By: Gary Kruger, PAg, Irrigation Agrologist, Crops and Irrigation Branch
Yields for canola have risen to new heights in recent growing seasons, but growers are interested in pushing them even higher. Growers are also interested in whether boron application will further boost canola yields. Research in the 1990s and 2000s illustrated limited potential, but new varieties may have greater requirements and an ability to respond to an increased supply of boron. Sensitive crops such as alfalfa and canola have demonstrated visual symptoms suspected to be deficiencies on numerous occasions on susceptible soils. Many research agencies have conducted field testing with both liquid and granular boron forms applied to suspect soils using a variety of methods and timings, but few have demonstrated yield responses.
Boron is a soluble plant nutrient that is mobile in the soil. Primary sources available in the soil include organic matter and clay content. Flushing of boron from the soil profile by precipitation can reduce the supply of boron to canola. Capillary rise of boron with salts from deeper in the soil will contribute to improved boron supply from the soil to canola under dry conditions. A critical level for the boron soil test has not proven successful in separating responsive from unresponsive sites.
When rainfall is more frequent, less irrigation is required to grow the crop. The supply of boron to crops with irrigation water is about 0.05 lb boron per acre inch applied. When drier conditions return to Saskatchewan, the contribution of boron dissolved in irrigation water will increase proportionately as the rate of irrigation increases.
Yield response of canola to foliar boron during the 2016 growing season was 4 to 6 bu/ac on two of the three Agriculture Demonstration of Practices and Technologies (ADOPT) sites, which were conducted in cooperation with the Irrigation Crop Diversification Corporation (ICDC). The impact on canola growth was detected by NDVI imagery taken in mid-August on one of the fields, as shown in Figure 1. The area corresponding with boron application to canola at Riverhurst is the darker green polygon along the left hand side of the NDVI image.
Additional projects conducted during 2017 will evaluate whether the plant tissue boron content at early rosette stage is useful as a guide for predicting the likelihood of canola response to foliar boron application.
For more information, contact Gary Kruger, Irrigation Agrologist, at 306-867-5524 or firstname.lastname@example.org.