Effect of Foliar-applied Monopotassium Phosphate on High Yield Canola and Wheat Grown in Southern Manitoba

Assess foliar application of mono potassium phosphate (MKP) to enhance phosphorus nutrition of wheat.

IPNI-2001-CAN-MB15

01 May 2002

2001 Annual Interpretive Summary

Effect of Foliar-Applied Monopotassium Phosphate on High Yielding Canola and Wheat Grown in Southern Manitoba, 2001

Most soils in the prairie region of Canada are phosphorus (P) deficient for crop production and require P fertilization for optimum crop yields. However, the efficiency of P uptake from soil-applied P fertilizer may be poor during periods when the topsoil is cold or dry and diffusion of P is limited, causing a transient deficiency of P. The objective of this study is to explore the effectiveness of using a monopotassium phosphate (MKP) foliar application for canola production under high yielding conditions in southern Manitoba.

The MKP was applied as a foliar spray to canola at either the 2-3 leaf stage or the early flowering stage. Other treatments included a check (with no foliar fertilization), equivalent rates of nutrient P applied as foliar monoammonium phosphate ( MAP), and equivalent rates of potassium (K) applied as foliar potassium nitrate (KNO3).

In 2001, the first year of this study, overall yields were excellent at the irrigated, high fertility site and were low at the dryland site. Preliminary analysis of the yield data indicates no consistent pattern of response to the low rates of any of the foliar applied nutrients. Furthermore, although the results have not been statistically analyzed, yield differences appear to be small compared to variability within replicates at each site. Additional measurements, including tissue concentrations of P and K, soil temperatures, and anion and cation exchange membrane-available P and K, will be examined. MB-15F