Water quality in the agriculturally dominated (60-80%) Choptank Basin has been degrading due to anthropogenic inputs of N and P. The Choptank is a tributary to the Chesapeake Bay, and the EPA Chesapeake Bay Program has adopted the application of agricultural and residential Best Management Practices (BMPs) to reduce export of N, P and TSS to estuarine waters. We have been monitoring 15 subwatersheds in the Choptank basin for chemistry (NO3, NH4, PO4, TN, TP and TSS) and discharge from 2003-present. Of these, we chose 4 of similar land use and size (8-14km2) to intensely monitor starting in fall 2013. There is 1 control and 3 experimental watersheds, where we began promoting increased BMP adoption starting in 2014. Our study is testing the hypothesis that through the collective actions of farmers and residents applying more BMPs to their land; there will be sediment and nutrient reductions observable on farm fields (field scale), throughout the watersheds (meso scale), and/or at the watershed outlet (watershed scale). We have been and continue to conduct monthly baseflow sampling at all 3 scales and we are sampling storms 8-10 times per year at the watershed scale.
Results/Conclusions
After 4.5 years we have completed 2 years of baseline and 2.5 years of post-BMP implementation monitoring at all three scales. After year 1 opinion surveys of farmers, we learned that the main impediments to BMP adoption were financial costs and the time involved. Therefore, we sought additional funding sources to alleviate this impediment and we were able to implement 35 new BMP’s in the experimental watersheds including flying cover crops on 2,189 acres out of a possible 4,906 cropland acres (45 %). Throughout our study, we have seen decreased N at several meso and field scale sites (48 -60 % reduction) where additional BMP’s have been installed. We have also measured reductions (24 -35 %) of N in 2 of the 3 experimental watershed outlets possibly due to enhanced BMP adoption during our study period. Consecutive years of cover crops on soybeans and lima beans appear to be one of our most influential BMP’s and this approach is not commonly utilized by our farmers to date. Through various forms of recruitment we were able to get 64% of farmers to work with us but only 3% of residents.