Effect of Cropping Sequences and Nutrient Management Practices on Soil Quality under Rainfed Semiarid (Hot dry) Vertisol Soils of Western India

In order to study the effect of cropping sequences grown under different practices of nutrients management on soil quality, a long term experiment was conducted at research centre of All India Coordinated Research Project for Dryland Agriculture (AICRPDA), Targhadia, Rajkot falling under the jurisdiction of Junagadh Agricultural University. The experiment was conducted in a two-factor randomized block design (RBD) with three replications. The cropping sequences followed were: Sesamum-cotton, Sesamum-sesamum, Sesamum-groundnut, Bajra-groundnut, Bajra-bajra, Bajra-cotton, Castor-cotton, Castorcastor, Castor-groundnut, Cotton-groundnut, Cotton-cotton, Groundnut-groundnut. The nutrient management practices were: i) control without fertilizer, ii) recommended dose of fertilizer (RDF), iii) integrated nutrient management (INM) and iv) sole organic sources of nutrients. The results of the study indicated that the organic carbon was found to be medium (5.3 to 7.4 g kg⁻¹) across the cropping sequences. The application of sole organic sources resulted in highest available N (197.9 kg ha⁻¹) followed by INM treatments (182.3 kg ha⁻¹). Available P was found highest under cotton–groundnut cropping sequence (24.72 kg ha⁻¹). Cotton-cotton cropping sequence recorded significantly highest available K (449.1 kg ha⁻¹) and also available Zn, Fe, Cu, B to the extent of 1.06, 25.0, 3.36, 0.52 μg g⁻¹ respectively. Among the nutrient treatments, application of sole organic sources resulted in significantly highest amounts of available Zn, Fe, Mn and B. Significantly highest dehydrogenase activity was observed under sesamum-sesamum sequence, MBC under sesamum-cotton and labile carbon under castor-castor system. Application of sole organic sources of nutrients recorded significantly highest dehydrogenase activity (DHA), Microbial Biomass Carbon (MBC) and labile carbon followed by INM treatments. The relative order of performance of the cropping sequences in terms of relative soil quality indices (RSQI), when averaged over nutrient management treatments was as follows: Cotton-cotton (1.00) >Cotton-groundnut (0.93) > Castor-castor (0.88) > Bajra-groundnut (0.86) > Sesamum-sesamum (0.8) > Bajra-cotton (0.68) > Groundnut-groundnut (0.68) > Sesamum-groundnut (0.66) > Sesamum-cotton (0.64) > Castor-cotton (0.64) > Castor-groundnut (0.6) > Bajra-bajra (0.56). But when averaged over cropping sequences, the order of superiority of the treatments in terms of RSQI was: sole organic (1.00) > INM (0.72) > RDF (0.47). The results of the present study will be highly useful for improving the soil quality by using suitable combinations of crop sequences and nutrient management.