Year Established: 2011 Start Date: 2011-03-01 End Date: 2013-02-28
Total Federal Funds: $60,008 Total Non-Federal Funds: $144,255
Principal Investigators: Arne Bomblies, Jane Hill
Abstract: Farmers in Vermont often apply manure fertilizer to their fields in the spring after April 1, when a ban on the practice expires annually. This seasonal ban is intended to reduce nonpoint phosphorus loading from the high runoff generated during spring flush events, when the ground is still frozen. However, phosphorus (P) loading to Lake Champlain remains a problem, and the practice of spreading manure on fields outside of the period of the ban (December 15th – April 1st) may still have adverse impacts on environmental quality, if hydrological conditions lead to impermeable soil due to saturation. Critical source areas of nonpoint phosphorus pollution within the Lake Champlain watershed contribute the most P to the watershed, however their identification remains a challenge. Land characteristics often vary at a sub-plot scale. Topographic variability can lead to preferential flow paths and accumulation of water, which can have a greater scouring and mobilization effect. The identification of critical source areas within the watershed remains elusive, because intra-field variability is usually ignored. We aim to investigate the role of the variability leading to plot runoff by systematically measuring the physical and chemical characteristics at a field site and then use them to populate a process-based model with distributed parameters. Mechanistic, process-based models are able to simulate the detailed causative pathways between perturbations and system response. This understanding of P mobilization under variable conditions during spring flush events can then be extended to other parts of the Lake Champlain watershed.