Dual-Purpose Winter Canola: Forage and Grain Production.

A study was conducted at the Washington State University Irrigated Agriculture Research and Extension Center to investigate the effect of N and S fertilization on yield, nitrate and sulfur composition on winter canola forage, and the effect of forage harvest on subsequent grain yield and fatty acid concentrations. Winter canola was planted in mid-August 2014 and 2015, forage was harvested approximately 60 days after planting and grain was harvested in mid-June to early July. Plots received either 112 or 224 kg N ha^-1 and 0, 22, or 45 kg S ha^-1 with or without a urease inhibitor. Plots were subjected to a dual-purpose cropping treatment (DPWC) and a grain-only cropping treatment (GOWC). Forage yields averaged 2.1 – 2.2 Mg DM ha^-1 with no differences among fertilizer treatments. Forage DM was low, ranging from 90 –210 g kg^-1. Forage nitrate levels were low (<1.09 g NO₃ kg^-1) however, forage sulfur levels were high ranging from 3.75 – 6.24 g S kg^-1, increasing as S fertilization increased. Cropping treatment did not influence winter stand survivability. Grain yields did not differ among fertilizer treatments, but GOWC grain yield was reduced in 2015 compared to 2014. Dual-purpose canola is an economically viable option, with the added income from the forage. Additionally, variable costs of DPWC and GOWC were similar as the only additional cost for DPWC was forage harvest. Dual-purpose winter canola can provide producers with 2 Mg DM ha^-1 of valuable forage, with no adverse effect on canola winter survivability and little effect on grain yields given the proper growing conditions and grazing or harvesting management.