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UBC Theses and Dissertations

Effects of grassland set-asides on selected soil properties in the Fraser River Delta of British Columbia Yates, Dru Everett


Grassland set-asides (GLSAs) have been used to encourage environmental stewardship on agricultural land in the Fraser River delta of British Columbia (BC) since 1994. Through this Grassland Set-aside Stewardship Program, farmers plant a mixture of grasses and legumes in place of harvestable crops for a minimum of one full year and the farmers then receive payment for establishing these short-term grasslands. Grassland set-asides are typically established on degraded fields. Although improving long-term soil quality is a key objective in the GLSA Program, evaluations of GLSA management effects on the soil have been few and limited in scope. The objectives of this study were to determine the effects of GLSA management and GLSA age on selected soil properties in agricultural fields in the Fraser River delta. Three GLSA field sites – ranging in age from two, three, and six years – were compared to three adjacent cropped potato fields for the following soil properties: total soil C and N, mechanical resistance, bulk density, aeration porosity, and aggregate stability. Relative to the Cropped treatment, the GLSA treatment did not result in an increase in total soil C or N, but did result in lower soil mechanical resistance in the upper 30 cm depth, and higher aeration porosity, and aggregate stability. The differences observed between the Cropped and GLSA treatments were most pronounced on the site with the six-year-old GLSA, indicating reduced compaction and improved soil structure as a GLSA ages. Baseline measurements of the soil prior to GLSA establishment are recommended to track changes to the soil over time and to improve the efficacy of GLSA management as a remediation strategy by pinpointing underlying soil issues that could be addressed through other corrective management (i.e. sub-soiling, liming, etc.). Soil mechanical resistance, aeration porosity, aggregate stability, pH, salinity, and mineralizable N are suggested as valuable, responsive indicators of GLSA management effects on the soil.

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