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 uncovered the mechanism by which long-term green manuring enhances soil carbon sequestration. The related findings, titled "Long-term green manuring increases soil carbon sequestration via decreasing qCO₂ caused by lower microbial phosphorus limitation in a dry land field," have been published in the international journal "Agriculture, Ecosystems & Environment."

Proper fertilizer management can not only ensure crop yields but also promote soil carbon sequestration. Imbalanced fertilization, such as excessive or insufficient nutrient inputs (carbon, nitrogen, and phosphorus), alters microbial metabolic activities, leading to the decomposition of soil organic carbon and weakening the soil's carbon sequestration capacity. Considering the effects of fertilization on microbial nutrient metabolic efficiency and carbon turnover and focusing on the relationship between microbial metabolic quotient and soil carbon sequestration, provides theoretical support for understanding how fertilization management impacts soil carbon sequestration.

According to the study, fertilization significantly increased soil nutrient content in comparison to no fertilization. However, chemical nitrogen fertilizer only increased chemical nutrients in the soil but exacerbated microbial nutrient limitation, by reducing microbial carbon utilization efficiency. Green manure, cattle manure, and wheat straw effectively increased soil microbial carbon utilization efficiency, and it alleviated microbial phosphorus limitation in the 0-20 cm soil layer, and reduced microbial metabolic quotient. Under green manuring treatment, microbial phosphorus limitation and carbon limitation were minimized. Meanwhile, microbial carbon utilization efficiency was higher, whilst microbial metabolic quotient was lower, and soil carbon sequestration efficiency was also higher. Green manuring enhances phosphorus metabolism enzyme activity and reduces microbial phosphorus limitation, it converts more carbon into microbial carbon, improves microbial carbon utilization efficiency, and promotes soil carbon sequestration.

Ph.D. student Ma Zhengbo and postdoctoral researcher Liang Ting are co-first authors of the paper, with IARRP Researcher Cao Weidong and Professor Zhou Guopeng from Anhui Agricultural University as corresponding authors. The research was supported by the National Key Laboratory for Efficient Utilization of Northern Arid and Semi-arid Cropland, the National Key Research and Development Program during the 14th Five-Year Plan (2021YFD1700200), and the National Green Manure Industry Technology System (CARS-22).

[Citation]: Ma, Z., Liang, T., Fu, H., Ma, Q., Chang D., Zhang J., Che Z., Zhou, G.*, Cao, W*. 2024. Long-term green manuring increases soil carbon sequestration via decreasing qCO2 caused by lower microbial phosphorus limitation in a dry land field. Agriculture, Ecosystems & Environment, 374: 109142.

Paper Link: https://doi.org/10.1016/j.agee.2024.109142.