Abstract
Crop residue returning (RR) is a promising option to increase soil organic carbon (SOC) storage, which is linked to crop yield promotion, ecologically sustainable agriculture, and climate change mitigation. Thus, the objectives of this study were to identify the responses of SOC storage and sequestration rates to RR in China’s croplands. Based on a national meta-analysis of 365 comparisons from 99 publications, the results indicated that RR increased SOC storage by 11.3% compared to residue removal (p < 0.05). Theoretically, when combined with low nitrogen fertilizer input rates (0–120 kg N ha−1), single cropping system, paddy-upland rotation, lower mean annual precipitation (0–500 mm), alkaline soils (pH 7.5–8.5), other methods of RR (including residue chopping, evenly incorporating, and burying) or long-term use (>10 yrs), an increase in SOC storage under RR by 11.6–15.5% could be obtained. The SOC sequestration rate of RR varied from 0.48 (Central China) to 1.61 (Southwest China) Mg C ha−1 yr−1, with a national average value of 0.93 Mg C ha−1 yr−1. Higher SOC sequestration rates enhanced crop production. However, decreases in SOC sequestration rate were observed with increases in experimental durations. The phenomenon of “C saturation” occurred after 23 yrs of RR. Overall, RR can be used as an efficient and environmentally friendly and climate-smart management practice for long-term use.
Highlights
Soil is the largest organic carbon (C) pool on earth [1]
To ensure the accuracy of the study, only studies that fulfilled the following criteria were used for this meta-analysis: (1) the experimental area was in China, and experimental duration, location, and other basic information were provided; (2) the experimental design included at least one pair of treatments with the same conditions under RR and RR removal; (3) soil organic carbon (SOC) stock data were provided or could be calculated according to the data given in the papers; (4) definite replicate numbers were provided; (5) the experiment took place under field conditions
Overall, based on 365 observations, lnR++ was calculated as 0.1072, with a 95% confidence interval (95% CI) of 0.090–0.125, indicating that SOC storage could be significantly increased by 11.3% (9.5–13.3%) under RR (p < 0.05)
Summary
Soil is the largest organic carbon (C) pool on earth [1]. The dynamics of soil organic carbon (SOC)can be used to indicate changes in SOC sequestration capacity Soil is the largest organic carbon (C) pool on earth [1]. The dynamics of soil organic carbon (SOC). The C sequestration capacity could affect soil quality and mitigation function of climate change) and crop productivity [2,3]. Due to the large SOC stock, small fluctuations may cause large changes in atmospheric CO2 concentration, affecting global climate changes. In this sense, increasing SOC sequestration is one of the most important strategies to reduce atmospheric CO2 concentrations and to mitigate the greenhouse effect [4], with a significant potential to mitigate climate change [5].
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