Seasonal runoff under fallow, permanent pasture and continuous corn systems on a sandy loam in Eastern Canada

Erosion plot study was conducted during 2 consecutive growing seasons (May to September) on a sandy loam with 9 % slope to evaluate the effect of 4 cultural practices used in Eastern Canada on the rate of soil removal. Water runoff and nutrient transport. The 4 systems compared were: permanent pasture seeded with a mixture of alfalfa-timothy (Medicago sativa L., Phleum pratense L.), fallow consisting of uncultivated base soil produced by treating with atrazine to control weeds, and conventional and no-till silage corn systems. The conventional monoculture system consisted of fall moldboard plowing, spring disking with 2.2 kg/ha of atrazine applied to control weeds, and seeding. For the no-till system, corn was seeded directly into a grass-legume sod that had been treated with atrazine at 4.5 kg/ha a few days prior to seeding to kill the sod. Runoff was measured for the two corn systems for cropping period 1: from seed bed preparation to 1 month after planting; period 2, from 1 to 2 months after planting and period 3: from end of period 2 to harvest. Plots (3 m wide and 15 m long) were planted up and down the slope with silage corn (Zea mays L.). Runoff was collected into sedimentation tanks to be converted to soil loss in t/ha. Significant differences (P.01) between the four cultural practices occurred for soil loss and water runoff. The least soil loss was obtained with pasture which reduced soil loss (C-Factor) to less than 1 % for bare ground whereas with no-till and conventional corn systems soil loss was reduced to 3 and 40 percent respectively. Runoff of the bare plot was highest at 19 % of the rainfall, followed by conventional corn (10 %), no-till (3.5 %) and permanent pasture (2.3 %). The C-Factor for the two corn systems was the highest for period 1 and the lowest for period 3. No-till system reduced the annual average C-Factor by 92 % when compared with the conventional system. Nutrient losses decreased in the following order: conventional corn system fallow no-till corn system continuous grass-legume cover.