Contribution of livestock excreta to nutrient balances

摘要: Livestock excreta make an important contribution to soil nutrient inputs and in many developing countries are the only significant input. However, there is little quantitative information available on excreta, manure production, application this makes it difficult obtain meaningful balances. A model has therefore been developed calculate produced recovered at national levels. Excretion rate coefficients for six farm animal categories using numbers weights obtained from FAO Internet database, production calculated 195 World 1996. In addition, time series results period 1961 1996 presented Kenya The Netherlands, representing contrasting agricultural systems, World. Total livestock were estimated contain 94 million tonnes of N, 21 P, 67 K. Cattle largest contributors with 60% total; pigs poultry account 10% 9%. Nutrients as 34 8.8 22.9 Recovery cattle about 30%, but poultry, which usually housed, recovery nearly 80%. As a percentage total inputs, accounts 14%, P 25%, K 20%. made by relative fertilizers plus declining. Since 1961, percentages have decreased; N 60 25, 50 38, 75 57. For most countries, will decrease further fertilizer use increases, some such Netherlands Japan, large industries, expected increase demand fall. remain main manure, discussed.