Temporal and Spatial Dynamics of Nutrient Retention on Conventional Farms in Southwestern Ontario

Abstract

Nutrient losses from farms threaten environmental and human health globally. This thesis evaluates edge-of-field mitigation strategies, testing the hypothesis that downslope deep-rooted perennial buffers intercept nutrient leaching from crop fields. This thesis examined buffer interception of subsurface mobile nitrogen and phosphorus seasonally in sand versus clay soils, and contrasted findings with nutrient concentrations in nearby tile-drains, surface waters, and established drinking water standards. Overall, soil texture and climate influenced nutrient transport over interception by prairie buffer. Buffers intercepted nutrients during peak growth and at typical summer precipitation but were overwhelmed by high flood events. They were largely ineffective in spring prior to plant canopy development. Buffers can work as edge-of-field strategies, but only as one part of a farm-level effort to retain nutrients.