Features
Using weather modelling projects to help make decisions

Two new western Canadian research projects aim to offer producers improved risk modelling and rules of thumb for decision-making in extreme weather conditions.

The first, led by University of Manitoba researcher Paul Bullock in collaboration with Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry and Agriculture and Agri-Food Canada, aims to develop a Fusarium Head Blight (FHB) risk assessment tool.

The second project, co-led by Manitoba Agriculture systems modeller Timi Ojo and AAFC research scientist Ramona Mohr in collaboration with University of Manitoba researchers and Manitoba Agriculture, will offer producers a nitrogen (N) management decision tool for extreme moisture conditions based on local historical weather trends.

Both projects aim to offer producers valuable tools for decision-making based on the best available science.

Fusarium risk
Fusarium is a major concern to western Canadian producers. Infection represents multiple risks to producers, including reduced yield, reduced quality via Fusarium damaged kernels (FDK) and mycotoxin (DON) contamination. Ojo says fields with high percentages of FDK – 2.2 per cent or higher – can cause losses of about $89 per acre when grade 1 is downgraded to feed.

To mitigate economic risk, some producers spray as a precautionary measure regardless of actual risk levels. The goal of the project, therefore, is to develop a tool that can predict the likelihood of disease incidence based on weather conditions prior to anthesis, so farmers can be assured of the economic value of refraining from spraying during low-risk periods – and be prepared to spray at times when conditions are favourable for disease incidence.

Risk factors for FHB are well-known, but the new project promises several gains on past research efforts. The project will focus on barley and durum as well as spring and winter wheat, Ojo says. “FHB may affect the other cereals differently than the way it affects spring wheat.”

The model used to predict FHB risk hasn’t been validated in more than 15 years in Manitoba, he adds. “We know that the pathogen doesn’t stay the same – it adapts over time. So we want to check whether the thresholds for temperature and humidity are still correct or whether we need new thresholds.”

In the past, researchers have used models to predict risk at the provincial level, which can create dilemmas for producers farming in border regions if, say, Saskatchewan models are predicting high FHB and DON risk and Manitoba models are predicting low risk.

“Because of the issue around the border, we decided to engage our colleagues in Saskatchewan and Alberta to see if we can develop a Prairie-wide model,” Ojo says.

The project utilizes plot data from 15 locations in all three Prairie provinces each year between 2019 and 2021 as well as field data collected from more than 200 farmers’ fields. The end goal is to release an interactive web tool that predicts FHB and DON risk by 2023. Individual producers should be able to customize the tool based on seeding date, location and resistance level, Ojo says.

N management
The second project aims to create some rules of thumb to help producers assess and manage potential risks associated with N fertilizer application under extreme moisture conditions, Ojo says.

“Manitoba can have extremely variable moisture conditions, ranging from drought to flooding, sometimes in the same crop year. These moisture extremes can affect how efficiently fertilizer N is used by the crop,” Mohr explains.

For example, she says, wet conditions can result in significant N losses through denitrification and leaching – which also represents an economic loss to the producer. Selecting appropriate N management practices using the 4Rs (right source, right rate, right time, right place) can reduce risk.

“The challenge is that the ‘right’ best management practices under a certain set of moisture conditions may not be the best approach under a different set of moisture conditions,” Mohr says. “Unfortunately, accurately forecasting soil moisture conditions in the longer-term isn’t possible with today’s technologies.”

The project’s goal is to create a tool that takes into account soil moisture conditions based on soil type, specifically the risk of extreme moisture during critical periods of the growing season, based on historical weather trends, to help create a set of guidelines for N management.

Ojo says his team has 72 years worth of data on rainfall during the growing season dating back to the 1950s. Based on the data, he can look at a particular week and assess the probability that a given region will receive rainfall during that week. The tool also takes current soil moisture levels – gleaned from weather stations – into account, as well as soil types of different regions.

“We aim to provide Manitoba producers with a quantitative measure of the relative risk of moisture extremes in their region during critical parts of the growing season, which may help to inform a range of management decisions. This type of information is not currently available for Manitoba producers,” Mohr says.

“With respect to N management, we also aim to provide producers with information to help assess and manage the relative risks versus benefits of different N management decisions by taking into account both the current moisture conditions on their farm, and also the probability of extreme moisture conditions going forward based on historical weather data.”

This project is part of a larger extreme moisture initiative supported by the Manitoba Canola Growers Association, Manitoba Wheat and Barley Growers Association and Manitoba Pulse Growers Association, with support from the Canadian Agricultural Partnership.