Changes in the nutrient status of soil caused by cropping and fertilization in a Typic Ustochrept

Field experiments were conducted during 1984-1986 on an alluvial (Typic Ustochrept) soil (pH 8.0. organic carbon 0.46%) at IARI farm. New Delhi to study the changes in available soil nutrients (N, P, K, Mn, Fe. Zn and Cu) at different production levels. Fertilizer was applied to wheat followed by maize, based on the Ta rge tted yield concept’, and mustard was grown after the sequence to estimate the residual effect of nutrients. Nutrient applications for the largest yield targets ( 6 t h a -1 of wheat followed by 4 or 5 t h a -1 of maize) resulted in a comparatively greater buildup of soil nutrients (N, P and K). the greatest yield of a succeeding mustard crop, and a better soil nutrient status than that at the start of the experiment, even after the mustard. When both crops were fertilized for the largest target yield with straight fertilizers (Urea. SSP and KC1), the additions of N, P and K and of micronutrient cations (Mn, Fe. Zn and Cu) maintained a favorable balance for major and trace nutrients and provided a sound basis for profitable crop productio