Impact of Long-Term Nutrient Supply Options on Soil Aggregate Stability after Nineteen Years of Rice–Wheat Cropping System

Abstract

Continuing soil degradation remains a serious threat to future food security. Soil aggregation can help protect soil organic matter from biodegradation; it affects soil physical (aeration), chemical (water infiltration), and biological (microbial) activities. The integrated plant nutrition system (IPNS) and organic farming (OF) options have been contemplated as a sustainable strategy to sustain soil aggregate stability under adverse climatic conditions and a possible tool to restore degraded soil systems. Results suggested that the application of plant nutrients based on IPNS and soil test crop response (STCR) including mineral fertilizers and organic manure (farmyard manure: FYM) improved soil aggregate stability and mean weight diameter (MWD) under rice–wheat cropping systems. A long-term (19 year) cropping system (rice–wheat) experiment was examined to identify best nutrient management practices. Seven nutrient supply options were applied: organic, mineral fertilizer in combination with IPNS, IPNS + B/IPNS + C to improve soil aggregate stability and MWD after completing 19 cropping cycles of rice–wheat cropping systems. Results showed that significantly higher (+31%) macroaggregates were dominant in the surface soil layer than in the subsurface soil. The significantly highest macroaggregates were observed under OF (60.12 g 100 g−1 dry soil) management practices followed by IPNS options. The MWD was significantly increased (+17%) between surface and subsurface soil. Maximum MWD was reported with OF (0.93 mm) management practices followed by the IPNS + C (0.78 mm), IPNS + B (0.77 mm), IPNS (0.70 mm), STCR (0.69 mm), NPK (0.67 mm), and unfertilized control (0.66 mm) plots. Overall, results suggest that the adoption of IPNS options, such as organic farming (OF), RDF, STCR, and inclusion of pulses (berseem and cowpea), significantly improved all soil aggregation fractions in the soil system and also offered an additional benefit in terms of soil sustainability.