Nutrients Available from Livestock Manure - Footnotes

1 Sheep, goats, horses, and ponies were not included in this analysis as their manure is considered too difficult to recover.

2 Two additional scenarios were evaluated, but not reported herein: 1) non-legume and legume crop and hay production and pasture and non-grazed woodland, and 2) non-legume and legume crop and hay production and pasture and non-grazed woodland and rangeland. Estimates were also made for potassium, which are not reported herein. These additional results can be obtained from the authors.

3 The Agricultural Census is undertaken every 5 years. Since 1982, census years end in "2" and "7." Data collection begins in December of the census year and responses are due the following February 1. Reported data are for activities taking place during the census calendar year. The Census covers all operators of U.S. farms or ranches (Division A, SIC 01-02) that sold or normally would have sold $1,000 worth of agricultural products during the census year. The 1992 Census reflects the activities of some 1.9 million operators. Operators provide crop acreage and quantities harvested, inventories of livestock, value of products sold, land use and ownership, irrigation activities, amount of commodity credit loans, number of hired laborers, Federal program payments, and operator characteristics. However, underestimation of certain livestock populations in the Agricultural Census has been reported as a potential problem. Thus, the analyses undertaken and presented here may be recognized as conservative.

4 Tables in Section II of the Appendix identify 13 livestock groups by census inventory variable. Factors K806 (Heifers and Heifer Calves) and 807 (Steers, Calves, Bulls, and Bull Calves) were disaggregated for this analysis, resulting in the 16 livestock types referred to here. The rules developed and recovery factors used are described in Section III of the Appendix.

5 An animal unit (AU) is defined as 1,000 pounds of live weight of any given livestock species or any combination of livestock species. Animal unit equivalents are calculated for each livestock and poultry sector according to estimated rates of manure production for each species. Thus, AUs vary by sector-1 beef cow is equivalent to 1 AU, while 50 turkeys for breeding equal 1 AU. Table A-8 in the Appendix lists AU values for the livestock species evaluated in this analysis.

6 Since this "farm" is designed to show how the computations work for all livestock types, it has a surprising mix of livestock production types. Any similarity to actual farm situations is purely accidental.

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