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Land application of animal manure has been practiced for centuries. The practice was important because this manure was the primary source of fertilizer available. With increasing use of chemical fertilizer in more recent years, however, land application of manure has been regarded as a method of disposal of an unwanted waste product of intensive livestock operations. The present emphasis on recycling manure by land application as the most practical solution to ecological problems associated with this material, has again focused attention on its fertilizer value. The judicious use of manure may not only minimize risks to the environment but also benefit crop production by the addition of macro- and micro-nutrients and organic matter to the soil. To utilize a manure most effectively requires knowledge of the content of at least the principal nutrients, that is, nitrogen (N), phosphorus (P), and potassium (K). However, the NPK content of manure, and particularly a liquid manure, varies widely depending on many factors. A chemical analysis, therefore, is necessary to determine the level of these constituents. Problems of shipping samples to a testing laboratory, and possible delays before results are available, deter many farmers from making full use of these services. Some method of estimating the NPK content rather than relying either on guesswork or on published guidelines would be a logical alternative, but no such estimates appear to exist.
estimating plant nutrients in liquid manure from beef cattle
Aasen, A.K. and J.B. McQuitty 1974. ESTIMATING PLANT NUTRIENTS IN LIQUID MANURE FROM BEEF CATTLE. Canadian Agricultural Engineering 16(2):78-81.
78 - 81