Mechanized conservation tillage is being adopted by more and more farmers in Northeast China this year. Conservation tillage, nicknamed as "lazy man's farming," refers to no-till sowing with crop residues mulch (e.g., maize straw). By the end of 2019, conservation tillage has been applied to more than 15 million mu (1 ha = 15 mu) of farmland in Northeast China.

In February 2020, the Ministry of Agriculture and Rural Affairs and the Ministry of Finance jointly issued “Northeast China's Black Land Conservation Tillage Initiative (2020-2025)," which clearly stated: "We must accelerate the promotion and adoption of conservation tillage mode, and strive to apply this tillage mode to 140 million mu of farmland by the year 2025." Why must we do this?

Northeast China's Black Land is degrading

Excessive soil reclamation and long-term traditional farming such as removing and burning of crop straw severely damaged soil structure, reduced nutrient input to soil, and exposed soil to wind and water erosion. Consequently, the organic content of the fertile black soil declined year after year. Soil degradation severely restricts the grain output and the agricultural sustainable development in Northeast China.

Scientists find out a suitable conservation tillage mode for Northeast China's Black Land

The increasingly severe problem of soil degradation attracted the attention of scientists. In 2007, ZHANG Xudong, researcher of the Institute of Applied Ecology, Chinese Academy of Sciences, led his research team members to Gaojia Village, Lishu Town, Lishu County, Jilin Province, where is "the front line" of black soil degradation. After more than ten years of research there, they created a conservation tillage system that features maize stalk mulch and mechanized no (less) till technology. The technology system integrates agronomic and agricultural machinery measures and provides a solution to black soil degradation in Northeast China.

Adoption of conservation tillage means no need to deal with crop straw, rotary tilling, or ridging. Instead, all you have to do is to mulch crop straw evenly on the ground in situ after harvest, and to conduct mechanized no-till sowing (and fertilizing) directly on the straw-covered farmland in the next spring.

Why "the lazy man's farming" is better for farmland compared to the traditional farming?

Land, like our human beings, requires care.

On the one hand, no-tillage or less tillage practices protect the original ecological characteristics of the soil and provide good living space for soil organisms, which not only promote the improvement of soil structures (for example, through increasing the numbers and diversity of soil animals and microbes), but also promote the cycling and accumulation of soil nutrients, and consequently make the black soil regain its vitality.

On the other hand, the strong wind in spring may blow away a considerable amount of organic matter in the bare soil. When using conservative tillage, the layer of crop straw cover the ground, like a "quilt," reducing wind and water erosion and increasing the retention of water in the soil. Also, this layer of the crop straw is like a "facial mask" that nourishes "the skin of the earth". It supplies a lot of water and nutrients to the soil, increases carbon storage in the soil, and reduces the use of chemical fertilizers. The cost-saving and efficiency gains in agricultural development can thus be realized.

The reason why "straw returning to the field" improve soil carbon and nutrient storage is mainly due to the assistance of soil microbes, a huge underground labor force. Further, ZHANG Xudong's team proposed mechanism insights in view of the roles of microorganisms in soil carbon and nitrogen processes. For conservation tillage, crop straw carbon is just "food" that microbes like to eat. The "food" is continuously anabolic and metabolized by "the soil microbial carbon pump." In this way, the exogenous carbon can be continuously converted into a part of the soil carbon pool. In addition, crop straw as an effective carbon source is a great help for nitrogen sequestration and transformation from inorganic fertilizers. When the carbon- and nutrient-rich straw is added to the soil, the microbial community is quickly activated, and they can produce a large amount of microbial source organic nitrogen which may continuously turnover in the soil-crop system.

Therefore, the layer of straw left on the ground not only promotes the nitrogen transformation and utilization efficiency, but also reduces the risks of fertilizer loss and leaching, saves fertilizer costs and protects groundwater sources.

Agricultural development needs not only hard-working people but also technology

In conclusion, no-tillage and straw return are not only conducive to the improvement of soil physical and chemical properties, but also to the promotion of the decomposition and transformation of carbon and nutrients by microbes. It improves general soil conditions, so that it benefits crop growth and eventually increase crop yields. Despite the nickname "lazy man's farming," the new farming mode actually conserve farmland much better than the traditional farming. Also, it saves time, efforts and costs.