INTERACTION BETWEEN PLANT ROOTS AND SOIL WATER FLOW IN RESPONSE TO PREFERENTIAL FLOW PATHS IN NORTHERN CHINA

Preferential flow is expected to provide preferential channels for plant root growth and variations in soil water flow, but few studies were conducted to imply the impacts of these changes, particularly for preferential flow in stony soils. This study aimed to characterize soil water flow and plant root distribution in response to preferential flow paths and quantitatively describe the relation between plant root distribution and soil water flow. Field dye-tracing experiments centered on experimental plants were conducted to determine the root length density and soil water flow process. Laboratory analyses were performed to characterize changes in the relative concentration of the accumulated effluent and the degree of interaction between plant roots and soil water flow. The amount of fine plant roots with preferential flow paths decreased with increasing soil depth for all experimental plots. The largest plant roots were recorded in the upper soil layers to a depth of 20cm. The relative concentration of the accumulated effluent increased with time and decreased with soil depth under saturated soil conditions, whereas a distinct early turning point for the relative concentration of the accumulated effluent was observed in the 0-20-cm soil columns, and the relative concentration of the accumulated effluent initially decreased and then increased with time under unsaturated soil conditions. This study provides quantitative information with which to characterize the interaction between plant roots and soil water flow in response to preferential flow paths in soil-plant-water systems. Copyright (C) 2016 John Wiley & Sons, Ltd.