Winter Canola Response to in-Furrow Starter Fertilizer Application As Affected By Soil pH and Soil Test Phosphorus.

Proper fertility management is essential for a successful canola crop. Field experiments were conducted in Dacoma, El Reno, Fairview, Fort Cobb, Kingfisher, Lahoma, Lamont, Miami, and Perkins OK to evaluate the effect of applying di-ammonium phosphate (DAP, 18-46-0:N-P₂O₅-K₂O) in-furrow on crop grain yield. Di-ammonium phosphate was applied with the seed at planting at 22 and 30 lbs/ac in no-till (NT) and conventional till (CT) systems. Canola variety ‘DKW 46-15’ was seeded between September 10 to October 10, 2016 at 3 lbs/ac spaced at 7.5 (CT) and 15 in (NT). The experiments were replicated five times. Five of the ten locations responded to in-furrow application of DAP. Yield difference ranged from 1 to 5 bushels/ac. Locations that had both low soil pH and low soil test phosphorus (STP) generally had higher yield response (3-5 bushels/ac) than all other locations. No negative effects (i.e. stand count reduction) were observed with the addition of the starter fertilizer. Results indicated that it is important to account for both STP and pH completely when providing nutrient recommendations in winter canola.