Changes in Available Nitrogen, Phosphorus and Potassium in Soils of Different Fertility Status as Affected by Groundnut-Wheat Rotation

The changes in available N (alkaline KMnO₄ oxidisable), P (Olsen's extract able) and K (NH₄OAc extractable) in the surface (0–15 cm) and sub-surface (15–30 cm) layer of an arid-brown soil are reported. After 2 cycles of groundnut-wheat rotation, available N increased in both the layers and this built up was more in the surface layer and in soil having low initial fertility level. The available P and K status of both the layers declined with the cropping cycles and this reduction was more in soil with high fertility status. Growing a crop of groundnut resulted in increasing available nutrient status in the soil and wheat lowered it.