Against the backdrop of global warming, agricultural carbon neutrality has become a core issue of international concern. As the world’s largest grain producer, China's farmland must not only ensure food supply for 1.4 billion people but also address the environmental pressure caused by agricultural greenhouse gas emissions. So, how can we achieve carbon emission reduction through optimized farmland management while ensuring food security?

Recently, a review study led by Professor Xuejun Liu from the College of Resources and Environmental Sciences at China Agricultural University and Tianxiang Hao et al. systematically analyzed the current status of China’s farmland carbon budget, providing a scientific solution to this dilemma. The related paper has been published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025602).

The study shows that China’s farmland ecosystem exhibits the dual characteristics of a “weak carbon sink and strong emissions”. From 1990 to 2015, farmland greenhouse gas emissions increased at an annual rate of 4.3 Tg CO₂-eq, peaking at 400 Tg CO₂-eq in 2015. Since then, through management optimization, emissions decreased by an average of 11.6 Tg CO₂-eq per year from 2015 to 2021, dropping to 340 Tg CO₂-eq in 2021. Despite the slowed emission growth, farmland remains a significant source, accounting for 50.3% of total agricultural emissions and 3.6% of the country’s total emissions.

In terms of carbon sequestration capacity, the organic carbon storage in the topsoil (0–30 cm) of China’s farmland reaches 5.5 Pg. Since the 1980s, it has accumulated at an annual rate of 21.3 Tg C, equivalent to absorbing 78 Tg CO₂ per year. However, soil inorganic carbon loss is severe, with an annual loss of 16 Tg C, offsetting approximately 75% of the organic carbon sink effect. This imbalance between “carbon sink and emission” highlights the complexity of farmland carbon management.

The study points out that optimizing farmland management is the core path to achieve carbon emission reduction. In terms of nitrogen fertilizer management, the utilization rate of nitrogen fertilizer in China’s farmland is only 25%–40%, lower than the international average. Through “4R nutrient management” (right fertilizer type, rate, time, and place), replacing part of chemical fertilizers with organic fertilizers combined with straw returning can increase soil organic carbon content by 9%–39%.

Improvements in irrigation and tillage techniques have also achieved significant results. Traditional flooded rice cultivation releases large amounts of methane, while the “alternate wetting and drying” irrigation technique can reduce methane emissions by 37%. If conservation tillage such as no-tillage and cover cropping is promoted nationwide, the farmland carbon sequestration capacity can be increased to 4.6 Tg C per year, equivalent to one-fifth of the current carbon sink.

Despite the clear technical potential, the application rate of existing measures remains low. Data shows that organic fertilizers account for only about 10% of nitrogen fertilizer application, the straw returning rate is about 40%, and the area under conservation tillage is less than 10% of the total cultivated land. The study suggests that policy guidance and technical training are needed to promote the implementation of integrated management models. Meanwhile, farmland carbon neutrality must take regional differences into account. In arid areas of North China, soil inorganic carbon contributes even more to carbon sequestration than organic carbon, while southern rice fields need to focus on controlling methane emissions. In the future, it is also necessary to cultivate high-carbon-sink crop varieties and develop low-carbon agricultural machinery to promote green transformation across the entire industry chain.
DOI: 10.15302/J-FASE-2025602