Soil erosion is a principal mechanism of land degradation, and wind erosion is particularly marked in northeast China due to its ecological characteristics. However, most investigations on the implications of land degradation on soil quality and crop productivity have concentrated on water-erosion regions, and little focus has been placed on the wind-erosion region. Therefore, we examined the impacts of land degradation on soil quality and crop productivity in the degradation area of Horqin Sandy Land, the wind-eroded region of northeast China, which suffers from varying intensities of land degradation, that is, no degraded grassland, lightly, moderately, and severely degraded croplands. In our study, network analysis (NA) was applied as a novel approach to calculate the soil quality index (SQI), which covered 11 physical, 12 chemical, and 6 biological variables measured in the 0–20 cm soil layer as indicators of soil quality. Results showed that land degradation resulted in adverse effects on soil properties. SQI, crop yield, and above-ground biomass significantly decreased with land degradation increasing (P < 0.05). Specifically, the result of NA showed soil organic carbon, microbial biomass carbon, and bulk density (BD) were the most responsive factors impacting SQI under land degradation. Structural equation modeling showed that land degradation led to the reduction of crop productivity by altering soil properties and then changing SQI. Soil physical properties were the best mediator for the indirect effects of land degradation on SQI. In addition, the BD increased, but clay, soil total nitrogen, and organic matter content decreased from 1981 to 2022, which reveals land degradation in this area. Our investigation provides a theoretical foundation for preserving cropland in wind-eroded areas of northeast China.

中文翻译：

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土地退化通过改变网络分析生成的土壤质量指数来降低作物生产力


水土流失是土地退化的主要机制，由于其生态特性，风蚀在东北地区尤为明显。然而，关于土地退化对土壤质量和作物生产力影响的大多数研究都集中在水蚀地区，而很少关注风蚀地区。因此，本文研究了东北风蚀区科尔沁沙地退化区土地退化对土壤质量和作物生产力的影响，该退化区遭受了不同程度的土地退化，即无退化草地，轻度、中度和重度退化农田。在我们的研究中，网络分析 （NA） 被用作计算土壤质量指数 （SQI） 的新方法，它涵盖了在 0-20 厘米土壤层中测量的 11 个物理变量、12 个化学变量和 6 个生物变量，作为土壤质量的指标。结果表明，土地退化对土壤特性造成不利影响。随着土地退化程度的增加，SQI、作物产量和地上生物量显著下降（P < 0.05）。具体而言，NA 结果表明，土壤有机碳、微生物生物量碳和容重 （BD） 是土地退化下影响 SQI 的最敏感因子。结构方程模型表明，土地退化通过改变土壤特性，然后改变 SQI 导致作物生产力降低。土壤物理性质是土地退化对 SQI 间接影响的最佳中介。此外，从 1981 年到 2022 年，BD 增加，但粘土、土壤全氮和有机质含量下降，这表明该地区的土地退化。 本研究为东北风蚀区农田保护提供了理论基础。