangeland. The nutrient application rules were then applied to these individual values.

3. When developing the nutrient balances, use the nutrient recovery factors previously discussed.

For additional information about the factors used to determine nutrient application rates on the grazed land included in this study contact:

Dennis Thompson

National Range Grazinglands Ecologist

Natural Resources Conservation Service

Post Office Box 2890, Room 6150-S

Washington, DC 20013

Email: dennis.thompson@usda.gov

* NOTE: Unlisted states are assumed to be 100 percent pasture.

C. NON-GRAZED PRIVATELY OWNED WOODLAND

Nutrient application rates on non-grazed woodland were again established on a per acre basis. For woodland, a general assumption was made that in any given area, only a percentage of the woodland acres was physically accessible for land application of manure. The value used for this study was 50 percent.

Census variable K795 identifies acres of non-grazed woodland. Woodland is a potential area on which manure can be spread to meet timber nutrient needs. The following rules should be used to allocate manure on woodland:

1. Per acre manure application rates should be based upon supplying the following quantities of nutrients:

   Nitrogen	100 pounds per acre
   Phosphorus	20 pounds per acre
   Potassium	60 pounds per acre

2. As with cropland, use a nitrogen recovery factor of 70 percent, or 1.43 pounds of nitrogen applied for each 1.0 pound of plant uptake and removal.
3. Assume that approximately 50 percent of the reported woodland acres is accessible to equipment that would be used to apply manure.
4. Apply the above rules only to privately owned, non-federal, non-grazed woodland acres.

For additional information about the factors used to determine nutrient application rates on woodland in this study contact:

Keith Tichnor

National Forester

Natural Resources Conservation Service

Post Office Box 2890, Room 6169-S

Washington, DC 20013

Email: keith.tichnor@usda.gov

II. MANURE CHARACTERISTICS

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