重庆市农田氮磷流失系数初探

An Exploration of Farmland Nitrogen and Phosphorus Loss Coefficient in Chongqing City, China

结合重庆市农业生产的实际情况，在全市设置监测点12个，以一个种植季为监测周期，采集每次降雨后产生的径流和淋溶水，测定其产生量和氮、磷浓度，测算出氮磷流失系数。结果表明，氮主要以地下淋溶途径流失进入水体，磷主要是以地表径流途径流失进入水体。各监测点总氮流失系数在0．011％-10．82％之间，总磷流失系数在0．013％-0．894％之间。氮的流失以硝态氮为主。最高占总氮流失的61．214％。从地表径流看，氮磷流失系数与地面坡度、施肥量成正相关，坡度越高、施肥量越大，氮磷流失系数就越大。从地下淋溶看，养分流失主要受土壤性质的影响，砂质土壤在灌溉或者降雨后，更容易造成养分的流失。

Considering the actual situation of agricuhural production of Chongqing City, 12 monitoring sites were established in the munici- pality, with a planting season as a monitoring cycle. Rainfall runoff and leaching water were collected to determine the yield and nitrogen phosphorus concentration, as well as nitrogen and phosphorus loss coefficient. The results showed that nitrogen entered the water body mainly though underground leaching, and phosphorus was drained predominantly with surface runoff. Total nitrogen loss coefficient was between 0.011% and 10.82%, total phosphorus loss coefficient was between 0.013% and 0.894%. Nitrogen loss was mainly with nitrate nitrogen, ac- counting for 61.214% of the total nitrogen loss. Based on the surface runoff, nitrogen and phosphorus loss coefficient was closely related to the ground slope and fertilizer loading rate. Higher coefficients of nitrogen and phosphorus losses were associated with steeper surface slope, and the heavier fertilizer usage. As of underground leaching wate, nutrient losses were mainly affected by soil properties. Irrigation or rainfall was more likely to cause the loss of nutrients in sandy soil.