• University of Saskatchewan
• Yields

Objective

To determine the crop response to foliar applied phosphorus (P) fertilizer, applied alone and in combination with soil applied P. To determine the efficiency of the added P fertilizer in recovery by the crop and increasing the yield.

Outcome

This study evaluated the response (agronomic, nutritional, and environmental) to foliar mono-potassium phosphate (KH2PO4) fertilization of canola, pea and wheat grown in brown, dark brown and black soils in Saskatchewan. Of the three crops, canola was the most responsive to foliar phosphorus (P) fertilization in terms of yield and phosphorus uptake response, followed by wheat and pea. Pea showed little response to phosphorus fertilization in general, attributed to its ability to effectively scavenge soil reserves of phosphorus. Evidence of phosphorus uptake through canola and pea leaf material was observed, but foliar phosphorus application did not effectively balance off the yield lost by reduced rates of seed-placed MAP fertilizer. Foliar phosphorus fertilization at the rates applied in this study had limited effect on human nutritional value of the grain as assessed through effect on grain zinc (Zn), iron (Fe) and phytate concentrations. Furthermore, there were no large discernible impacts of proportion of phosphorus applied in foliar versus soil applied on the dissolved reactive inorganic phosphorus (DRP) measured in simulated snowmelt runoff from post-harvest soils in controlled environment and field studies. It is concluded that mid-season foliar phosphorus applications would be most suitable for a top up of phosphorus nutrition applied in small amounts under conditions of soil phosphorus deficiency rather than a substitution for seed row applied phosphorus fertilizer.

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