Impacts of Incorporating Prairie Vegetation within Row Crop Production on Soil Hydraulic Properties

Abstract

Runoff from agricultural land is a concern for downstream water quality. Soil hydraulic properties influence infiltration which influences surface runoff and, as a result, downstream water quality. Implementation of vegetative filter strips (VFS) has the potential to reduce downstream pollutant loading by slowing runoff velocities, which allows particulates to settle out, as well as allowing for infiltration. Since soil hydraulic properties influence infiltration there is a need to evaluate the impacts VFS have on physical properties of the soil, which will allow for a better understanding of the mechanisms by which VFS provide benefits. The objective of this study was to determine if differences in soil hydraulic properties exist under different land uses. Variations in surface infiltration between VFS, restored prairie, and agriculture row crop areas were determined utilizing tension infiltrometers for in-situ measurement of infiltration rate at the upslope and foot slope positions under various land cover in three small watersheds at the Neal Smith Wildlife National Refuge (NSNWR) near Prairie City, IA. Results did not show statistically significant differences in treatment at any of the tensions tested. There were significant differences in conductivity between the two landscape positions at tensions -6 & -12 cm. Although there were no significant differences collectively results did show higher conductivity within the VFS compared to the row crop and restored native prairie in two of three watersheds. Higher conductivity in the VFS of the two watersheds shows that over time VFS may influence soil hydraulic properties within a watershed. However the low conductivity in the restored native prairie does not seem to support the idea of long term effectiveness of VFS which warrant further investigation.