Contour Farming Suitability of the Black Soil Region in Northeast China and Its Spatial Characteristics

Contour farming technology plays a key role in reducing soil erosion, enhancing water use efficiency, and fostering sustainable agricultural development. Despite being a straightforward yet efficacious farming technique, it has not seen widespread implementation in China. Considering the deteriorating quality of arable lands in the Black Soil Region of Northeast China (BSR-NEC), it is necessary to investigate spatial patterns and identify suitable areas for contour farming in this region. To achieve this objective, spatial autocorrelation and grouping analysis methods were employed to classify the land into four categories of suitability for contour farming: highly suitable, moderately suitable, generally suitable, and unsuitable. The results reveal that: 1) the contour farming suitable area in BSR-NEC covers 89 861.32 km2, accounting for 21.59% of arable land as of 2020. Heilongjiang Province owns the largest suitable area of 32 853.68 km2, and Inner Mongolia has the highest proportion of 28.89%. 2) In terms of the spatial distribution, regions with higher suitability for contour farming are concentrated in the Da Hinggan Mountains region, particularly Nenjiang City (Heilongjiang Province), which has the highest area of 2593.07 km2. Areas with a high proportion of suitable arable lands for contour farming are mainly found in the Da Hinggan Mountains and Changbai Mountains regions, with Ergun City (Inner Mongolia) having the highest proportion at 47.2%. Regions with higher suitability and proportion are concentrated in the Da Hinggan Mountains region, primarily covering the Inner Mongolia and Heilongjiang. 3) Regarding spatial clustering, both the area and proportion of suitable contour farming areas exhibit noticeable clustering effects, though not entirely consistent. 4) Group analysis results designate 148 counties in BSR-NEC as highly suitable areas, predominantly located in the Changbai Mountains region, Liaodong Peninsula, Hulun Buir Plateau, and the north and south regions of the Da Hinggan Mountains. The zoning of suitable areas for contour farming in BSR-NEC informs the strategic development of policies and measures, allowing for the implementation of targeted policies in distinct areas suitable for contour farming. This provides a valuable reference for promoting contour farming technology more effectively and efficiently.re effectively and efficiently.