Alley cropping agroforestry systems are complex agroecosystems highlighted for their positive effects on soil quality. However, the potential spatial heterogeneity of soil quality created by tree rows at the plot scale has seldom been studied. The aim of this study was to evaluate soil quality at the plot scale, under tree rows and along transects perpendicular to the tree row and to compare alley cropping systems with monocropping systems. This study was performed on an alley cropping system that combined hybrid walnut trees (21 years old) and peas. Topsoil was sampled at tree rows between 1 and 2, 2 and 4 and 4 and 6.5 m from the tree row in the alley cropping system, as well as in a neighbouring monocropping plot. Physical, chemical and microbiological indicators of soil quality were measured. Tree row implantation induced spatial heterogeneity in the chemical indicators, microbial biomass, activities and community structure at the alley cropping plot scale. Alley cropping not only improved microbiological soil quality indicators within the tree rows but also in the interrows when compared to a monocropping system. These indicators were then integrated into one soil quality index (SQI) built through a statistical approach. The soil quality index was calculated for the monocropping plot and for each position within the alley cropping plot. After 21 years of agroforestry practice, tree rows and permanent grass cover improved the SQI until 2 m in the interrow. Weighted SQIs were calculated relative to the surface area of each location for the entire alley cropping plot (i.e., tree row + interrow positions) and for the entire alley cropping interrow (i.e., removing the tree row surface area). The weighted SQI of the entire alley cropping plot significantly increased compared with that of the monocropping plot.

胡同种植农林业系统是复杂的农业生态系统，因其对土壤质量的积极影响而突出。然而，很少研究在样地尺度上由树行造成的土壤质量的潜在空间异质性。本研究的目的是评估样地尺度、树行下和沿垂直于树行的横断面的土壤质量，并将小巷种植系统与单一种植系统进行比较。这项研究是在胡同种植系统上进行的，该系统结合了杂交核桃树（21 岁）和豌豆。在距离胡同种植系统中的树行 1 和 2、2 和 4 以及 4 和 6.5 m 之间的树行以及相邻的单作小区中对表土进行采样。测量了土壤质量的物理、化学和微生物指标。树行种植在胡同种植地尺度上引起化学指标、微生物生物量、活动和群落结构的空间异质性。与单一种植系统相比，胡同种植不仅改善了树行内的微生物土壤质量指标，而且还改善了行间的微生物土壤质量指标。然后将这些指标整合到一个通过统计方法建立的土壤质量指数 (SQI) 中。计算单作小区和胡同种植小区内每个位置的土壤质量指数。经过 21 年的农林业实践，树行和永久草覆盖将 SQI 提高到了 2 m。相对于整个胡同种植区的每个位置的表面积计算加权 SQI（即，树行 + 行间位置）和整个胡同种植行间（即，去除树行表面区域）。整个胡同种植地的加权SQI较单作地显着增加。