Rates of Historical Anthropogenic Soil Erosion in the Midwestern United States
Rates of Historical Anthropogenic Soil Erosion in the Midwestern United States
复制标题
DOI：
10.1029/2021ef002396
复制
发表时间：
2022-03-01
期刊：
影响因子：
8.2
通讯作者：
Larsen, Isaac J.
中科院分区：
文献类型：
--
作者：
Thaler, Evan A.;Kwang, Jeffrey S.;Larsen, Isaac J.
侵蚀使土壤退化，降低作物产量，减少生态系统服务。在大多数农业景观中，自开始耕作以来已被侵蚀的土壤总量是未知的，这阻碍了对土壤侵蚀趋势的评估。在美国中西部，水土流失导致原生草原的残余物凌驾于周围农田之上，这为测量历史土壤侵蚀率提供了机会。我们利用高分辨率地形调查在20个草原和邻近农田边界的侵蚀悬崖上进行，显示土壤厚度的中位数减少范围为0.04至0.69 m，对应于0.2-4.3 mm /年（,）（-1）的侵蚀速率，中位数为1.9 mm /年（-1）。我们利用测量的土壤厚度减少和地形曲率之间的关联来预测从农业开始到现在的区域土壤侵蚀。我们估计历史侵蚀率中值为1.8 +/- 1.2 mm /年（-1），这几乎是美国农业部（USDA）认为可容忍的速度的两倍。目前，美国农业部国家资源清单（NRI）和每日侵蚀项目（DEP）的土壤流失预测分别比历史平均侵蚀率低3倍和8倍。我们认为，NRI和DEP低估了土壤损失率，因为它们没有包括耕作侵蚀，这一过程在美国中西部被证明是重要的。我们的研究结果表明，需要进一步实施保护措施，以降低我们测量到的高百年平均土壤侵蚀率到可持续的水平。
Erosion degrades soils, reduces crop yields, and diminishes ecosystem services. The total amount of soil that has been eroded since the initiation of farming is unknown in most agricultural landscapes, which hinders assessment of soil erosion trends. In the Midwestern U.S., erosion has caused native prairie remnants to become perched above surrounding farmland, providing an opportunity to measure historical soil erosion rates. We use high-resolution topographic surveys conducted across erosional escarpments at the boundary between 20 prairies and adjacent agricultural fields and show the median reduction in soil thickness ranges from 0.04 to 0.69 m, corresponding to erosion rates of 0.2-4.3 mm year(,)(-1) with a median value of 1.9 mm year(-1). We used an association between the measured reduction in soil thickness and topographic curvature to predict regional soil erosion integrated since the beginning of farming to the present. We estimate a median historical erosion rate of 1.8 +/- 1.2 mm year(-1), which is nearly double the rate considered tolerable by the U.S. Department of Agriculture (USDA). Current soil loss predictions from the USDA National Resources Inventory (NRI) and the Daily Erosion Project (DEP) are lower than our historically averaged erosion rate by a factor of 3 and 8, respectively. We suggest that the NRI and the DEP underpredict soil loss rates because they do not include tillage erosion, a process shown to be important throughout the Midwestern U.S. Our findings indicate that further implementation of conservation practices is needed to reduce the high centennial-averaged soil erosion rates that we measure to sustainable levels.