Study on soil improvement function of hedgerows in slope farmland in Three Gorges Reservoir Area | 三峡库区坡耕地植物篱土壤改良作用研究

Chinese. 从土壤改良指标中找出差异明显、对植物篱土壤改良作用研究贡献大的指标，为以后植物篱土壤改良研究中指标的选取提供参考，并筛选出适宜于长江三峡库区坡耕地、土壤改良作用较好的植物篱模式。从土壤肥力、土壤物理性质、根系状况和水土保持特性4个方面，选取15个指标作为土壤改良作用指标，根据信息熵理论确定每个指标的重要性，利用熵权决策法计算6种植物篱模式（柑橘、沙梨、花椒、黄荆、桑树、紫背天葵）与理想植物篱模式的贴近度，比较其土壤改良作用的大小。研究不同植物篱模式的土壤改良效果时，可考虑选择熵权大的指标来进行比较；15个土壤改良指标中，饱和导水率的熵权最大，为0.123，其次是水解氮（0.097）和土壤中0.25 mm水稳性团聚体的含量（0.091），阳离子交换量的熵权最小，为0.046。以贴近度为指标进行比较，6种植物篱模式的土壤改良作用大小为黄荆类（0.652）沙梨类（0.690）柑橘类（0.769）桑树类（0.778）紫背天葵类（0.782）花椒类（0.817）。15个土壤改良指标中，反映土壤物理性质的指标对比较不同植物篱模式土壤改良作用大小的贡献较大；黄荆枝叶茂盛，根性发达，土壤改良作用最好，通过熵权决策法得出的结果与实际相符。

English. The study was to find significant indicators affecting hedgerows and to select hedgerows suitable in the slope farmland of Three Gorges Reservoir Area. Information entropy theory was applied to define the importance of every index based on calculating fifteen index values which reflected soil physical properties, soil fertility, root system and soil and water conservation properties, and entropy weight decision-making method was used to study the difference in soil improvement function of six hedgerow intercropping systems by comparing the closing degree of each hedgerow to ideal hedgerow. The study on the difference of soil improvement function about various hedgerows can take the indicators with big entropy weight. Among the fifteen indexes, the saturated hydraulic conductivity had the largest entropy weight which was 0.123, followed by available nitrogen (0.097) and 0.25 mm soil water stable aggregate content (0.091), while the cation exchange capacity, 0.046 was the smallest one. The soil improvement function of Vitex negundo (0.652) hedgerow was superior to the other five kinds, followed by Pyrus pyrifolia (0.690), Citrus reticulate (0.769), Morus alba (0.778), Begonia fimbristipula (0.782) and Zanthoxylum bungeanum (0.817). The indexes of soil physical properties are more important in comparing soil improvement function of different hedgerows than the other eleven indexes. As V. negundo is thick in leaves and branches, and has well developed root system, its soil improvement function is the highest one among the six hedgerows. The results are in line with the actual facts.