Impact of zero-till residue management and crop diversification with legumes on soil aggregation and carbon sequestration (original) (raw)

2019, Soil and Tillage Research

We evaluated the long-term impact of zero tillage (ZT) in post-rainy seasons (winter and summer) crop/s, crop residue management, and crop diversification on soil aggregation and carbon sequestration. The field experiment (started in 2009) was undertaken in split-plot design for seven consecutive years on a sandy loam soil of Kanpur, India. The experiment comprised of four tillage and crop residue management treatments: PTRconventional tillage (CT) without crop residue (PTR-CT), PTR-ZT without crop residue (PTR-ZT-R), PTR-CT with crop residue incorporation (PTR-CT+R), and PTR-ZT with surface crop residue retention (PTR-ZT + R) in main plot, and three cropping systems: rice-wheat (RW), rice-chickpea (RC), and rice-chickpea-mungbean (RCMb) in subplot. Treatment PTR-ZT + R resulted in 13% (p < 0.05) higher water stable macroaggregate over the PTR-CT. Meantime, PTR-ZT+R increased carbon content in macro-aggregate (28%) and meso-aggregate (39%) over the PTR-CT, because of added carbon through the surface-laden crop residue. The tillage and crop residue management followed the sequence of PTR-ZT+R > PTR-ZT-R > PTR-CT+R > PTR-CT (p < 0.05) across the soil depths for active and passive carbon pools. After seven years, PTR-ZT+R enhanced soil microbial biomass carbon (SMBC) and particulate organic carbon (POC) by 70 and 56% over PTR-CT, respectively. The RCMb and RC rotations increased (p < 0.05) the macro-and meso-aggregates, and aggregate mean weight diameter compared to the RW rotation in both soil depths. Crop rotations had the following trend: RCMb > RC > RW (p < 0.05) for SMBC and POC. Notably, treatment PTR-ZT+R with RCMb or RC rotations largely increased the carbon management index compared to the PTR-CT and RW systems. The structural indices and soil carbon parameters were significantly correlated to the rice grain yield, except microaggregated carbon. Thus, crop diversification with grain legume/s, zero tillage in post rainy season crop/s, and crop residue retention provided not only higher soil aggregation but also increased carbon sequestration in Inceptisol of subtropical humid climate.