Effect of preceding glyphosate application on nutrient levels in soybean

Crop Soybean
Start Date2017
End Date2018
Principal InvestigatorMohr, Ramona, Agriculture and Agri-Food Canada
MPSG Financial Support$12,305
Total Project Funding$24,610
External Funding PartnersAAFC
ReportMohr – Glyphosate – FINAL report 2019

Research Objectives

The proposed study would provide preliminary information regarding the potential effect of repeated field applications of glyphosate over the preceding four-year period on nutrient uptake, yield and quality of soybean under Manitoba conditions, which is not currently available.  As the experimental site is already established, it provides a unique opportunity to investigate the effect of repeated applications of glyphosate, without requiring a multi-year investment to establish this type of study.

Project Description

Glyphosate is widely-used in Manitoba cropping systems, and may be applied multiple times in a single growing season.  The extensive use of glyphosate has raised some questions regarding potential effects on crop production and nutrient uptake.

A field experiment has been conducted near Brandon, MB since 2013 to determine the effect of repeated glyphosate applications on crop growth and nutrient uptake of major crops (wheat, canola, field pea) in western Canada.  This experiment was part of a multi-year, multi-site study led by Dr. Bob Blackshaw (AAFC-Lethbridge) and conducted at various locations across western Canada.  The original study concluded in fall 2016, and the experiment at Brandon was left undisturbed this fall.  This experiment provides a unique opportunity to collect preliminary information regarding the potential effects of repeated field applications of glyphosate on macro- and micro-nutrient uptake by soybean, and on soybean yield, since soybean had not been included in the original study.  While the proposed study falls under the research priority area of “Soil Ecology and Fertility”, it does not directly address the specific research priorities outlined under this priority area.

In order to determine the effect of repeated glyphosate applications on nutrient uptake, yield and quality of soybean, the existing experiment would be planted to soybean for the 2017 growing season, and macro- and micro-nutrient concentration and uptake, crop yield and quality would be determined.