The Fertilizer and Fertilization Technology Innovation Team at the Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (IARRP) recently discovered that the combined application of green manure and biochar can improve soil quality and significantly mitigate the carbon footprint of maize farmland under a 30% reduction in nitrogen fertilizer use. The findings were published in the journal Farming System.

Excessive use of chemical fertilizers has long supported high crop yields but it has also led to soil degradation and increased greenhouse gas emissions. Achieving stable crop production while reducing chemical nitrogen inputs, improving soil quality, and enhancing ecological benefits remains a key challenge for green agricultural development. Green manure, as a clean organic fertilizer source, can improve soil fertility and enhance carbon sequestration, but its environmental benefits vary across regions when applied alone. Biochar, on the other hand, can improve soil structure and reduce greenhouse gas emissions, yet its relatively high cost limits large-scale application. Whether combining them withreduced nitrogen input, can overcome these limitations and deliver both agronomic and environmental benefits requires further investigation.

Based on a long-term field experiment in Wuwei, Gansu province, the research systematically evaluated maize growth, soil physicochemical properties, and greenhouse gas emissions, and conducted a comprehensive assessment of soil quality, carbon footprint, and eco-economic benefits. The results show that intercropping with green manure under a 30% nitrogen reduction can maintain maize productivity, while the addition of biochar further enhances aboveground biomass and nitrogen uptake.

Compared with conventional nitrogen application, the combined treatment significantly increased soil organic matter, nitrate nitrogen, available phosphorus, and microbial biomass carbon, raising the soil quality index by 29.2%. At the same time, it effectively reduced carbon dioxide and nitrous oxide emissions, thereby lowering global warming potential. In terms of carbon footprint, the treatment improved net primary productivity and increased carbon input through biochar, enhancing the net ecosystem carbon budget and reducing overall carbon footprint. Coupled with higher crop yields and reduced carbon-related costs, the approach resulted in improved net eco-economic benefits.

This study provides solid scientific evidence for achieving multiple goals—stable crop production, soil improvement, and carbon emission reduction—through the synergistic use of green manure and biochar with reduced nitrogen input, particularly in arid and semi-arid regions of northwest China.

The study was co-authored by Liu Rui from Shanxi Agricultural University and Assistant Researcher Chang Danna from IARRP as co-first authors, with Researchers Cheng Yonggang from Shanxi Agricultural University and Cao Weidong  from IARRP serving as corresponding authors. The research was supported by the National Key Research(2021YFD1700200) and Development Program during the 14th Five-Year Plan period and the China Green Manure Industry Technology System (CARS-22).

Citation:

Liu R, Chang D N, Zhang J D, Li R, Wu J J, Liang H, Cheng Y G and Cao W D. 2025. Co-utilization of green manure and biochar with 30% nitrogen reduction improves soil quality and mitigates carbon footprint. Farming System, 4, 100190.

Original Link:https://doi.org/10.1016/j.farsys.2025.100190.