Long term effects of tillage and residue management on soil aggregation, soil carbon sequestration and energy relations under rice–wheat cropping system in Typic Ustochrept soil of Uttar Pradesh

Abstract

A field experiment was conducted to investigate the influence of different combinations of tillage and residue management on carbon sequestration in different sized soil aggregates and also on crop yield after 4 years of continuous rice–wheat cropping system on Typic Ustochrept soil of Uttar Pradesh. Compared to conventional tillage, macro-aggregates in conservation tillage in wheat coupled with unpuddled transplanted rice (RT-TPR) was increased by 50.13% and micro-aggregates of the later decreased by 10.1% in surface soil.50% surface residue retention caused a significant increment of 15.65% in total aggregates in surface soil (0–5cm) and 7.53% in sub-surface soil (5–10 cm). In surface soil, the maximum (19.2%) and minimum (8.9%) proportion of total aggregated carbon was retained with >2mm and 0.1–0.05mm size fractions, respectively. WBed-TPR combined with zero tillage on permanent wide raised beds in wheat (with residue) (T9) had the highest capability to hold the organic carbon in surface (11.57g kg-1soil aggregates).From the study, it has been proved that higher SOC content of 8.14 g kg-1 of soil was found in reduced tilled residue retained plots followed by 10.34 g kg-1 in permanently wide raised bed with residue retained plots. Whereas, the lowest level of SOC content of 5.49 g kg-1 of soil were found in puddled transplanted rice followed by wheat planted under conventionally tilled plots. Conservation agriculture practices secure good soil health by improving soil aggregation (53.8%) and increased energy output with respect to the conventional tillage puddle transplanted rice (T10) after four years of continuous rice–wheat cropping system in a Typic Ustochreptsoil of Uttar Pradesh.