Temporal variability of soil organic carbon in paddies during 13‐year conservation tillage

Abstract

AbstractDecreasing temporal variability of soil organic carbon (SOC) can avoid its temporary loss, which is positive to SOC accumulation and mitigation of climate change. Thus, this study was designed to analyze the temporal variability of SOC stock during 13‐year tillage practices and its driving factors in rice paddies of Southern China. Four tillage practices were studied: no‐till (zero‐tillage) with residues retained on the soil surface (NTS, conservation tillage), rotary tillage with incorporated residues (RTS), moldboard plow tillage with incorporated residues, or with residues removed. The SOC stock at 0–30 cm soil depth varied widely between 2007 and 2017, partly due to the annual temperature and precipitation variations. The temporal variation of SOC was lower under NTS than other tillage practices (p < .05). This was associated with the lower variation of heavy SOC and mineral associated SOC as well as with lower (p < .05) potential mineralizable carbon under NTS. Despite SOC saturated in all treatments, NTS increased (p < .05) the SOC content by 12.1%–35.3% at 0–5 cm soil depth. Thus, NTS in double rice paddies has been proved to be a promising option to maintain high levels of soil C accumulation with low temporal variability, especially at the upper 0–5 cm depth.