Background The main causes of soil and water loss of sloping farmland in northeast black soil region are the concentration of rainfall and low vegetation coverage on gentle and long slopes of sloping farmland. Therefore, it is an important measure to protect soil and water by effectively preventing and controlling sediment production on slope surface. In this paper, Liangshigou watershed in Keshan county, Heilongjiang province, located in the core area of black soil, was selected as the research object. Under the condition of natural rainfall, we studied the images of runoff and sediment yield of different slope farmland by different water conservation measures, aiming to provide reference for the management of slope farmland in this region.

Methods Method of runoff plot was used, i.e., in 3°, 5°, and 8° slope respectively, a total of 18 runoff plots with soil and water conservation measures of slope, contour tillage, ridge plant zone, horizontal terrace, ridge tillage, and bare land were set up. While runoff generated after rain, steel ruler was used to measure the water depths inside the branch barrel and collecting barrel, the runoff was calculated, sediment mixture samples were taken from sampling bottles, then were filtered, dried, weighed indoor, and finally sediment concentration was calculated.

Results 1) The reduction rates of runoff under 3°slope contour tillage were 95.34% and 96.35%, respectively, compared with ridge tillage and bare land. Soil loss decreased by 95.49% and 97.42, respectively. 2) Compared with ridge tillage and bare land, the reduction rate of runoff by plant belt measures on 5° slope land was 86.74% and 89.49%, respectively. Soil loss decreased by 93.04% and 96.34%, respectively. 3) The reduction rates of runoff in 8° slope horizontal terraces were 55.63% and 72.57%, respectively, compared with ridge tillage and bare land. Soil loss decreased by 47.71% and 85.00%, respectively. Compared with bare land, the runoff reduction rates of 3°, 5° and 8° ridge plots were 18.3%, 21.7% and 38.2%, respectively.

Conculsions It shows that under natural rainfall conditions, the arrangement of soil and water conservation measures such as contour tillage, ridge plant belt and horizontal terraced field significantly reduced the times of runoff and volume of runoff. It provides foundation support for slope farmland management in northeast black soil region.