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IARRP team quantifies soil carbon sequestration effects of green manure rice fields at regional scale

IARRP | Updated: 2025-05-15

The Innovation Team of Fertilizer and Fertilization Technology at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has quantified the soil carbon sequestration capacity of green manure rice fields at a regional scale and revealed a new mechanism promoting soil carbon sequestration through the joint utilization of green manure and rice straw. The related findings were published under the title "Green manure coupled with straw returning increases soil organic carbon via decreased priming effect and enhanced microbial carbon pump" in the international Global Change Biology journal.

Farmland soils contribute to 10% of the global soil carbon reservoir. Due to the depletion of soil organic carbon (SOC) in almost all cultivated soils before reclamation, farmland is considered a potentially significant sink for recapturing carbon. Measures such as planting green manure and returning straw to the fields are widely used to enhance SOC reserves. However, while exogenous carbon inputs promote the formation of new SOC, they also accelerate the mineralization of original SOC through priming effects. Both factors collectively determine the net SOC balance, with microbial communities being the primary driving force regulating this dynamic. Therefore, understanding the synergistic mechanisms of SOC mineralization and formation is crucial for assessing the actual contributions of carbon sequestration measures.

This study utilized a network of 10 experimental sites in southern rice-growing areas of China to quantify the soil carbon sequestration rates under green manure, rice straw, and combined green manure-rice straw utilization, which were 119.7 kg C hm–2 yr–1, 477.0 kg C hm–2 yr–1, and 830.2 kg C hm–2 yr–1, respectively. The highest soil carbon sequestration efficiency was observed under the combined utilization of green manure and rice straw, at 23.1%. The study found that the efficient carbon sequestration mechanism of the combined utilization involved: adjusting the soil K-strategist bacteria, suppressing the priming effect on recalcitrant carbon such as lignin and amino sugar in the original SOC, reducing the mineralization of original SOC; driving the bacterial carbon pump dominated by r-strategist bacteria and the fungal carbon pump dominated by fungi, converting more carbon from green manure and rice straw into stable microbial residue carbon, promoting the formation of new SOC. This study represents another significant discovery following the team's revelation of the mechanisms related to the promotion of decomposition, soil nurturing, fertilizer reduction, emission reduction, and carbon sequestration through the combined utilization of green manure and rice straw. The research results provide important scientific basis for the comprehensive promotion and application of the "carbon-nitrogen mutual assistance" initiative of green manure-rice straw combined utilization and offer effective technical support for the current farmland emission reduction and carbon sequestration actions in China.

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Figure 1: Model of promoting soil carbon sequestration through the combined utilization of green manure and rice straw

Professor Zhou Guopeng from the College of Resources and Environment at Anhui Agricultural University and Assistant Researcher Li Guilong from the Jiangxi Academy of Agricultural Sciences are the first authors of the paper, with Researcher Cao Weidong from the Institute of Agricultural Resources and Regional Planning of the Chinese Academy of Agricultural Sciences as the corresponding author. The research was supported by the Key Laboratory of Efficient Utilization of Northern Arid and Semi-arid Cropland, the National Key Research and Development Program (2021YFD1700200), the National Natural Science Foundation of China (32202609, 32072678), and the National Green Manure Industry Technology System (CARS-22).

Original Link: https://doi.org/10.1111/gcb.70232