Fertility Studies on a Sandy Loam in Semi-Arid Tanzania

Abstract

N and P fertilizers applied to maize had considerable effects over a five-year period, especially when both were given. Initial applications of 47 lb/acre/P 2 O 6 with annual dressings of 58 lb N, produced a mean yield increase of 55 per cent above the control. K gave little response in the first three years, but thereafter became more important. ii2olb ammonium sulphate nitrate caused striking reductions in soil pH, Ca, Mg, K, total and organic P but increases in exch. Mn and soluble P. 112 lb double superphosphate increased the total and organic P and 651b K 2 O reduced organic P. Organic carbon suffered a mean loss of 33 per cent over five years. Recommendations are made regarding P 2 O 6 , N and K on this soil.