Climate change could reshape the future of Chinese milk vetch in southern rice paddies
Machine learning reveals critical temperature and rainfall thresholds for one of China’s most important winter green manure crops
image:
Spatial patterns and climate-driven factors of Chinese milk vetch biomass in southern China's rice paddies
view moreCredit: Xiaoyue Wu, Hao Liang, Ruidong Chen & Songjuan Gao
Chinese milk vetch, a leguminous crop widely planted in rice paddies during winter, plays an important role in supplying nitrogen, building soil carbon, and reducing reliance on synthetic fertilizers. A new study has now mapped how its biomass varies across southern China and identified where future climate change may place this valuable green manure crop under the greatest pressure.
Using 572 field measurements from 111 monitoring sites across 13 provinces, researchers combined a Random Forest machine learning model with SHAP, an interpretable artificial intelligence method, to determine how geography, soil properties, temperature, rainfall, humidity, and sunshine influence Chinese milk vetch biomass.
“Chinese milk vetch is more than a winter cover crop. Its biomass directly affects how much biologically fixed nitrogen and organic carbon can be returned to rice fields,” said corresponding author Hao Liang of Hohai University. “Our results show that climate does not affect this crop in a simple linear way. There are clear temperature and precipitation ranges within which milk vetch performs best, and these thresholds can help guide more precise regional management under a changing climate.”
The researchers found that the average dry biomass of Chinese milk vetch was 3.23 metric tons per hectare. At the regional scale, the highest biomass was concentrated in the middle and lower reaches of the Yangtze River, particularly in areas such as Hunan, Hubei, and Jiangxi. Lower biomass was found in parts of southern and southwestern China.
The machine learning model explained 68% of the observed spatial variation. Importantly, climatic factors accounted for 40.5% of biomass variation, compared with 31.7% for geographic factors and 27.8% for soil factors.
The analysis also uncovered strong nonlinear climate thresholds. Growing-season precipitation between approximately 533 and 877 millimeters was associated with favorable biomass accumulation, while rainfall below or above this range was linked to reduced growth. Mean growing-season temperatures of about 10.7 to 13.7°C formed a broad thermal buffer, while temperatures above 13.7°C were increasingly associated with heat stress and lower biomass.
To explore what these relationships could mean in the future, the team combined its biomass model with projections from three CMIP6 climate models under four Shared Socioeconomic Pathway scenarios. Across southern China as a whole, milk vetch biomass was projected to decline by roughly 2% to 4% by 2098, but the regional picture was far more uneven.
The Huang Huai Hai single-cropping rice region was projected to experience some of the largest losses, reaching about 13% to 14% under higher-emission scenarios. In contrast, the middle and lower Yangtze River double-cropping region remained comparatively stable and could see biomass increases of approximately 1.9% to 5.9% under some scenarios.
These contrasting responses suggest that a single management strategy will not be suitable everywhere. The authors propose region-specific approaches, including adjusting sowing dates, developing stress-tolerant varieties in vulnerable areas, conserving soil moisture, and optimizing the integration of milk vetch with rice straw and nitrogen management.
The findings provide a climate-informed framework for deciding where Chinese milk vetch cultivation can remain resilient and where additional adaptation measures may be needed. They also provide field-based benchmark data that could support crop modeling and remote sensing studies aimed at improving green manure management across southern China.
===
Journal Reference: Wu X, Liang H, Chen R, Gao S. 2026. Spatial patterns and climate-driven factors of Chinese milk vetch biomass in southern China's rice paddies. Agricultural Ecology and Environment 2: e024 doi: 10.48130/aee-0026-0022
https://www.maxapress.com/article/doi/10.48130/aee-0026-0022
===
About Agricultural Ecology and Environment:
Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.
Follow us on Facebook, X, and Bluesky.
Journal
Agricultural Ecology and Environment
Method of Research
Experimental study
Article Title
Spatial patterns and climate-driven factors of Chinese milk vetch biomass in southern China's rice paddies
Article Publication Date
28-Sep-2026
No comments:
Post a Comment