Spatial Targeting of Conservation Tillage to Improve Water Quality and Carbon Retention Benefits

This paper develops a GIS-based modeling framework that integrates a farm model, a hydrologic model, and a soil organic matter model to examine spatial targeting of conservation tillage to jointly improve water quality and carbon retention benefits in agricultural watersheds. Previous studies have examined the targeting of conservation tillage, land retirement, and riparian buffers at watershed scale to achieve water quality benefits but not considered carbon retention benefits. An empirical application of the framework in the Fairchild Creek watershed in Ontario shows that targeting conservation tillage based on sediment abatement goal can also achieve comparable carbon retention benefits in terms of percentage reduction of its base carbon losses. The targeted subcatchments for conservation tillage vary across the watershed based on benefit to cost ratios. The pattern of conservation tillage targeted based on carbon retention goal is similar to that with a sediment abatement goal but slight differences are found because of different carbon content in the soils. The modeling results have important policy implications for the design of conservation stewardship programs such as setting sediment abatement goal as an indicator to achieve joint environmental benefits and direct public fund to locations that can achieve environmental goals at least costs.