Analysis of conservation practices for black soil based on organic matter and nitrogen contents in the black soil region of Northeast China.

Black soil conservation has attracted increasing attention from researchers. However, few studies have addressed black soil degradation and conservation mechanisms in the black soil region of Northeast China. In this study, we investigated black soil in Bei'an City in Heilongjiang Province and conducted comparisons with soil in other locations with similar environmental conditions and agricultural production levels but different reclamation histories. We predicted and analyzed the changes in the organic matter and nitrogen contents of black soils after different numbers of years under reclamation by using a gray forecast model. In addition, we aimed to identify soil conservation practices that consider the physical, chemical, and microbial properties of soils in the black soil region of Northeast China for implementation in the long term. The results showed that human and natural factors, such as long-term unsustainable cultivation practices and soil erosion, have caused the structural degradation of black soil in Northeast China. The annual decreases in the organic matter and nitrogen contents of black soil in Bei'an City were determined as 0.17% and 0.18%, respectively, using the gray forecast model. Preliminarily explorations identified the potential mechanisms associated with the effects of soil conservation practices on the organic matter and nitrogen contents, and microbial dynamics in black soils. Finally, according to the current implementation of black soil conservation practices in the black soil region of Northeast China, the outlook for future soil conservation practices is reasonable. This study provides a theoretical reference to meet the aims of protection and utilization for black soil in Northeast China in the future.