Abstract
Crop–hedgerow intercropping systems are important agroforestry systems for preventing soil degradation and soil nutrient losses on sloping cultivated land in the Three Gorges Reservoir (TGR) area of China. However, the mechanism by which hedgerow spatial layouts and the planting patterns affect soil nutrients and crop yields is still uncertain. A two-year field experiment was performed on a 10° slope to investigate the effects of slope position and different crop–hedgerow intercropping systems on soil physicochemical properties and crop yields. The treatments were a two-belt mulberry contour hedgerow (TM), a two-belt compound mulberry–vetiver hedgerow (TCMV), a two-belt compound mulberry–alfalfa hedgerow (TCMA), a seven-year-old two-belt mulberry contour hedgerow (7YTM), a seven-year-old mulberry border hedgerow (7YBM), a seven-year-old pure mulberry (7YPM), and a control treatment (CT, no hedgerows). In all treatments, except 7YPM, there was a significant (p < 0.05) increase in crop yield, clay content, soil total nitrogen (STN), acid-hydrolyzable nitrogen (AHN), and soil organic carbon (SOC) with declining slope position, whereas soil bulk density (BD), sand content, and soil pH showed the opposite trend. In TM, TCMV, TCMA, and 7YTM, the mustard yields and soil properties were better than those in CT, and there was no significant (p > 0.05) difference in mustard yield or soil properties between the upper-middle and lower-middle slope positions. Compared with CT, TCMV, and TCMA increased mustard yields by 8.28% and 9.86%, respectively, while 7YTM, 7YBM, and 7YPM reduced mustard yields by 7.69%, 17.69%, and 29.73%, respectively. TCMV and TCMA were confirmed to be viable intercropping systems for significantly reducing nutrient losses, improving soil quality, and changing soil nutrient distributions to maintain optimum crop yields on sloping lands.
Highlights
The degradation of sloping agricultural lands and nutrient losses arising from soil erosion, excessive fertilizer use, environmental pollution, and unreasonable farming systems are two of the most severe environmental issues currently being confronted in numerous countries worldwide [1,2,3,4]
The two-belt compound mulberry–vetiver hedgerow (TCMV) and two-belt compound mulberry–alfalfa hedgerow (TCMA) systems had the highest crop yields and the greatest ability to reduce the spatial variability of the soil physicochemical properties
These results indicate that the ability of compound contour hedgerows to retain runoff, eroded sediments, and nutrients could be a major factor in maintaining the beneficial physicochemical properties of soil
Summary
The degradation of sloping agricultural lands and nutrient losses arising from soil erosion, excessive fertilizer use, environmental pollution, and unreasonable farming systems are two of the most severe environmental issues currently being confronted in numerous countries worldwide [1,2,3,4]. The soil erosion by water has been recognized as the main form of soil degradation in sloping agricultural lands and has a series of adverse effects, such as soil fertility reduction, soil organic matter loss, land productivity reduction, and water body pollution [5,6,7,8]. Soil degradation caused by soil erosion is inevitable, especially in the sloping farmlands of southwestern China, where high-energy rainstorms frequently occur [9,10,11]. Understanding the spatial heterogeneity of soil physicochemical properties is essential for determining best practices for soil management, especially in the hilly areas of southwestern
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