IARRP team discovers milk vetch-rice straw co-Incorporation promotes efficient utilization of rice straw nitrogen
The Innovation Team of Fertilizer and Fertilization Technology of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has found that co-incorporating milk vetch with rice straw promotes the efficient utilization of rice straw nitrogen.
The findings were published under the title "Rice straw nitrogen can be utilized by rice more efficiently when co-incorporating with milk vetch" in the European Journal of Agronomy.
Returning rice straw to the fields can increase soil organic matter. However, due to its high C/N ratio, in the short term, it may lead to microbial and crop competition for soil available nitrogen. Consequently, effectively managing rice straw to promote its efficient utilization is a pressing issue. Milk vetch, as a major green manure in southern rice fields, possesses functions such as nitrogen fixation and improving nutrient use efficiency. Co-incorporating low C/N ratio milk vetch with high C/N ratio rice straw is more beneficial for regulating the decomposition rate of the materials and nutrient release process. However, the fate of milk vetch N and straw N from the rice cropping system and their contributions of the two to soil and crops are not yet clear.
This study utilized a combination of field and pot experiments, aided by 15N isotope labeling technology to study the distribution and utilization of rice straw N and milk vetch N in the rice cropping system under co-incorporation of milk vetch and rice straw. The research revealed that the co-incorporation of milk vetch and rice straw increased the average annual yield by 10.8% and 9.6% respectively compared to individual rice straw and milk vetch treatments. In comparison to individual rice straw and milk vetch incorporation, the nitrogen uptake by rice plants significantly increased by 28.9% and 13.7% in the co-incorporation treatment. Co-incorporation enhanced rice absorption of nitrogen from rice straw. In the individual rice straw treatment, 13.3% of rice straw nitrogen was absorbed by the subsequent rice crop, 32.3% was stored in the soil, and 54.4% was lost. In the co-incorporation treatment, 20.4% of rice straw nitrogen was absorbed by the subsequent rice crop, 50.2% was stored in the soil, and 29.3% was lost. Compared to the individual rice straw treatment, co-incorporation increased rice absorption of nitrogen from rice straw and nitrogen storage in the soil by 53.4% and 55.4%, respectively, while reducing nitrogen loss from rice straw by 46.1%.
Co-incorporating milk vetch with rice straw can enhance rice yield and nitrogen uptake, facilitate the decomposition of rice straw, and promote rice's absorption and utilization of nitrogen from rice straw. In rice-growing areas, the co-incorporation of milk vetch and rice straw should be encouraged to promote sustainable agricultural development and enhance green and efficient agricultural production.
Doctoral student Fan Qianyu from the College of Resources and Environmental Sciences at Nanjing Agricultural University was the first author on the study, with Researcher Cao Weidong from the IARRP and Associate Professor Gao Songjuan from Nanjing Agricultural University acting as corresponding authors. The research was supported by the National Key Laboratory for Efficient Utilization of Arid and Semi-Arid Farmland in Northern China, the "14th Five-Year Plan" National Key Research and Development Program (2021YFD1700200), and the National Green Manure Industry Technology System (CARS-22).
[Citation]: Fan Q, Xie J, Du J, et al. Rice straw nitrogen can be utilized by rice more efficiently when co-incorporating with milk vetch[J]. European Journal of Agronomy, 2025, 164: 127495.
Article Link: https://doi.org/10.1016/j.eja.2024.127495