Assessment of Different Nutrient Management and Organic Farming Practices via Soil Quality Index Under Maize–Wheat Sequence in Acid Alfisol of North‐Western Himalayas

ABSTRACT To precisely comprehend the impacts and determine the most suitable nutrient management and organic farming practices for sustainable agro‐ecosystems, assessment of soil quality at surface and sub‐surface depth is crucial. This study aims to assess the soil quality in response to different farming practices under maize‐wheat sequences. At two soil depths (0–0.15 m; and 0.15–0.30 m), physical, chemical and biological indicators of soil quality were evaluated under eleven nutrient management practices, including 100% NPK (RDF); 100% NPK + FYM at 10 t ha −1 (RDFM); 100% NPK + lime (RDFL); Organic farming practices (OF)s; natural farming system practiced using products of Desi cow (NFS‐ DC ); natural farming system practiced using products of Crossbred cow (NFS‐ CC ); natural farming system practiced using products of Buffalo (NFS‐ BF ); OF+25%NPK; NFS‐ DC + 25%NPK; NFS‐ CC + 25%NPK; and NFS‐ BF + 25%NPK, which were arranged in a completely randomised‐block design. For the soil quality assessment, minimum data set (MDS) of quality indicators was chosen using principal component analysis, and soil quality index (SQI) was then determined using a weighted additive technique. Results revealed that maize and wheat grain equivalent yield, available nutrients (N, P and K) were recorded higher under RDFM, followed by RDFL. However, water holding capacity, bulk density, aggregate stability, saturated hydraulic conductivity, available S, organic carbon, microbial count, microbial biomass C and N, and enzymatic activities greatly improved under OF+ 25%NPK. Among NFS practices, NFS‐ DC outperformed NFS‐ CC and NFS‐ BF in all the studied parameters. Available N, S, K, organic carbon, microbial biomass C, mean weight diameter and bulk density were selected as MDS. At 0–0.15 m soil depth, soil quality index (SQI) was recorded highest under organic farming+25%NPK (0.99), followed by RDFM (0.98), while the lowest value of SQI was observed under RDF (0.88). NFS‐ DC witnessed 1.27% and 1.97% higher values of SQI over NFS‐ CC and NFS‐ BF , respectively. The SQI value decreased in the sub‐surface soil layer (0.15–0.30 m), however treatment‐wise trend remains the same. At surface soil (0–0.15 m soil depth), available N contributed the most (35.7%) to SQI, followed by OC (27.9%), MBC (26.9%), available K (2.34%), S (0.91%) and MWD (0.51%). This study advocates the addition of organic manures with small quantity of chemical fertilisers that is, organic farming practices +25%NPK for maintaining the soil health and quality which could sustain/enhance system' productivity in a long run.