Submitted to: The Science and Management of Soil and Water: Lake Champlain
Publication Type: Book / Chapter
Publication Acceptance Date: 12/20/2002
Publication Date: 3/20/2004
Citation: Jokela, W.E., Clausen, J.C., Meals, D.W., Sharpley, A.N. 2004. Effectiveness of agricultural best management practices in reducing phosphorus loading to Lake Champlain. The Science and Management of Soil and Water: Lake Champlain. 14 p. Interpretive Summary: Inputs of P are essential for profitable crop and livestock agriculture. However, its export in watershed runoff can accelerate the eutrophication of receiving fresh waters. Eutrophication has been blamed for the decline in water quality in the freshwater Lake Champlain over the past three decades. Increased P loading to surface waters has come from a range of point sources and both urban and agricultural nonpoint sources. Recent estimates for Lake Champlain indicate that 30% of the P comes from point sources, primarily sewage treatment plants, and 70% from nonpoint sources in the Vermont-New York watershed. Recent estimates suggest agriculture contributes as much as 90% of the nonpoint P. This paper reviews the current situation regarding the management of P in agriculture in the Lake Champlain watershed. It is concluded that to minimize P losses and decrease the incidence and severity of eutrophication, a comprehensive management strategy is needed that combines effective, focused implementation of conservation measures at the field, farm, and watershed level and long-term efforts to achieve a more balanced whole-farm P budget.
Technical Abstract: Phosphorus is an essential element for the growth of terrestrial and aquatic plants. But in P-limited freshwater lakes, increased P loading can accelerate eutrophication and an associated growth of undesirable algae and aquatic weeds. Eutrophication has been blamed for the decline in water quality in freshwater lakes and estuaries in the Northeast over the past decades. The role of excessive P levels in water quality degradation in Lake Champlain is well documented, with P concentrations in parts of Lake Champlain (Missisquoi and St. Albans Bays and the South Lake, in particular) highly eutrophic. Increased P loading to Lake Champlain has come from a range of point sources (30%) as well as urban and agricultural nonpoint sources (70%). Agriculture is believed to contribute over 90% of the nonpoint P. Lake Champlain is especially sensitive to nutrient inputs from the watershed because the land to water area ratio (19:1) is higher than that of many other lake watersheds. Implementation of BMPs that reduce erosion and runoff or limit loss of P from a field can lead to improved water quality in some situations; but in the long term such improvements will be limited unless whole-farm P budgets are brought into closer balance. What is needed is a comprehensive approach that combines effective, focused implementation of BMPs at the field, farm, and watershed scale and more long-term efforts to achieve a more balanced whole farm P budget.