Principal Investigator: Christian Lenhart
Organization: University of Minnesota, Bioproducts and Biosystems Engineering
Award Amount: $64,286
Start Date: March 2019 | End Date: December 2020
Project Manager: Aicam Laacouri (Aicam.Laacouri@state.mn.us)
The overall goal of the project was to provide an assessment of long-term effectiveness of cover crops on dissolved phosphorus and nitrate. The main objectives were:
- Assess the effectiveness of cover crops at removing nitrate and dissolved phosphorus based on field data from tile drain outlet and edge of field monitoring on an agricultural field in Martin County between 2012 and 2018, with an additional year of data collection in 2019;
- Collect economic data on cover crop management and two other best management practices (BMPs) for costs-benefits analysis.
Highlights
- Cover crop implementation reduced nutrient loads and concentrations in drain tile
- Nitrogen, total and dissolved reactive phosphorus removal costs of $13, $955 and $1,720 per kilogram per hectare
- Cover crop implementation improved downstream management practice performance
Summary
The conservation practice of cover crop adoption, expanding rapidly in the Midwest United States in recent years, has been shown to be one of the most cost-effective practices for reducing nutrient loss from agricultural landscapes. In particular, cover crops may aid in the prevention of nutrient losses through drain tile, a common and necessary agricultural practice for removing excess soil moisture. When implemented as part of an agricultural treatment train, a series of management practices placed across a landscape gradient, cover crops may also serve to improve both cost and nutrient removal efficiencies of downstream practices.
Through modeling techniques and field monitoring spanning 2013-2019 at a southern Minnesotan agricultural demonstration field site, this study aims to characterize total nitrogen, total phosphorus, and dissolved reactive phosphorus concentrations and load reductions provided by cover crops. Direct implementation cost estimates and nutrient removal performance improvements provided by cover crops to a downstream treatment wetland were also analyzed. Analysis of drain tile water quality and quantity data showed annual concentration reductions of 48%, 75% and 63% and annual load reductions of 9.13, 0.12 and 0.07 kilograms per hectare for total nitrogen, total phosphorus and dissolved reactive phosphorus, respectively. Direct cost estimates for these cover crop reductions were $13.96, $955, and $1,720 per kilogram, per hectare, per year. Cover crops improved annual nutrient removal cost of a downstream wetland by $18.47 per kilogram for total nitrogen and $211.38 per kilogram for total phosphorus.
