Effects of planting direction of brussels sprouts and previous cultivation on water erosion in southwestern British Columbia, Canada

ABSTRACT:

Eight erosion plots were monitored under natural rainfall conditions from 1989 to 1991 to evaluate the effects of planting direction and slope steepness on soil loss and runoff from a brussels sprouts field, which had been continuously cultivated, in the upland area of the Lower Fraser Valley in southwestern British Columbia, Canada. An additional two erosion plots on adjacent land that had not been used for annual cultivation for the past 30 years were compared with two of the previous eight plots, to determine the effects of previous cultivation on soil loss, runoff and yields of brussels sprouts. The soil was a Whatcom silt loam (fine, mixed, mesic, Typic Haplorthod). Results showed a significant slope effect on soil loss and runoff, with a doubling of slope steepness from 5% to 10% resulting in a more than doubling in both soil loss and runoff. The effects of cultivation and planting direction on soil loss and runoff were not conclusive. Plots in the previously uncultivated field had on average 85% lower soil loss, 72% lower runoff, and a doubling in yields of brussels sprouts than the plots representing prolonged cultivation. Soil losses were found to be low [<1 t/ha/yr (<0.5 t/ac/yr)], as a result of good crop canopy protection and high amounts of surface residues from brussels sprouts leaves at the time of heavy rains.