Soil Erosion and Degradation Research Group, Department of Geography, Valencia University, Blasco Ibàñez, 28, 46010 Valencia, Spain.
Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
Sci Total Environ. 2021 Sep 15;787:147549. doi: 10.1016/j.scitotenv.2021.147549. Epub 2021 May 7.
Agriculture is known to commonly cause soil degradation. In the Mediterranean, soil erosion is widespread due to the millennia-old farming, and new drip-irrigated plantations on slopes, such as the citrus ones, accelerate the process of soil degradation. Until now, the published data about soil erosion in citrus orchards is based on short-term measurements. Long-term soil erosion measurements are needed to assess the sustainability of drip-irrigated citrus production and to design new strategies to control high soil erosion rates. The objective of this study is to assess long-term soil erosion rates in citrus plantations and report the changes in soil bulk density as indicators of land degradation. We applied ISUM (Improved Stock-Unearthing Method) to 67 paired trees in an inter-row of 134 m (802 m plot) with 4080 measurements to determine the changes in soil topography from the plantation (2007) till 2020. Soil core samples (469) were collected (0-6 cm depth) to determine the soil bulk density at the time of plantation (2007) and in 2020. The results demonstrate an increase in soil bulk density from 1.05 g cm to 1.33 g cm. Changes in soil bulk density were higher in the center of the row as a result of compaction due to passing machinery. Soil erosion was calculated to be 180 Mg ha y due to a mean soil lowering of 1.5 cm yearly. The highest soil losses were found in the center of the inter-row and the lowest underneath the trees. The extreme soil erosion rates measured in new drip-irrigated citrus plantations are due to soil lowering in the center of the inter-row and in the lower inter-row position where the incision reached 80 cm in 13 years. The whole field showed a lowering of the soil topography due to extreme soil erosion and no net sedimentation within the plantation. The results show the urgent need for soil erosion control strategies to avoid soil degradation, loss of crop production, and damages to off-site infrastructures.
农业通常会导致土壤退化。在地中海地区，由于数千年的农业耕作，土壤侵蚀现象普遍存在，而新的滴灌种植园（如柑橘园）在斜坡上的种植则加速了土壤退化的进程。到目前为止，关于柑橘园土壤侵蚀的已有数据是基于短期测量得出的。需要进行长期的土壤侵蚀测量，以评估滴灌柑橘生产的可持续性，并设计新的策略来控制高土壤侵蚀率。本研究的目的是评估柑橘种植园中土壤的长期侵蚀速率，并报告土壤容重的变化，作为土地退化的指标。我们采用 ISUM（改进的破土暴露法）对 134 米行距（802 米小区）的 67 对行间树进行了测量，以确定从种植园（2007 年）到 2020 年种植园土壤地形的变化。共采集了 469 个土壤芯样（0-6 厘米深度），以确定种植园时期（2007 年）和 2020 年的土壤容重。结果表明，土壤容重从 1.05 克/立方厘米增加到 1.33 克/立方厘米。由于机器通过导致的压实，行间中心的土壤容重变化较大。由于每年平均土壤下降 1.5 厘米，计算得出土壤侵蚀量为 180 Mg ha y。在行间中心和树下位置的土壤侵蚀量最大，而在行间中心和较低的行间位置的土壤侵蚀量最小。新的滴灌柑橘种植园中测量到的极端土壤侵蚀率是由于行间中心和切沟深度达到 80 厘米的较低行间位置的土壤下降所致，13 年内土壤下降了 80 厘米。整个场地由于极端土壤侵蚀导致土壤地形降低，而种植园内没有净沉积。结果表明，迫切需要采取土壤侵蚀控制策略，以避免土壤退化、作物减产和场外基础设施受损。
