Agricultural non-point source(NPS) pollution,a major factor of the upward trend in the spread of eutrophication of rivers and lakes,has become a pressing environmental concern in many regions of China as well as of the world.NPS pollutants discharged from agricultural land usually have no defined or identifiable point of outfall and enter the aquatic environment system in small quantities at a large number of points.It is therefore extremely difficult to control them by technical measures.Mitigating water q...