Filter strips are demonstrated to substantially reduce certain constituents such as nitrate and some pesticides. They do this without occupying much more space than traditional field drainage ditches.
Filter strips apply on 1) cropland at the lower edge of fields or above conservation practices such as terraces or diversion or on fields adjacent to stream, ponds, and lakes; 2) in areas requiring waste management systems to treat polluted runoff; 3) on forestry operations.
The filter strip practice considers pollutant type, length of flow, width and depth, slopes, and vegetative species.
NRCS FOTG Code 393