Water repellency of soil in different types of rubber-based agroforestry ecosystems in Xishuangbanna

Water drop penetration time and water repellency index used to determine the soil water repellency and soil physicochemical properties were tested in four rubber-based (Hevea brasiliensis) agroforestry ecosystems with different interplants (Camellia sinensis,Theobroma cacao,Flemingia macrophylla,and Dracaena americana) and rubber monoculture in Xishuangbanna,Southwest China.The relationship between soil properties and soil water repellency was determined by Pearson correlation analysis and stepwise regression analysis.The results showed that both the persistent of soil water repellency time and the index of soil water repellency in rubber monoculture were significantly higher than agroforestry ecosystem.Different land use patterns have certain influence on the hydraulic characteristics of the soil,except Flemingia macrophylla,the soil saturated hydraulic conductivity in rubber monoculture was significantly lower than that in rubber-based agroforestry ecosystems(P<0.05).Pearson correlation analysis showed that there was a significant negative relation between soil water repellency and soil saturated hydraulic conductivity (P<0.05,r=-0.556).Stepwise regression analysis showed that the soil bulk density and soil texture were the most significant factors in controlling soil water repellency in the rubber-based agroforestry ecosystems. The results indicated that conversion rubber monoculture to rubber-based agroforestry ecosystem can effectively reduce soil water repellency and increase soil water infiltration, and ultimately control soil erosion.