LAUSR

Abstract: Factorial experiments were conducted at two locations in Quebec to measure the combined effects of cover crop (CC) [mix of red (Trifolium pratense L.) and white clover (Trifolium repens L.)], fertilizer type [mineral (27–0–0) or organic (pig slurry)], and nitrogen (N) rate (0, 50, 100, 150 kg N ha-1) on canola (Brassica napus L.) yield and N uptake in a split-plot design reproduced twice (2013–2014 and 2014–2015) at each location. At crop killing, the clover biomass contained 28–151 kg N ha-1. Cover cropping did not change canola N uptake but increased yield and had a mineral fertilizer replacement value of 22–82 kg N ha-1. Without N fertilizer application, CCs increased canola yields by 6%–42%, diminishing with increasing fertilizer N rate. Canola N uptake and yield were lower with pig slurry compared with the mineral fertilizer. Maximum canola yield was reached at rates of 120 kg N ha-1 and higher with the mineral fertilizer. Therefore, clover CCs may help reducing fertilizer application rates in canola without compromising yields.