ABSTRACT
Laboratory studies of detachment of soil particles from a sandy soil by raindrop impact in storms of 50 mm/h and 61 mm/h for 5 min duration showed that the rate of detachment under Brussels sprouts decreased as the canopy cover increased from 0 to 15–25 percent but then increased again with further increases in percentage canopy cover. With 50 percent cover, the detachment rate equalled that on bare soil. Data for potatoes showed some support for a similar trend but those for sugar beet were less conclusive. Measurements of erosion on the same soil under a cover of 180 mm tall toy plastic oak trees in a 21-min three-stage storm of rainfall followed by rainfall with additional runoff and runoff without rainfall showed that a 15 percent canopy cover decreased erosion by 50 percent compared with that on bare soil. Erosion rates increased again, however, with further increases in canopy cover. The major difference in soil loss with different canopy percentages occurred in the first stage of the storm and was attributed to differences in soil detachment by raindrop impact. The results lend further support to a small but increasing body of literature which shows that under certain circumstances plant covers are associated with higher rather than lower rates of erosion. The reasons for this and the circumstances involved remain imperfectly understood.
