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 found that optimizing water management can improve the net economic benefits of green manure-rice fields. 

Their research, titled "Appropriately delayed flooding before rice transplanting increases net ecosystem economic benefit in the winter green manure-rice rotation system", has been published in the international journal "Resources, Environment and Sustainability".

In the winter idle season of southern rice fields, planting green manure can increase soil organic carbon content and rice yield, serving as an efficient and economic carbon sequestration measure. However, improper methods of returning green manure to the field can lead to increased methane emissions from rice fields, undermining the carbon sequestration benefits of green manure practices. Optimizing water management serves as an effective emission reduction measure. However, most studies on water management have focused primarily on the rice growing season. In southern rice-growing regions, frequent rainfall during the rice season can reduce the emission reduction potential during the growing period, making pre-transplant water management a potentially efficient measure to reduce methane emissions.

A two-year field experiment was conducted in a typical rice planting area in the Yangtze River Basin, implementing different irrigation timings after incorporating green manure and rice straw, to study the impact of early water management on greenhouse gas emissions. The results revealed that delaying irrigation significantly alleviated methane emissions, with the most pronounced effect seen with a 10-day delay. In this case, the greenhouse gas emission intensity was similar to the treatment without organic matter incorporation. Delayed irrigation promoted early aerobic decomposition of organic materials, reducing the soluble organic carbon concentration during the rice growing season, decreasing substrates for methane-producing bacteria, and achieving methane reduction. In addition, it significantly reduced the carbon footprint of production, promoted soil carbon sequestration, and enhanced the net economic benefits of the ecosystem. 

This research provides theoretical support for enhancing carbon sequestration and emission reduction in green manure-rice fields through optimized water management.

Doctoral student Ma Zhengbo from the IARRP and Assistant Researcher Bu Rongyan from the Soil and Fertilizer Institute of the Anhui Academy of Agricultural Sciences are joint first authors of the paper. Researcher Cao Weidong from the IARRP, Researcher Wu Ji from the Soil and Fertilizer Institute of the Anhui Academy of Agricultural Sciences, and Professor Zhou Guopeng from Anhui Agricultural University are corresponding authors. The research was supported by the National Key Laboratory for Efficient Utilization of Dryland in Northern China, the National Key R&D Program during the 14th Five-Year Plan period (2021YFD1700200), the National Natural Science Foundation of China (32202609, 32072678), and the National Green Manure Industry Technology System (CARS-22).

[Citation]: Ma, Z., Bu, R., Zhou, G., Fu, H., Sun, J., Liang, T., Cai, C., Chang, D., Ma, Q., Wu, J., Chadwick, D.R., Davey, L.J., Cao, W.D., 2024. Appropriately delayed flooding before rice transplanting increases net ecosystem economic benefit in the winter green manure-rice rotation system. Resources, Environment and Sustainability, 100173.

Original Link: https://doi.org/10.1016/j.resenv.2024.100173