The use of cover crops for nutrient conservation
Field experiments were conducted in 1990 and 1991 on a sandy loam soil at Ayr and a loam soil at Woodstock to evaluate the effectiveness of cover crops for nutrient conservation. Three cover crops, oilseed radish, annual ryegrass and red clover were established in 1990 in or following harvest of barley and winter wheat to which 1/2, 1 and 2x the recommended rates of N had been applied. Attempts to establish cover crops in corn were largely unsuccessful. Cover crops were sampled periodically to determine biomass production and N and P uptake. Soil and soil solution samples were taken periodically in the fall of 1990 and spring of 1991 and analyzed for NH4+ and NO3 nitrogen. Corn was grown on all plots in 1991 without N addition to evaluate the release of N from the cover crops. The potential for contribution of N and P to surface runoff by leaching from cover crops during the winter and spring was evaluated in laboratory leaching studies using a rainfall simulator.