Four groups of agro-forestry intercropping trials were carried out in Anhui Province. Results showed that nitrogen and phosphorus loss in runoff was significantly reduced by contour cultivation of sweet potato and cotton as compared with longitudinal cultivation. The contents of nitrogen and phosphorus in runoff were 10. 481and 0. 122 mg/ L in contour cultivation of sweet potato

while they were 43. 112 and 0. 285 mg/ L in downslope cultivation

respectively.The contents of nitrogen and phosphorus in runoff were 3. 779 and 0. 109 mg/ L in contour cultivation of cotton

while they were 38. 980 and 0. 288 mg/ L in downslope cultivation

respectively. Ditches not only intercepted runoff and sediment

but also reduced the losses of nitrogen and phosphorus carried by water and sediment. In observation period

ditches intercepted the loss of nitrogen ( 575. 09

631. 18

199. 45

and 710. 05 mg in 1 to 4 plots) and the loss of phosphorus ( 54. 54

21. 42

23. 24

and 30. 13 mg in 1 to 4 plots) in runoff. Ditches also intercepted the loss of nitrogen ( 3. 00

2. 95

1. 07

and 3. 35g in 1 to 4 plot s) and the loss of phosphorus ( 0. 80

0. 67

0. 21

and 0. 69 g in 1 to 4 plots) in sediment . Sweet potato-poplar-cotton-poplar intercropping not only significantly reduced soil and water loss

but also reduced the amount of nitrogen and phosphorus loss. The losses of water and soil in sweet potato-poplar-cotton-poplar inter cropping were 2623 and 17. 31 g / m2

while in single sweet potato-growing

they were 3138 and 19. 76 g/ m2 and in single cotton-growing

2658 and 17. 87 g/ m2

respectively. In sw eet potato and cot ton

the av erag ed losses of nit rog en and phosphorus in runoff were 17. 88 and 0. 25 mg / m2

while in sediment

21. 30 and 5. 24 mg/ m2

respectively. In sweet potato-poplar-cotton-poplar inter cropping

losses of nit rog en and phosphorus in runof f w ere 14. 23 and 0. 22 mg / m2

and in sediment

20. 08 and 4. 85 mg/ m2

respect ively. Agro-forestry production and eco-ditch measure have important roles in preserving water

soil

and nutrient and control ling agricultural non-point source pollution.