The Response of Wheat, Field Pea, and Canola Growth to Varying Forms and Application Method of Copper, Zinc, and Boron Fertilizers in a Range of Canadian Prairie Soils.

Copper (Cu), zinc (Zn), and boron (B) are the essential plant micronutrients most often deficient for cereal, pulse, and canola production in prairie soils, respectively. Higher yielding varieties and crop removal may lead to more micronutrient deficient soils. The objective of this three-year greenhouse study was to examine the effect of different forms and application methods of fertilizer Cu, Zn, and B on yield and nutrient uptake of spring wheat, field pea, and canola grown in a simulated rotation within variety of Canadian prairie soils. Fifteen soils (12 mineral and three organic) were collected throughout Alberta, Saskatchewan, and Manitoba; representing the diversity of arable prairie soil types, along with varying initial available soil Cu, Zn, and B levels. The fertilizer treatments included different forms (Cu/Zn sulfate salt and chelated forms, and boric acid) and application method (banded and foliar). The effect of residual soil banded micronutrients (alone or combined) were also examined in the second (field pea) and third (canola) growing seasons. Banding of CuSO₄ and ZnSO₄ was the most effective application method supporting increased Cu and Zn uptake by wheat and pea, respectively. Unlike fertilizer Cu, which increased wheat yield on the Cu-deficient mineral and organic soils, the Zn fertilizer had a limited effect on pea yield, due to adequate soil Zn fertility. Residual Cu fertilizers from the previous wheat crop were the only treatments to consistently increase pea grain yield compared to the unfertilized control for most soils. Pea is considered to be tolerant of low soil Cu, so this could be related to the fungicidal properties of Cu to suppress root disease. The peas grown with residual CuSO₄ + ZnSO₄ in mineral soil had less biomass compared to ZnSO₄ alone and this negative interaction merits further investigation.