Demonstrating benefits of seeding date and rate on canola yield and quality

Project Summary

Overview

Early seeding typically results in better yielding crops, especially for canola, barley, wheat, peas and oats (Weir, 2019). But not all crops can be seeded early. In 2022, some parts of Saskatchewan were seeded late due to excess spring precipitation, and while other parts of the province could seed early, but they struggled with a moisture deficit (Warner, 2022). Many producers had to choose between early seeding, reseeding and late seeding their canola crops. However, due to the high cost of inputs, some producers may be hesitant to seed earlier.

Objectives

This study investigated how a canola crop performs with different seeding dates. It also incorporates two different seeding rates, as seeding rate may reduce the severity of risks associated with seeding too early or too late. Seeding dates or rates can also be beneficial for flea beetle control.

The main two objectives of this demonstrative study are:

1. Demonstrate how different seeding dates and rates can improve canola yield and quality.

2. Provide a backdrop to discuss methods of flea beetle control and proper scouting techniques at Field Days and/or extension activities.

While both of these methods were included in a 2019 ADOPT study, the canola used was untreated, which is not common practice. There were also only two different seeding dates and the higher seeding rate was not successfully established.

Field trials

Researchers tested five seeding dates – starting with early May and then seeding plots every 10-14 days, ending with a late June planting. Each seeding date also included low and high seeding rates. Low seeding rate at the three dryland sites was 80 seeds per square metre and the high rate was 160 seeds per square metre.

Wheatland Conservation Area (WCA) in Swift Current, Northeast Agriculture Research Foundation (NARF) in Melfort, Irrigation Crop Diversification Corporation (ICDC) in Outlook, and Conservation Learning Centre (CLC) in Prince Albert each hosted these trials in 2023.

Results

Overall, yields decreased when canola was seeded late in June. Yield losses for these very late seeding trials were up to 48 per cent in Prince Albert, 50 per cent in Melfort, 87 per cent in Outlook, and 91 per cent in Swift Current. Late-seeded canola also had lower oil content. These yield and quality issues were related to issues with uniform dry down and harvest delayed to as late as October 25.

Seeding rates were included in this study to demonstrate how the practice can compensate for high seedling mortality during unfavourable growing conditions, especially for early seeded canola. In 2023, conditions were dry compared to long term averages, but anticipated risks such as high flea beetle pressure, cool soils and frost damage did not occur.

High seeding rates are still recommended to target minimum plant stands, as seed mortality was often 50 per cent or greater in these trials.

This study clearly demonstrated that, when spring conditions are favourable, early seeding is a recommended practice to maximize yield potential.

While difficult to predict the likelihood of flea beetle pressure in an upcoming growing season, it would be valuable to repeat this demonstration with higher flea beetle populations. Selecting an earlier seeding date could help showcase how less desirable growing conditions can affect canola yields and how seeding rates can help compensate and reduce yield losses. This trial was done again this year (2024) at NARF, ICDC, WCA and WARC. Seeding rates stayed the same, but seeding dates were earlier.

References

Warner, B. 2022. Flea beetles and frost damage prompt reseeding of canola in Saskatchewan. Real Agriculture. Retrieved November 15, 2022
Weir, T. 2019. Risk and Benefits of Early Seeding. Farmers Edge. Retrieved November 16, 2022.