Effect of cropping and fertilization manners on nitrogen loss from sloping land in Yunnan.

By on-site observation and measurements of nitrogen(N)loss on a 14.6° slopping land at Gaocang Village of Fumin County in Yunnan Province from 2004 to 2006,the effects of cropping and fertilization manners on N loss were investigated.The results showed that,in the treatment of integrated hedgerows and balanced fertilizers with contour cropping,the amount of N up-taken by corn accounted for 99.42% of the total N loss from the soil,N loss by soil erosion accounted for 0.48% and N loss by runoff was 0.10%;in treatment of farmers practice of no hedgerows,local fertilizer practice and down slope corn cropping,79.36% of the total N loss from the soil was taken up by corns,20.22% lost in soil erosion and 0.42% lost in runoff.N loss by corn uptake was in treatment with down slope cropping + balanced fertilization 86% more.than in treatment with contour cropping +balanced fertilization,but N loss by soil erosion was 74.30% and by runoff was 29.31% less.Under contour cropping +balanced fertilization,adding treatment with contour hedgerow strip reduced 3.32% N loss by corn uptake and reduced N loss 86.61% by soil erosion and 56.10% by runoff;under down slope cropping + farmers fertilization,adding treatment with contour hedgerow strip reduced 4.48% N loss by corn uptake and reduced N loss 96.51% by soil erosion and 60.94% by runoff.In treatment with down slope cropping system,treatment with balanced fertilization system increased 41.28% of N loss by corn uptake,but reduced N loss 19.38% by soil erosion and 9.38% by runoff,compared with treatment with local farmers fertilization system.