Water and Soil Resources Research, Institute of Geography, University of Augsburg, Augsburg, Germany.
Department of Engineering, Federal University of Lavras, Lavras, Brazil.
Sci Total Environ. 2023 Aug 25;888:164119. doi: 10.1016/j.scitotenv.2023.164119. Epub 2023 May 13.
Centre-pivot systems are widely used for irrigation in agriculture. However, excessive water application rates under low pressure centre-pivot systems can lead to soil erosion, which degrades soil structure and increases crop vulnerability to droughts. Although efforts have been deployed to measure soil erosion underneath individual centre pivots, a large-scale systematic assessment of extent and severity of soil erosion in centre-pivot irrigated fields is currently lacking. Here we used Google Earth™ satellite images to provide first evidence of widespread, severe soil erosion in centre-pivot irrigated agricultural land. We focused on the municipality of Cristalina (6154 km), in the Brazilian Central Highlands, where centre pivots irrigate approximately 60,000 ha of cropland. The study area is in the Cerrado biome, which is one of the most important grain-producing regions in the world and Brazil's main centre-pivot irrigation area. By mapping erosion features under centre pivots, we found that 29 % of centre-pivot fields displayed signs of rill erosion, with individual rills up to a length of 1200 m. Most erosion features were identified during the dry season of the Brazilian Cerrado, which coincided with the period of greater satellite-image availability. Moreover, we found that compacted centre-pivot-wheel tracks often triggered rill incision and that eroding centre-pivot fields displayed higher slope gradients and were better connected to surface waters than the non-eroding fields. Ultimately, the frequent identification of severe erosion features in the centre-pivot fields during the dry season indicates that irrigation causes and/or aggravates soil erosion in Cristalina and likely in other parts of the Brazilian Cerrado. This first systematic evidence of widespread soil erosion underneath centre-pivot systems highlights that irrigation erosion is an important but neglected driver of land degradation, and that urgent action is required to protect affected soils for future generations.
中心枢轴系统广泛用于农业灌溉。然而，低压中心枢轴系统下过度的灌溉用水量可能导致土壤侵蚀，从而破坏土壤结构并增加作物对干旱的脆弱性。尽管已经做出努力来测量单个中心枢轴下的土壤侵蚀，但目前缺乏对中心枢轴灌溉农田土壤侵蚀程度和严重程度的大规模系统评估。在这里，我们使用 Google Earth™卫星图像首次提供了广泛存在的、严重的中心枢轴灌溉农田土壤侵蚀的证据。我们专注于巴西中高原克里斯蒂纳市（6154 平方公里），那里的中心枢轴灌溉大约 6 万公顷的耕地。研究区域位于塞拉多生物群落，这是世界上最重要的粮食生产区之一，也是巴西主要的中心枢轴灌溉区。通过绘制中心枢轴下的侵蚀特征，我们发现 29%的中心枢轴农田显示出细沟侵蚀的迹象，个别细沟长达 1200 米。大多数侵蚀特征是在巴西塞拉多的旱季期间识别出来的，此时正好是卫星图像可用性更高的时期。此外，我们发现压实的中心枢轴轮迹经常引发细沟侵蚀，而侵蚀的中心枢轴农田的坡度梯度比非侵蚀农田更高，并且与地表水的连接更好。最终，旱季期间在中心枢轴农田频繁识别出严重的侵蚀特征表明，灌溉在克里斯蒂纳市乃至巴西塞拉多的其他地区引发和/或加剧了土壤侵蚀。这是首次系统地证明中心枢轴系统下广泛存在土壤侵蚀的证据，突出表明灌溉侵蚀是土地退化的一个重要但被忽视的驱动因素，需要采取紧急行动来保护受影响的土壤，以造福子孙后代。
