Top-dress lessons from fertigation studies

Fertigation is applying fertilizer while watering through an irrigation system. Alberta Agriculture is running a study into fertigation on canola and wheat. In the study, fertigation was put on at three different stages — 5-leaf, bolting, and flowering — and then compared to plots where all nitrogen was applied at the time of seeding. The study has only one year of results, and so far they show that with canola, fertigation is — at best — equal to the treatment that received all nitrogen at the time of seeding.
Alberta Agriculture ran another in-crop N experiment in 2013 that came to a similar conclusion. This study compared yield response for various application timings for 80 kg N/ha (71 lb./ac.) rate. Canola suffered a yield penalty when the 80 kg/ha was split applied — with half applied at seeding and half applied prior to bolting — compared to treatments where all 80 kg/ha were present at the time of seeding.