Straw mulching helps to protect black soil

Developing conservation tillage with improved farming techniques and agricultural machinery can increase grain production on the black soil in Northeast China, protect land resources and increase farmers' incomes, agricultural experts say.

On Monday — Black Soil Conservation Day in Jilin province — more than 300 agricultural experts from home and abroad, including major black soil areas in the world such as the United States and Russia, gathered in Changchun, the provincial capital, to discuss topics related to the conservation and utilization of black soil.

"Black soil is a precious agricultural resource," said Professor Jia Zhongjun from the Chinese Academy of Sciences' Northeast Institute of Geography and Agroecology. "With a large population and limited land, China is under pressure to feed its people. Therefore, great emphasis has been placed on the development and protection of black soil, accumulating rich farming techniques and experiences. We hope to exchange ideas with agricultural experts from around the world."

China is one of the world's four typical black soil regions, with approximately 50 million hectares of black soil mainly concentrated in Northeast China.

"Black soil feeds the world," said Tong Yuxing, an official from the Food and Agriculture Organization of the United Nations.

However, despite being a major grain-producing region in China, the organic matter content in the topsoil of the black soil region in Northeast China has decreased by over 50 percent in the past 100 years.

The average thickness of the black soil layer has decreased from about 50 centimeters to around 30 cm, and it is still declining at an annual rate of 0.05 percent, according to research by the institute.

Strengthening agriculture, benefiting farmers and enriching rural areas were underlined in the Resolution of the Central Committee of the Communist Party of China on Further Deepening Reform Comprehensively to Advance Chinese Modernization adopted at the third plenary session of the CPC's 20th Central Committee last week.

In July 2020, CAS launched a "Black Soil Granary" scientific campaign. Seven farmland demonstration areas were established in the provinces of Jilin, Heilongjiang and Liaoning and the Inner Mongolia autonomous region, including Lishu, Da'an, Longjiang and Dahewan.

Through collaboration among research institutions, government agencies and enterprises, conservation tillage has been developed based on modern farming techniques and has been applied to 18 million hectares of farmland, Jia said.

Straw mulching is the core of conservation tillage.

"Under different temperature and humidity conditions in different regions, we have explored three methods of handling straw — covering, mixing and burying — to accelerate decomposition and increase soil organic matter content," Jia said.

Taking the demonstration area in Lishu county, Siping, Jilin, as an example, after harvesting corn, the harvester scatters all the straw on the ground to cover the land, reducing environmental pollution caused by traditional burning, as well as soil erosion and sand blowing. By the following spring, the straw naturally decomposes into organic fertilizer, Jia said.

"However, if the straw is scattered on the ground, it will affect the planting in the second year," he said. "Therefore, we have independently developed a seeder that can gently open the surface without destroying the straw cover as much as possible and sow seeds next to the planting points from the previous year.

After a field trip to Lishu last week, Michael Thompson, a professor at Iowa State University in the US, said: "It could improve the management of crop residues on the surface and improve the incorporation of the residues in the soil. The machinery was really new to me and very interesting, so I'll take those ideas back with me to the US."

Thompson, who is also president of the Soil Science Society of America, said, "Increasing communication between scientists in the US and China, and other countries around the world, is really advantageous for us."

Steffen Kolb, an agricultural professor at Humboldt University of Berlin, said: "When we think of sustainability, we might minimize economic outputs. But I'm very impressed that in northeastern China, I saw people protect soil on a large scale but also figure out how to guarantee the produce."

Kolb said that China plays an important role in global food security due to its high agricultural productivity capacity, praising China's efforts in building a strong foundation of science and technology in agriculture.

"Through more communication and cooperation, we can share the technologies and ideas that we develop with regions facing food scarcity," he said.