Tillage and residue management effects on soil aggregation, organic carbon dynamics and yield attribute in rice –wheat cropping system under reclaimed sodic soil

Abstract

Conservation tillage and residue management are the options for enhancing soil organic carbon stabilization by improving soil aggregation in tropical soils. We studied the influence of different combinations of Village and residue management on carbnn stabilization in dirferent sized soil aggregates and also on crop yield after 5 years or continuous rice-wheat cropping system on a sandy loam reclaimed sodic soil or» th India. Compared to conventional tillage, water stable macroaggregates in conservation tillage (reduced and zero-Village) in wheat coupled with direct seeded rice (DSR) was increased by S0.13$ and water stable microaggregates of the later decreased by 10.IN in surrace soil. Residue incorporation caused a significant increment or i s.ssh in total water stable aggregates in surface soil (0—I 5 cm) and 7.53a* in sub-surface soil (I 5-30 cm). In surface soil, the maximum (I 9.2X) and minimum (8.9Z) proportion of total aggregated carbon was retained with >2 mm and 0.1-0.0S mm size reactions. respectively. DSR combined with zero Village in vVheat along with residue retention (Th) had the highest capability to hold the organic carbon in surface (11.57 g kg°' soil aggregates) with the highest stratification ratio of SOC (1.5). Moreover, it could show the highest cacbon preservation capacity (CPC) of coarse macro and mesoaggregates. A considerable proportion of the total SOC was found to be captured by the macroaggregates (>2-0.25 mm) under both surrace (67.1$) and sub-surface layers (S6.7$) leaving rest amount in microaggregates and ‘silt • clay' sized particles. From our study, it has been proved that DSR with zero tillage in wheat (with residue) treatment (T ) has the highest potential to secure sustainable yield increment (8.3$) and good soil health by improving soil aggregation (53.8$) and SOC sequestration (33.6$) with respect to the conventional tillage with transplanted rice (T, ) after five years or continuous rice—wheat cropping in sandy loam reclaimed sodic soil of hot semi-arid Indian sub- continent.