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Bulletin of Chinese Academy of Sciences (Chinese Version)

Keywords

Black Soil, carbon loss, crop productivity, soil fertility improvement

Abstract

Carbon-rich Black Soils are an important natural resource ensuring China’s food security, and their soil carbon stocks are closely related to grain production capacity. Based on nearly two decades of regional survey data and long-term field experiments, this study systematically investigated the dynamics of soil organic matter (SOM), its response relationship with crop productivity, and strategies for soil fertility improvement. The results showed that soil carbon stocks in the topsoil (0–20 cm) of the Black Soil region in Northeast China have declined by approximately 60%. In 2019, the regional average SOM content was approximately 36 g/kg and was decreasing at an average annual rate of 0.3%, although this declining trend is expected to eventually stabilize at a climate-regulated equilibrium point. A significant unimodal relationship was identified between SOM content and maize yield, with the maximum yield achieved at an SOM threshold of 70 g/kg, indicating that the natural productivity of Black Soils has declined by approximately 20%. This study is the first to quantitatively establish target SOM levels for Black Soil fertility improvement, providing a scientific basis for the targeted restoration of degraded Black Soils and the recovery of soil fertility. Significant differences were observed among soil fertility improvement practices. The application of organic fertilizers or mineral humic substances can rapidly increase SOM content at a cost of CNY 24000–36840 per hectare. In contrast, continuous straw mulching and incorporation for more than seven years can effectively increase carbon storage throughout the 1 m soil profile, with an average annual carbon sequestration rate of 0.89%. Maintaining adequate soil carbon stocks is essential for sustaining the grain production capacity of Black Soils, and increasing organic carbon inputs represents a necessary, effective, and practically feasible approach to soil fertility improvement. Therefore, it is recommended that an SOM content of 45 g/kg, corresponding to a 10% decline in natural productivity, be adopted as the warning threshold for Black Soil degradation, while an SOM content of 70 g/kg, corresponding to the maximum maize yield, should be established as the target level for the fertility restoration of degraded Black Soils. These findings provide a scientific basis for the implementation of China’s Black Soil Conservation Program and the national strategy of “storing grain in the land”.

First page

1527

Last Page

1534

Language

Chinese

Publisher

Bulletin of Chinese Academy of Sciences

References

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