Limitations of guidelines governing rates of application of pig manure to land

• Published in: Agriculture and environment Vol. 4; no. 1; pp. 65 - 75
• Main Authors: Hilliard, E.P., Pearce, G.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.1978
• ISSN: 0304-1131
• DOI: 10.1016/0304-1131(78)90007-3

Analyses of pig diets and faeces from 24 commercial piggeries in Victoria showed a wide range in the concentration of N, P, K, Ca, Mg, Na, Fe, Zn, Cu, Cd, Pb and As. The composition of manure from each piggery was estimated as the difference between the dietary content of each element and available values for the retention of each element by an “average” pig. The variation in the estimated composition of the manures was considered in relation to those guidelines that recommend application rates of waste to land on the basis of a fixed parameter such as 500 kg N ha −1 yr −1 or 300 kg K ha −1 yr −1, or on the basis of land area per pig unit such as 55 pigs/ha. Because of the range in the estimated N content of pig manures, the quantities of manure supplying 500 kg N were calculated to range from 46 to 121 tonnes with an average of 63 tonnes; included in these quantities were widely varying amounts of other elements. The use of an index of land area per pig unit could result in excessive applications of N, as well as other elements. The potential environmental hazards of applying large amounts of minerals, including heavy metals, to land are discussed.