Residual soil health–productivity under integrated enriched compost and fertilizer management as a climate-resilient strategy to address agri-food security challenges in mustard

Soil degradation and increasing climate variability pose significant challenges to sustainable mustard production in semi-arid agroecosystems by impairing soil fertility, nutrient availability, and crop productivity. This study evaluated the residual effects of enriched compost and inorganic fertilizer integration on soil nutrient dynamics, biological indicators, nutrient uptake, and mustard productivity. A field experiment was conducted during 2021–2025, and the residual effects during the final crop season (2024–2025) were evaluated to assess the influence of enriched compost and inorganic fertilizer integration on soil nutrient dynamics, soil biological indicators, and mustard productivity, under semi-arid conditions. The treatments comprised absolute control (Ct), recommended fertilizer dose (RDF-100%; 80–40–40–40 kg N–P₂O₅–K₂O–S ha⁻¹), enriched compost at 6 Mg ha⁻¹ (EC-6), EC-6 + RDF-100%, and EC-6 + RDF-50%. The integrated treatment, EC-6 + RDF-100% maintained the highest residual soil fertility, recording available KMnO₄–N (172 kg ha⁻¹), Olsen–P (27 kg ha⁻¹), and NH₄OAc–K (239 kg ha⁻¹) concentrations than other treatments. Nitrogen mobilization efficiency index ranged from 5.8 to 6.9%, with the highest value under RDF-100%, whereas phosphorus mobilization efficiency was greatest (2.02%) under EC-6. Integrated nutrient management significantly enhanced soil organic carbon, dehydrogenase activity, microbial biomass carbon, nitrogen, and phosphorus relative to sole applications of compost or mineral fertilizers. Improved soil fertility and biological activity translated into superior crop performance. EC-6 + RDF-100% produced the highest seed yield (2.0 Mg ha⁻¹), stover yield (4.1 Mg ha⁻¹), and total biomass yield (6.1 Mg ha⁻¹), followed by EC-6 + RDF-50%. The same treatment also achieved the highest seed protein content (21.5%) and nutrient uptake, with seed nitrogen and phosphorus uptake reaching 70 and 13 kg ha⁻¹, respectively. These findings demonstrate that the residual effects of enriched compost integrated with inorganic fertilizers sustain nutrient availability, stimulate soil biological processes, enhance nutrient acquisition, and improve mustard productivity more effectively than sole compost or mineral fertilizer application. The residual effect of integrated application of EC-6 + RDF-100% emerges as a promising strategy for maintaining soil health and crop productivity in semi-arid agroecosystems.