The effects of short-term grassland set-asides on soil properties in the Fraser River delta of British Columbia
The Grassland Set-Aside Stewardship Program provides cost-share payments to agriculture producers in the Fraser River delta (FRD) region of British Columbia for placing active cropland under a grass and legume vegetation mix for a one to four-year period. While long-term grassland set-asides (GLSA) have been found to improve soil structure, reduce compaction, and increase soil organic matter; short-term set-asides (<five years) are less common and less studied. The objective of my research was
... of my research was to evaluate the effects of short-term set-asides on select soil properties during the first two years of enrolment in the FRD. A total of eight fields entering the GLSA program were assessed prior to seeding for soil physical and chemical properties commonly associated with crop productivity in the region. The selected soil properties of fields entering the GLSA program were found to be highly variable, and two fields contained properties commonly associated with poor crop productivity. Following GLSA seeding, these unproductive fields were noted to have poor GLSA vegetative growth during the first two seasons of enrollment and a similar bulk density, aeration porosity and aggregate stability relative to fields managed for annual crop rotations (ACR). In contrast, productive GLSA fields entering the program were found to have a higher aggregate stability, higher aeration porosity, and lower bulk density than paired ACR fields after a single season of establishment. A further analysis for total soil organic nitrogen, total soil organic carbon, and active soil organic matter pools, did not identify differences between ACR fields and paired productive GLSA fields after two seasons of establishment. These findings indicate that productive fields entering the GLSA program have improved soil structure and less compaction than ACR fields after two years of enrollment, while unproductive fields entering the program may require additional accompanying management practices or an extended enrollment period for differences to occur.