Trend Analysis of Nutrient Concentrations and Loads in Surface Water in an Intensively Fertilized Watershed

摘要: Nutrient concentrations and loads from 1988 to 1997 at the surface-water outlet of a heavily fertilized watershed in Brittany region, west France, were analyzed for trends. The 1240-ha is characterized by milk production an increasing indoor pig poultry production. A nonparametric statistical analysis performed on mean monthly annual data detected no trend nitrate total P 1997. When comparing same month each year study, decreasing was November flow adjusted concentrations, October maximum concentrations. An August No loads. multiple regression showed that concentration positively correlated rainfall percent area corn (Zea mays L.). nutrient global mass balance constructed 1988, 1991, 1994 explain lack despite intensification during these years. Results this farmers have compensated increased on-farm nutrients animal manure purchasing less fertilizers; therefore, budget remained relatively stable.