Impact assessment of integrated walnut fruit sequencing in exposed subsoil on vegetative growth traits, soil quality indicators and biological diversity in rainfed ecological system

This study monitored the impacts of integrated fruit-based cropping systems on vegetative growth traits, nutrient acquisition, microbial biomass and diversity in rhizosphere soil. Twelve cropping systems (CS) comprising Walnut-Peach-Sunhemp-Chrysanthemum (WPSC), Walnut-Peach-Sunhemp-Tomato-Marigold (WPSTM), Walnut- Nectarines-Sunhemp-Chrysanthemum (WNSC), Walnut-Nectarines-Sunhemp-Tomato-Marigold (WNSTM), Walnut- Plum- Sunhemp-Chrysanthemum (WP-SC), Walnut-Plum-Sunhemp-Tomato-Marigold (WP-STM), Walnut-Nectarines- Sunhemp-Chrysanthemum-Tomato-Marigold (WNSCTM), Walnut-Apple-Sunhemp-Tomato-Marigold (WASTM), Walnut-Nectarines-Sunhemp-Soybean-Marigold (WNSSM), Walnut-Nectarines-Sunhemp-Cucumber-Marigold (WNSCuM), Walnut-Nectarines-Sunhemp-Cauliflower-Marigold (WNSCauM) and Walnut-Nectarines (WN) have been demonstrated. The intercrop sequencing significantly improved vegetative growth and soil fertility indicators of exposed subsoils. Maximum moisture retention (25.2%), WHC (17.6%) and SOC (7.36 g/kg) was recorded in WNSCTM. Available N, P, K, exchangeable Ca, Mg were improved by 30.1%, 34.3%, 20.5%, 92.1%, 78.3%, respectively, over walnut-nectarines. DTPA–extractable micronutrient cations (Fe, Cu, Zn, Mn) improved by 64.8%, 58%, 44.5%, 85.7%, respectively. Microbial biomass-C (MBC), microbial biomass-N (MBN), and the cultivable plate counts of Bacillus species, Pseudomonas species, soil fungi, Azotobacter chroococcum and actinobacteria exhibited significant variability. On an average, significantly higher cultivable microbial diversity was observed. Microbial communities of Pseudomonas (132.2%), Bacillus (141.4%), soil fungi (241.3%), A. chroococcum (222.1%) and actinobacteria (206.9%) improved significantly. Correlation analysis resulted in significant association (P<0.05). Principal component analysis (PCA) accounted for 96.1% of the total variance within CS. PCA also identified MBC, MBN, and the microbial communities as major drivers for the variability among CS. It can be inferred that integrated fruit based sequencing is a better option for improving agronomic performance in terms of nutrient supply, recycling and microbial biomass capacity to generate eco-friendly soil quality management for sustainability in rural farming ecosystem.