The Effect of Sewage Sludge and Chemical Fertilizer on Natural Pasture's Yield and Botanical Composition

Abstract

Meadows converted into poor quality pastureland, as a result of early and over grazing, must regained their productive capacity. Since sewage biosolid (sewage sludge) contains high ratio of organic matter and nutrients, its use as fertilizer has become widespread. The aim of this research is to investigate the usability of waste of sewage biosolid (SB) as fertilizer as an alternative to chemical fertilizers in amending the poor quality pastureland. In this study, in the first experiment 25, 50, 75 and 100 ton ha(-1) year closes of sewage biosolid (SB) and in the other one 50(N-1) +25(P-1), 100(N-2) +50(P-2), 150(N-3) +75(P-3), 200(N-4) +100(P-4) kg ha(-1) year doses of chemical fertilizers (CF) were applied to investigate their effects on yield and botanical composition. The experiment was conducted in complete block design with three replications in the same plots during two years. While the rate of contribution of grasses to the hay was increasing, rate of legumes was decreased by biosolid applications. In terms of biological diversity, the most stable botanical composition was reached by application of 25 ton ha(-1) year doses of biosolid and 50 kg N ha(-1)+25 kg P2O5 ha(-1) doses of chemical fertilizer. Green herbage, hay and crude protein yield and crude protein ratio were more increased by biosolid application. The highest yield was obtained from 75 ton ha(-1) year doses of biosolid and 150 kg N ha(-1) +75 kg P2O5 ha(-1) doses of chemical fertilizer. It was concluded that in similar ecological conditions, lowest doses of sewage sludge provided herbage with equal yield and high quality as the highest doses of chemical fertilizers.