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Low-carbon Rice Farming: A “Golden Key” to Green Agriculture

A good harvest depends on the spring sowing. These days, the rice is ripe on the both sides of the Yangtze River, and it is the harvest season for farmers again.
Rice is widely grown in China. While feeding people, rice production also contributes to a large amount of greenhouse gas emissions. How to reconcile high rice yield with environmental protection?
To solve the problem, Professor Cao Cougui, a doctoral supervisor of The College of Plant Science and Technology, Huazhong Agricultural University, and his team made a beneficial exploration. They proposed a low-carbon rice farming strategy of “increasing sink, reducing emissions, reducing consumption and recycling”, to balance high rice yield and high efficiency with green and low-carbon environmental protection.

The experimental field of "Effect of no-till and straw return on carbon emission and carbon fixation". Photo by Huazhong Agricultural University

Rice production has dual functions of carbon sink and carbon source. Carbon sink is the synthesis of atmospheric carbon dioxide and water-synthesized carbohydrates stored in the plant by photosynthesis of rice, and the transfer of carbon to soil in the form of stubble, straw and litter. Carbon sources are direct carbon emissions such as carbon dioxide and methane generated by respiration of rice, soil and microorganisms, and indirect carbon emissions generated by seed, fertilizer, pesticide, agricultural film, machinery and fuel production and transportation.
Cao believed that the process of carbon cycling and transformation in farmland is directly and indirectly affected by agronomic measures of rice cultivation, whether it is carbon sink or carbon source. In order to strengthen the biological cycle of carbon and control the geochemical cycle of carbon, increasing sink and decreasing source of rice production through agronomic measures are the direction of green development of rice industry.
Cao Cougui pointed out that exerting the carbon sink function of rice production to a greater extent would be an important part of promoting green, low-carbon and high-quality development of rice. Based on the theory of low-carbon rice farming, he and his team have developed a "climate-soil-crop collaborative system", the core of which is to build a strong soil carbon pool. The combination of organic and inorganic fertilizers, minimum tillage, no-tillage and mulching that he advocated can increase the soil carbon pool continuously.
Just like the two sides of the coin, farming, fertilization, irrigation and other agronomic measures have a double-sided impact on soil carbon cycle, on the one hand, carbon fixation, and on the other hand, carbon emissions. Carbon sequestration is greater than carbon emissions, which means carbon surplus. If the carbon surplus is greater, the carbon neutralization level will be higher. In Cao's view, agronomic measures such as minimum tillage, straw returning, reduced nitrogen application, intermittent irrigation and paddy planting can all help a carbon surplus.

Cao Cougui (third from right in the first row) and his research team. Photo by Huazhong Agricultural University

Recently, the Ministry of Agriculture and Rural Affairs and other relevant departments has the 14th Five-year Plan for The Green Development of Agriculture. According to the plan, by 2025, the intensity of greenhouse gas emissions from major agricultural products will be significantly reduced, the capacity of agriculture to reduce emissions, fix carbon and cope with climate change will be enhanced, and the efficiency of agricultural energy use will be effectively improved. Professor Cao Cougui believes that studying different land use at regional scale, the effects of carbon sequestration and emission reduction, as well as the regulation of related technologies and policies, can better assist in the realization of the “dual carbon” goal.

Translated by: Lei Mengfan
Supervised by: Zhang Juan