Agricultural Practice Monitoring and Evaluation

Braun, D., and Meals, D. Stone Environmental. (2019). Agricultural Practice Monitoring and Evaluation (Technical Report No. 94). Grand Isle, VT: Lake Champlain Basin Program

• Dataset 1

Runoff from two study watersheds in a cornfield in Charlotte, Vermont was monitored between October 1, 2015 and April 22, 2019 to evaluate the effects of construction in September 2017 of a grassed waterway in one of the watersheds. Flow rate and water quality data were obtained from 51 runoff events prior to construction of the grassed waterway and from 41 events following construction.

For each runoff event, data were aggregated to calculate total flow and runoff depth, mean concentrations of several fractions of phosphorus and nitrogen as well as chloride and total suspended solids, and total mass loads for the same monitored constituents. Total mass loads of constituents transported from the study watersheds during each runoff event were divided by the areas of the watersheds to calculate areal loads (mass per unit area) to facilitate comparison with data from other Vermont fields. All data were log10 transformed to meet the assumptions of parametric statistical tests.

Constituent concentrations and loads recorded at the Charlotte study watersheds were generally within the range observed at the other Vermont edge-of-field monitoring sites between 2013 – 2019 (Stone Environmental, 2016), with a few exceptions. Areal loads of total suspended solids from both Charlotte study watersheds were substantially higher than those recorded at the other monitored fields. Mean chloride concentrations from the Charlotte watersheds were at the very high end of the range observed across all the other monitored fields and areal chloride loads were substantially higher than those observed at other monitored fields.