| Soil erosion and rocky desertification in karst areas are prominent ecological and environmental problems in southwest China,which restrict the development of regional economy and society.Mixed agroforestry planting measures in karst areas with soil erosion control on sloping land as the core are an important way to achieve ecological restoration and winwin economic benefits.It is of great theoretical and practical significance to carry out research on soil hydrology effects of different mixed agroforestry planting patterns in karst slopes and to screen suitable compound planting patterns for soil erosion control in karst slopes and sustainable development of the region.In this study,the cultivated land of typical karst slope in northwest Guizhou was taken as the research object,and in-situ observation of field runoff plot and laboratory experiment were combined.In the different agroforestry planting measures in the studied area（loquat + soybean,pomegranate,hot pepper,plum and perennial ryegrass + eggplant + peanut,walnut,cherry,peach and maize monoculture）of soil physical and chemical properties and soil based on the analysis of hydrological characteristics,using principal component analysis（PCA）on the soil hydrological characteristics of agroforestry planting measures to carry on the comprehensive evaluation,the results show that the（1）The mixed agroforestry planting pattern has a positive effect on the improvement of soil structure.The soil bulk density increased with the increase of soil depth,and there were significant differences among the planting measures of mixed agriculture and forestry.In general,the soil bulk density was as follows: walnut + peanut < loquat + soybean < cherry+ eggplant < peach tree < plum + rye grass < pomegranate + pepper < corn,and the soil bulk density was the largest at 20 ～ 30 cm in each soil layer.The total soil porosity showed as follows: corn < plum + rrye grass < peach tree < cherry + eggplant < pomegranate + pepper < loquat + soybean loquat +soybean > walnut + peanut > pomegranate + pepper > plum + ryegrass >peach tree > corn.（3）Agroforestry measures can increase soil water infiltration,regulate soil water content and reduce surface runoff.The seasonal trend of soil water content was summer > autumn > spring > winter,and that of pomegranate + pepper > walnut + peanut > loquat + soybean > plum +ryegrass > cherry + eggplant > peach tree > corn.The field water holdup of various mixed agroforestry planting measures was maize < plum +ryegrass < cherry + eggplant < peach tree < pomegranate + pepper < loquat+ soybean < walnut + peanut.All the measures of mixed agriculture and forestry had better regulation function of surface runoff,among which the measures of walnut + peanut were the least,and the effect was better than that of corn monoculture.Agroforestry can increase soil water infiltration and adjust soil hydrological infiltration process.The initial infiltration rate varied from 1.10 to 19.82mm/min,the stable infiltration rate varied from0.53 to 9.3mm/min,and the average infiltration rate varied from 0.19 to3.30mm/min.The total infiltration within 60 min ranged from 11.42 mm to197.96 mm,and the soil permeability decreased with the increase of soil depth.The soil permeability of various agroforestry planting measures showed the following trend: walnut + peanut > cherry + eggplant > loquat+ soybean > pomegranate + pepper > peach tree > plum + ryegrass > corn.The fitting effect of the general empirical model is the best,followed by Horton model and Kostiakov model,and Philip model is the worst.The comprehensive effect of soil hydrology under mixed agroforestry cropping was in the trend of walnut + peanut > cherry + eggplant > loquat + soybean >pomegranate + pepper > peach tree > plum + ryegrass > corn,indicating that the combination of walnut + peanut had the best soil hydrology regulation function,while maize mono-cropping had the worst soil hydrology regulation function.（4）Agroforestry measures affected the soil hydrological characteristics by improving the soil physical and chemical properties.Soil hydrological characteristics were significantly correlated with soil bulk density,total porosity,capillary porosity,non-capillary porosity,soil available phosphorus,soil available potassium,and soil bulk density was significantly negatively correlated（P < 0.05）.The linear fitting model was the best.There was a significant linear correlation between the two,and the goodness of fit was 0.627.The equation was β=0.035+0.715α. |
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