Fall and early spring seeding of canola (Brassica napus L.) using different methods of seeding and phosphorus placement

Fall seeding of canola has been suggested as an alternative to spring seeding in order to avoid environmental stress, foster early maturity, produce larger seed and possibly realise yield and oil content benefits. Further, the practice of broadcast-seeding canola has been introduced to save time and allow fertilizer application while seeding in fields that are wet in the spring. This study was designed to assess methods of phosphorus p placement under these alternative seeding dates and methods. Canola was broadcast or seed-row placed either in the fall (14 to 28 October) or spring (26 April to 3 May) of each crop year. We assessed phosphorus fertilization for these options by either broadcasting or banding and seed-placing or side-banding 0, 20, and 40 kg P2O5 ha(-1) for broadcast and row seeding, respectively. Fall seeding of canola did result in earlier maturity (7 to 10 d) and larger seed in all experiments. Spring-seeded canola provided a yield advantage (average 14% over all six experiments), especially in the three experiments carried out in the Black Soil Zone (average yield increase of 24.8%). There was a response to phosphate fertilization in three of the six sites, which were considered to be phosphorus deficient. The effectiveness of phosphate application was associated with the method of seeding and thus phosphate placement, because row-seeded canola yielded higher at the phosphorus-deficient sites. Generally, there was no interaction between the time of seeding and phosphate fertilization. The results on the impact of seeding time on oil content were inconclusive as oil content increased at one site, decreased at another and remained unchanged at the rest.