An Assessment of MitAgator: A Farm-Scale Tool to Estimate and Manage the Loss of Contaminants from Land to Water

Abstract

Land users and managers require decision support tools (DSTs) that enable them to estimate losses of contaminants from land to freshwater. MitAgator is a DST that estimates losses of nitrogen (N), phosphorus (P), sediment, and fecal indicator bacteria (E. coli) and the cost-effectiveness of different strategies to mitigate losses so that a water quality target can be met at the least cost. Some of the algorithms present within Overseer (a standard DST used in New Zealand for N and P management) have been modified and appended to include spatial analysis in MitAgator. Outputs from MitAgator showed good (R 2 > 0.77; p < 0.001) prediction of measured N and P losses across a range of land uses, but accuracy decreased at larger (catchment) scales. Analysis for P outputs indicated that the most sensitive inputs were hydrological characteristics, followed by soil characteristics and P inputs. Although national databases are used for many of these inputs, if better local data are available, then they should be used. Furthermore, while MitAgator is easy to use by a novice, MitAgator outputs should only be interpreted in collaboration with an experienced user so that limitations concerning cost-effectiveness estimates and spatial and temporal scales are not exceeded.

A Global Perspective on Phosphorus Management Decision Support in Agriculture: Lessons Learned and Future Directions

“…The plans can recommend actions based on either expert knowledge or quantitative cost effectiveness generated by field trials (Beef and Lamb New Zealand, 2019;Canterbury Water, 2019). At their most sophisticated, farm plans include the use of calibrated software that models P losses from the farm, the contribution from CSAs, and places and times their actions across the farm to meet a targeted percentage reduction (McDowell et al, 2015). Using such software to target P mitigation measures has enabled farmers to reduce costs more effectively than if their actions were spread across the entire farm.…”

“…However, as eutrophication issues have persisted and early actions were insufficient to prevent water quality degradation, DS has increasingly involved adaptive management, with older systems being updated (e.g., P Index in the United States) and new systems emerging to address particular priorities (e.g., CSA identification in the UK, buffer placement in Finland). Where new knowledge has been incorporated from localized experience, or acquired from the experience of other jurisdictions, the use and outcome of DS in improving water quality has been promising (e.g., McDowell et al, 2015), especially when some legislative backbone supports the use of DSTs and DSSs. For example, Ulén et al (2007) notes that in Norway, Sweden, the UK, and Ireland "integrated legislative, regulatory, and economic instruments together with targeted information campaigns and individual support through the extension services are common practice."…”

International Watershed Technology: Improving Water Quality and the Environment

“…McDowell et al (2016) describe a farm-scale tool for compiling, processing, and visualizing large amounts of data for optimizing the cost and effectiveness of contaminant mitigation strategies. The MitAgator DST estimates farm-scale losses of nitrogen, phosphorus, sediment, and fecal indicator bacteria (E. coli) and allows users to test the costeffectiveness of different strategies to mitigate losses, thereby identifying the least-cost strategy to achieve the water quality target.…”