Soil Nutrient Effects on Suction and Volumetric Water Content in Heavily Compacted Vegetated Soil

Previous studies demonstrated that soil nutrients help plant growth and enhance the stability of bio-engineered slopes through plant-induced soil suction. Therefore, soil nutrient effects on the variations of suction and volumetric water content (VWC) in heavily compacted soil during evapotranspiration need to be studied. In this study, three replicates of Schefflera heptaphylla (Ivy tree) were grown for 6 months in nutrient poor and nutrient supplied compacted soil. Soil suction and VWC changes during drying of vegetated soils were measured after 3 and 6 months of plants growth. After the 3^rd and 6^th month of drying, suction increased by 5–10 kPa and 15–40 kPa, respectively in nutrient supplied vegetated soil compared to the nutrient poor soil due to increase in leaf area index (LAI) and root area index (RAI). In contrast, soil VWC was higher in all the vegetated soils after drying on the 6^th month compared to the VWC after drying on the 3^rd month. This might be due to soil-pore structure changes via bio-chemical root activities and organic matters.