The effect of crop covers on rainfall characteristics and splash detachment

Abstract

A laboratory study is presented in which the effects of increasing canopy cover on rainfall characteristics and splash detachment under crops were investigated. Data were collected using a simulated rainfall of 61 mm/h for 5 min duration typical of an erosive storm in the Silsoe area, and a local erodible sandy soil of the Cottenham series. Experiments were carried out for three locally-grown crops; Brussels sprouts, sugar beet and potatoes. Measurements were made of the percentages of the storm rainfall reaching the ground surface as throughfall, leaf drips and stemflow. Soil detachment, rainfall energy and rainfall intensity were determined at three discrete positions under the plants, under the canopy, below the canopy margin and beneath the leaf drips. As the plant grows, it is shown that the percentage interception area increases, the volume of throughfall decreases and the volumes of stemflow and leaf drips increase. Soil detachment is reduced except at the leaf drip points under Brussels sprouts and sugar beet where it increases. Although the kinetic energy of the rainfall under the plants in all three positions is less than that of the control storm, it increases as canopy area increases. This results in a negative relationship between soil detachment and kinetic energy, a trend reported in previous work but still not fully explained.