The extent of soil loss across the US Corn Belt
The extent of soil loss across the US Corn Belt
复制标题
美国玉米种植带的土壤流失程度
DOI：
10.1073/pnas.1922375118
复制
发表时间：
2021-02-23
影响因子：
11.1
通讯作者：
Yu, Qian
中科院分区：
文献类型：
--
作者：
Thaler, Evan A.;Larsen, Isaac J.;Yu, Qian
农业景观中的土壤侵蚀降低了作物产量，导致生态系统服务的损失，并影响全球碳循环。尽管进行了数十年的土壤侵蚀研究，但在大型农业地区，历史土壤流失的程度仍然很难量化，因为农业前的土壤数据很少，而且很难在时间和空间上推断出当地规模的侵蚀观测结果。在这里，我们专注于美国中西部的玉米带，并使用遥感方法来绘制农田中没有剩余的富含有机碳的A层的区域。我们使用卫星和激光雷达数据来建立A层损失和地形曲率之间的关系，然后使用地形数据来扩大玉米带3.9 x 10（5）km（2）的土壤流失预测。我们的研究结果表明，35 +/- 11%的耕地面积已经失去了A层土壤和土壤调查为基础的方法，土壤退化的先验估计显着低估了A层土壤流失。整个地区的凸山顶经常完全没有A层土壤。土壤流失和凸形地形之间的关联表明，耕作引起的侵蚀是土壤流失的一个重要驱动因素，但在美国，用于评估全国土壤流失趋势的模型中没有模拟耕作侵蚀。我们估计，A层损失使作物产量下降6 +/-2%，造成28 +/-9亿美元的年度经济损失。在区域范围内，我们估计1.4 +/- 0.5 Pg的碳已经通过A层的侵蚀从山坡上消失，其中大部分可能仍然埋在油田内的沉积区。
Soil erosion in agricultural landscapes reduces crop yields, leads to loss of ecosystem services, and influences the global carbon cycle. Despite decades of soil erosion research, the magnitude of historical soil loss remains poorly quantified across large agricultural regions because preagricultural soil data are rare, and it is challenging to extrapolate local-scale erosion observations across time and space. Here we focus on the Corn Belt of the midwestern United States and use a remote-sensing method to map areas in agricultural fields that have no remaining organic carbon-rich A-horizon. We use satellite and LiDAR data to develop a relationship between A-horizon loss and topographic curvature and then use topographic data to scale-up soil loss predictions across 3.9 x 10(5) km(2) of the Corn Belt. Our results indicate that 35 +/- 11% of the cultivated area has lost A-horizon soil and that prior estimates of soil degradation from soil survey-based methods have significantly underestimated A-horizon soil loss. Convex hilltops throughout the region are often completely denuded of A-horizon soil. The association between soil loss and convex topography indicates that tillage-induced erosion is an important driver of soil loss, yet tillage erosion is not simulated in models used to assess nationwide soil loss trends in the United States. We estimate that A-horizon loss decreases crop yields by 6 +/- 2%, causing $2.8 +/- $0.9 billion in annual economic losses. Regionally, we estimate 1.4 +/- 0.5 Pg of carbon have been removed from hillslopes by erosion of the A-horizon, much of which likely remains buried in depositional areas within the fields.