Increasingly aggravated non-point source pollution resulting from intensified farming activities has drawn wide concerns from the society. Among the farming activities, overdose of chemical fertilizers has been blamed the most. Sichuan Basin is one of major grain production basis in China where farming on sloping lands is prevailing and intensive with increased fertilizer use. This has put great pressure on the widespread water eutrophication, particularly in the summer when heavy rains usually cause serious soil loss and water runoff that carry away large amounts of nutrients from the farmlands. Previous studies have well addressed the patterns of soil erosion and surface runoff with which how and how much soil nutrients are lost from the sloping lands, however, there is still lack of research on effects of surface mulching with crop straw or plastic film on soil nutrient losses through soil erosion and water runoff. Therefore, the objectives of this field study were to investigate effects of different cultivation and mulching methods on different types and amounts of soil erosion, pathways and amounts of nutrient losses during corn growing season from a purple soil located on a sloping landscape in the Sichuan basin. The experiment was carried out with a randomized block design consisting of nine treatments and three replications. There nine treatments included (1) conventional down slope ridge cultivation, (2) flat cultivation (non-ridged), (3) contour ridge cultivation, (4) contour alley cropping, (5) down slope ridge cultivation + straw mulching, (6) flat cultivation + straw mulching, (7) contour ridge cultivation + straw mulching, (8) down slope ridge cultivation + plastic film mulching, and (9) contour ridge cultivation + plastic film mulching. The results indicated that the effect of straw mulching on reducing soil and water losses and on improving corn yield was superior to the use of plastic film. The straw mulching significantly reduced surface runoff by 73.9% -86.2% in spite of the increase in underground runoff by 15.4%-156.4%, resulting in reduction of total runoff by 32.5%-66.6% and soil erosion by 96.4%-98.1%. Though use of plastic film alleviated the underground runoff and total runoff to some extent, the difference was not significant compared to the traditional cultivation. Amount of N lost from the soil was 37.4 kg/hm2, of which N losses through underground runoff accounted for 70.1%. The straw mulching decreased total N losses by 12.8%-65.1% in spite of some increase in N loss through underground runoff. Amount of P lost from the soil was relatively small (9.32 kg/hm2) but it was mainly moved out of the field with sediments, accounting for 92.1% of total P losses. Amount of K lost from the soil reached 183.3 kg/hm2 of which the loss through sediments that were the main carrier of K account for 96.5%. Mulching soil surface with either straw or plastic film effectively controlled P and K losses. Compared to the traditional, down slope ridge cultivation, the contour ridge cultivation produced higher corn yields while it lowered nutrient, soil and water losses associated with surface and underground runoff and soil erosion. The integration of flat cultivation and straw mulching can be an improved practice as it does realize straw recycling, improve crop yields and reduce losses of soil and water and plant nutrients.