Nutrient management in wheat (Triticum aestivum)-based cropping systems in sub-humid southern zone of Rajasthan

A field experiment was conducted at Udaipur (Rajasthan) on sandy clay loam soil during the rainy (kharif) and winter (rabi) seasons of 2008–09 and 2009–10, to study the effect of nutrient management in wheat [Triticum aestivum (L.) emend. Fiori & Paol.]-based cropping systems in sub-humid southern zone of Rajasthan. Application of 100% NPKSZn significantly improved grain/pod/seed and stover/haulm/straw yields of maize (Zea mays L.), groundnut (Arachis hypogaea L.) and clusterbean [Cyamopsis tetragonoloba (L.) Taubert] over rest of the treatments. Growth attributes, viz. plant height, total tillers/m² and dry-matter accumulation; yield attributes, viz. effective tillers/m², grains/spike and 1,000-grain weight; grain (5.09 t/ha) and straw yields (7.61 t/ha) of wheat were significantly higher when it was grown after groundnut. Application of 100% NPKSZn to rainy-season crops significantly increased plant height, total tillers/m², dry-matter accumulation, effective tillers/m², grains/spike and 1,000-grain weight, grain yield (5.07 t/ha) and straw yield (7.61 t/ha) of wheat over 100% NPKS and 100% NPK. Successive increase in fertility levels up to 125% NPK applied to wheat significantly increased plant height, total tillers/m² and dry matter accumulation; yield attributes viz., effective tillers/m², grains/spike and 1,000-grain weight; grain (5.03 t/ha) and straw yields (7.55 t/ha) of wheat. Groundnut–wheat cropping system recorded significantly higher wheat– grain equivalent yield (7.12 t/ha) and net returns (84.2 × 10³ /ha) compared to other cropping systems. However, significantly higher benefit: cost ratio (3.66) was noted in clusterbean-wheat cropping system. Application of 100% NPKSZn to rainy-season crops significantly increased wheat–grain equivalent yield (7.02 t/ha), net returns (86.0 × 10³ /ha) and benefit: cost ratio (3.73) over other treatments. Successive increase in fertility levels up to 125% NPK significantly increased wheat–grain equivalent yield (7.06 t/ha), net returns (86.9 × 10³ /ha) and benefit: cost ratio (3.76) averaged over various wheat-based cropping systems. Maximum uptake of N, P, S and Zn were noted in groundnut–wheat cropping system, while maximum K uptake was in maize–wheat cropping system. Similarly, application of 100% NPKSZn to rainy-season crops and 125% NPK to wheat recorded the maximum uptake of N, P, K, S and Zn averaged over three wheat-based cropping systems. The highest available N and P status, lowest available S and Zn status, actual N and P gains, apparent positive P balance, actual losses of S and Zn and maximum negative N, K and S balances were observed in groundnut–wheat cropping system. However, the highest available K status and actual K gain were recorded in clusterbean-wheat cropping system. Zn balance by and large remained constant in all the cropping systems. Maximum actual gains in N, P, K, S and Zn and apparent negative balance of N, P and K were obtained with the application of 100% NPKSZn, while negative balance of S and Zn in 100% NPK and 100% NPKS, respectively. Application of 125% NPK to wheat recorded maximum actual gains in N, P, K and Zn, actual S loss and apparent negative balance of N, K and S while positive P and Zn balance in 75% NPK treatment.