To reveal the effects of soil surface roughness on sheet erosion

the changes of soil surface roughness on purple soils were studied during the whole growing stages of maize based on field artificial rainfall experiments

and the effects of soil surface roughness on runoff and sediment yield of sheet erosion process were analyzed. The results showed the soil surface roughness presented an increasing-first-and-then-decreasing trend with the advance of maize growing period under the rainfall intensity of 1.0 mm/min

and the maximum of increasing range appeared in maize seedling stage and the maximum of decreasing range appeared in mature stage. Under the rainfall intensity of 1.5 and 2.0 mm/min

the soil surface roughness presented a decreasing-first-and-then-increasing trend with the advance of maize growing period

and the changing range of soil surface roughness was the?greatest at the stage of maize seedling - jointing. Under the rainfall intensity of 1.0 mm/min

the changes of soil surface roughness presented a decreasing-first-and-then-increasing -and -decreasing trend

and these changeswere consistent with the changes of surface runoff under the rainfall intensity of 1.0 mm/min. At the stages of maize seedling-jointing and jointing-tasseling

the changes of soil surface roughness were consistent with the changes of surface runoff under the rainfall intensity of 1.5 and 2.0 mm/min

but inconsistent with the changes of surface runoff at the stage of maize tasseling- mature. At the stages of maize seedling and jointing

the changes of soil surface roughness showed the consistency with the changes of sediment yield intensity

however

they presented the opposite?changes in soil surface roughness and sediment yield intensity at the stages of maize tasseling and mature. In maize jointing stage

there was a very?significant negative relationship between the changing range of soil surface roughness and runoff amount

but a positive relationship between both in maize tasseling stage. In maize seedling

jointing and mature stage

there were the significant or very?significant positive relationships between the changed range of soil surface roughness and sediment yield amount

however

a very significant negative relationship in maize tasseling stage. These results would provide theory basis for posing the sheet erosion nature of soil surface roughness

and also serve for harnessing soil and water loss of the slope farmland.