Comparative assessment of perennial grasses for restoring degraded semi-arid agroecosystems under contrasting moisture regimes

Although perennial grasses are increasingly recognized for restoring degraded lands, their restoration potential under contrasting moisture regimes in semi-arid agroecosystems remains poorly understood. Identifying grass species that can simultaneously enhance productivity, soil carbon (C) buildup, and ecosystem functioning is therefore critical for sustainable land restoration. This study evaluated the long-term effects of four perennial grasses-Guinea grass (GG), Tri-specific hybrid (TSH), Bajra napier hybrid (BNH), and Cenchrus ciliaris (CC) under rainfed and irrigated conditions on fodder productivity, soil fertility, soil organic carbon (SOC) fractions, carbon management index (CMI), and restoration efficiency index (REI). Irrigation significantly increased fodder productivity (GFY: ~12–45%; DFY: ~6–34%), total organic carbon (TOC, ~ 5%), SOC fractions [hot water soluble carbon (HWSC, ~ 19%), particulate organic carbon (POC, ~ 12%), and labile carbon (LC, ~ 6%)], soil microbial biomass carbon (SMBC,~23%), nutrient availability, and C buildup (~ 33%) compared with rainfed conditions. Among the grasses, GG consistently recorded the highest TOC (9.56 g kg− 1), SOC fractions, CMI (~ 187), and REI (> 80%), followed by TSH, indicating higher restoration potential. Correlation and network analyses identified CMI, LC, POC, microbial quotient, and SMBC Correlation and network analyses identified CMI, LC, POC, microbial quotient, and SMBC as strongly associated with soil quality improvement and ecosystem restoration. Therefore, GG and TSH are recommended for restoring degraded semi-arid lands due to their consistently higher CMI and REI. TSH is more suitable for rainfed conditions as it showed a comparatively smaller reduction in yield, whereas GG is preferable for maximizing biomass production and SOC restoration across moisture regimes; however, long-term studies are needed to evaluate the persistence of these benefits under future climate variability. Guinea grass and tri-specific hybrid showed the highest soil restoration potential. Irrigation enhanced fodder yield, nutrient availability, SOC fractions, and C buildup. CMI, LC, POC, and SMBC strongly linked to ecosystem restoration. TSH suits rainfed systems, while Guinea grass maximizes biomass and SOC gains.