Winter Canola for Livestock Feed and High Seed Yield.

Brassica crops are an underutilized rotational crop grown in temperate climates of Europe, Australia, Canada, and the United States.  These crops are typically grown for either forage or seed production, however recent interest in dual-purpose crops may provide an opportunity for winter canola (Brassica napus) producers.  By planting winter canola in the spring, leafy forage production can be maximized before harvesting subsequent seed yield over a two-year span.  This could increase producer profit margins for this rotational crop.  Winter canola cultivars ‘Athena’ and ‘Baldur’ were sown in springtime and grown over two field seasons (2007-2008 and 2008-2009) in Moscow, ID.  Vegetative biomass during the first year was harvested and ensiled to perform chemical analysis and determine forage quality and yield.  Treatments over both years included two cultivars, three planting densities (4.5, 6.7, and 9.0 kg ha^-1), and four planting dates (May, June, July, and August).  Together, the two highest planting densities yielded significantly more ry matter forage, but no difference was detected for seed yield.  Average total dry matter yield was greatest for spring sown winter canola (5.9 Mt ha^-1), while August seeded canola yielded 2.0 Mt ha^-1.  No significant differences were found between planting dates for seed yield.  However, when plants were cut for silage, earlier planting dates Produced higher seed yields than later plantings.  However, the last planting date, which was not harvested for silage, had the highest seed yield (2,545.6 kg ha^-1).  Both cultivars performed similarly over all treatments for forage yield and quality.  Neutral detergent fiber and acid detergent fiber of canola silage (Canolage^™) were both extremely low (24.9 and 21.9%, respectively), while crude protein levels were consistently high (20.3%) and comparable to alfalfa.  Crude fat and ash content of canola silage were both higher than expected.  Ash content in Brassica crops is naturally high, however, high pH levels (5.14) in this study indicate poor ensiling and likely excessive dry matter losses that increased ash content beyond normal levels.  Overall, quality for winter canola silage was exceedingly high, but forage yields were less than attractive.  Further agronomic research, and possibly plant breeding selection, is needed to identify optimal forage yields under irrigation in order to compete with alfalfa for acreage.