Abstract. The straw return practice is essential to soil organic matter (SOM) accumulation in the black soil area with high carbon sequestration potential. However, due to lacking accurate spatial distribution of straw return, few studies took straw return as a variable to carry out rigorous research on the impact of straw return on SOM variation on a regional scale. Based on soil samples and 16 environmental covariates including a 10-meter-resolution straw return amount, the study mapped the spatial distributions of SOM in 2006 and 2018 by random forest (RF) and evaluated the effects of the interaction of soil properties, land use and straw return on SOM spatial-temporal variation. The results show that in the context of the straw returning, the mean SOM content increased from 18.93 g kg⁻¹ to 20.84 g kg⁻¹ during 2006–2018. And 74.49 % of the region had a significant increase (maximum: 24.41 g kg⁻¹) of SOM. The severest SOM loss occurred in the northwest due to the light texture and the transition from paddy fields to dryland. Nevertheless, for areas from paddy fields to dryland, the SOM loss decreased with the increased amount of straw return. The SOM even increased by 1.84 g kg⁻¹ when the straw return amount reached 60–100 %. In addition, soil with higher initial SOM and sand content had a lower response to straw return. The study revealed that straw return is beneficial to carbon sink in farmland and is a better way to prevent a carbon source caused by the change of paddy field to dryland.

中文翻译：

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长期秸秆还田对土壤有机质时空变化影响的量化——以典型黑土区为例

摘要。秸秆还田实践对于具有高碳封存潜力的黑土区的土壤有机质 (SOM) 积累至关重要。然而，由于秸秆还田缺乏准确的空间分布，很少有研究将秸秆还田作为变量，在区域尺度上对秸秆还田对土壤有机质变化的影响进行严谨的研究。基于土壤样本和包括 10 米分辨率秸秆还田量在内的 16 个环境协变量，该研究通过随机森林 (RF) 绘制了 2006 年和 2018 年 SOM 的空间分布，并评估了土壤性质、土地利用相互作用的影响。和 SOM 时空变化的秸秆回报。结果表明，在秸秆还田的情况下，平均 SOM 含量从 18.93 g kg ^-1增加2006-2018 年期间增至 20.84 g kg ^{-1 。}并且该地区 74.49 % 的 SOM 显着增加（最大：24.41 g kg ^-1）。由于质地较轻以及从稻田向旱地的过渡，西北部的土壤有机质损失最为严重。然而，对于从稻田到旱地的地区，SOM 损失随着秸秆还田量的增加而减少。当秸秆还田量达到 60-100% 时，SOM 甚至增加了 1.84 g kg ^{-1 。}此外，初始 SOM 和沙含量较高的土壤对秸秆还田的响应较低。研究表明，秸秆还田有利于农田碳汇，是防止稻田转旱造成碳源的较好途径。