Vegetated buffer strips are a management practice implemented in agricultural landscapes because of their effectiveness in reducing the transport of phosphorus (P) to surface water. However, in northern climates, buffers can become a source of P when soils are frozen and vegetation is dead or dormant during the most significant runoff period. This research investigated buffer vegetation as a potential source of P at the Morden Research Station, Manitoba. Vegetation sampling in two new buffers and an established buffer in fall 2015 and spring 2016 showed biomass P loss of 32-47% and an increase in soil Olsen P of 25-43% over winter. Thus, it is likely that much of the leached P was retained in the soil. Laboratory experiments subjected timothy grass to zero, three or six freeze-thaw cycles (FTCs), followed by extraction to leach P. Results showed an increased number of FTCs resulted in increased concentrations of leached P.
