关键词: 坡耕地, 地表径流, 泥沙, 养分流失

Abstract: Transport of nitrogen and phosphorus from sloping crop fields to waterbody causes eutrophication and non-point source pollution of the waterbody.A two-year(2005-2006) field experiment was conducted to study characteristics of nutrient loss from sloping fields in the Miyun Reservior watershed.The fields were managed in the same way as the local farmers do.Results of the experiment show that 1) the amounts of runoff and sediments therein from the sloping fields increased with the gradient of slope after rainfall,demonstrating a linear correlation;2) slope gradient did not show much effect on nutrient content of both runoff and sediments,but much on amount of nutrient lost with sediments;3) more nutrient lost with sediments than with runoff,and the proportion of nutrient lost with sediments versus total nutrient loss increased with slope gradient;4) the N,P lost from sloping fields were mainly originated from the chemical fertilizers applied by farmers;5) to control non-point source pollution and protect water quality of the water source,it is especially urgent to readjust the agricultural structure of the region,rebuild crop fields to intercept or reduce soil loss and control input of chemical fertilizers.

Key words: sloping field, runoff, sediment, nutrient loss