Response of canola, wheat, and pea to foliar phosphorus fertilization at a phosphorus-deficient site in eastern Saskatchewan

Foliar fertilization is a potential strategy to supplement phosphorus (P) requirements when conditions permit. In 2016 and 2017, canola, wheat, and pea were grown in a randomized complete block design trial near Pilger, SK, Canada. Each crop received a total P application of 20 kg P 2 O 5 ha −1 , with varying proportions of the P applied as seed-placed monoammonium phosphate (MAP) supplemented with foliar KH 2 PO 4 (0%, 25%, 50%, and 100%) applied prior to anthesis. Under field conditions, yield response decreased as the proportion applied as seed-placed MAP decreased. The 100% foliar-applied P treatment in canola was able to maintain significantly higher yield than the unfertilized control in the absence of seed-placed MAP, indicating some uptake and response. Of the crops evaluated, canola was most responsive to P fertilization. Phytate content ranged from 68% to over 90% of total seed P, with the highest proportions found in wheat grain. Foliar P application had limited effect on phytate and grain iron content, but there appeared to be an inverse relationship between seed-placed MAP and grain zinc concentration that was less evident when P was applied in foliar form. In this study, foliar P application was unable to substitute for seed-placed MAP and overall had a marginal effect on grain yield and P uptake as well as seed nutritional value.