Change in soil fertility as influenced by varying levels of fertilization to Kharif crops and different wheat based cropping systems in southern Rajasthan

A field experiment was conducted on sandy clay loam soil during kharif and rabi of 2008–09 and 2009–10. There were 3 wheat -based cropping systems (maize -wheat, groundnut -wheat and clusterbean –wheat) and 3 treatments (100% NPK, 100% NPKS and 100% NPKSZn) applied to kharif crops, in the main plots and 3 fertilizer (75, 100 and 125% NPK to wheat) in the sub-plots, was laid out in split plot design with 3 replications. Groundnut – wheat cropping system as well as 100% NPKSZn to kharif crops significantly higher wheat-grain equivalent yield (7118 kg/ha) and (7019 kg/ha) and available N, P and K of soil. Successive increase in fertility levels up to 125% NPK significantly increased wheat – grain equivalent yield (7063 kg/ha) and available N, P, K and Zn while available S decreased significantly with successive increase in fertility levels up to 125% NPK. Balance sheet of nutrients indicated maximum deficit of nitrogen (−108.48 kg/ha) and sulphur (−37.06 kg/ha) in groundnut – wheat cropping system and potassium deficit (−164.33 kg/ha) in maize – wheat cropping system. Maximum deficits of N (−58.28 kg/ha) and K (−177.50 kg/ha) and positive zinc balance (+ 11.281 kg/ha) were recorded under 100% NPKSZn. Application of 125% NPK to wheat recorded maximum positive balance of N (+ 17.02 kg/ha) and P (+ 122.76 kg/ha) but maximum deficits of K (−153.23 kg/ha) and S (−32.63 kg/ha), Maximum zinc balance (+ 3.462 kg/ha) was observed under 75% NPK. Groundnut – wheat cropping system recorded maximum positive balances of available N (+ 30.08 kg/ha) and P (+ 4.08 kg/ha).