Surface mulch and ground vegetation have been commonly implemented to prevent soil erosion and to control soil loss. Both practices have also been considered in most process-based simulation models, in which the amount of canopy cover and biomass were incorporated into models to reflect their contribution to erosion control. However, infiltration processes under protection of neither practice has received equal attention. Therefore, straw-mat and Carpet grass were installed as surface treatments and bare fallow plot was chosen as the control on runoff plots respectively.
Soil moisture at 5, 15, and 30 cm below ground surface was monitored continuously and separately using EC-5 soil moisture sensors. Rain gauge with 0.2-mm resolution, which attached to a data logger was used to document the rainfall events. The study period covered the entire rain season in 2016, during which straw-mat was replaced entirely once.
Time-to-peak of soil moisture as well as peak soil moisture content were found to be related to storm duration and accumulative precipitation. Data logged on site indicated that time-to-peak at all monitoring depths under Carpet grass tended to delay as compared to that from straw-mat treatment. In addition, time-to-peak and peak soil moisture content were reset after the replacement of fresh straw-mat, which was mainly due to replenishment of straw-mat’s water holding capacity. Bare control plot demonstrated the longest lag in time-to-peak and the lowest soil moisture content at all depths due to progressive surface seal that induced by raindrop impact. The unique responses of infiltration under different surface treatments may require attention in future modeling.