Effects of Management on Soil Decomposers and Decomposition Processes in Grassland

Abstract

Decomposition processes in the worlds grasslands and croplands are considerably influenced by management. Factors such as fertilizer use, stocking and cutting intensity, choice of crops, cultivation practices and use of pesticides directly influence the nutrient supply for the decomposer community by affecting net primary production and how the resultant fixed chemical energy is utilized. Net primary production in grassland sites studied during the International Biological Programme ranged from 239 g/m² dry mass in semiarid areas to 4557 g/m2 in subhunid tropics with temperate grasslands falling in the range 702 to 3470 g/m² (Coupland 1979). The ranges reflect inherent differences in soil fertility and climate, but are also very much influenced by management. As much as 75% of plant production may be returned t the soil in extensively grazed, semiarid, natural grassland and as little as 3-5o may be assimilated by cattle (Coleman et al. 1976). At the other extreme, under conditions of intensive sheep grazing in temperate grasslands up to 60% of annual shoot production may be assimilated by the sheep (Hutchinson and King 1980a) while in intensively fertilized, mown grassland over 90% of shoot production may be harvested (Andrzejewska and Gyllenberg 1980).