How to estimate canola plant populations

There's a part of me that is hesitating to even blog about such basic things as plant counts. Why? Because the fields around here and much of the Prairies are struggling, just getting seeded or are unseeded. It's late in the spring seeding season and I don't want to be pouring salt into anyone's wounds.

That said, there certainly are parts of the west that are growing and so this is for them. My apologies if you're not one of them (but please don't shoot the messenger).

My former colleague and past editor of Grainews, Jay Whetter, is hard at work at the Canola Council rolling out agronomy tips. The latest release on estimating plant populations as a means of gauging seeding success caught my eye and I thought I'd share it. Knowing plant counts may also play a role in management decisions in the coming weeks regarding spraying or, ouch, reseeding. What follows is a summary of what Jay sent me.

Target 10 canola plants per square foot

According to Derwyn Hammond, senior agronomy specialist with the Canola Council of Canada, canola stands of 10 plants per square foot (100 per square metre) are ideal as they provide a cushion for loss due to frost, diseases or insects. Stands of less than four or five plants per square foot (roughly 40 to 50 per square metre) generally cannot reach their full yield potential. If a plant stand ends up at less than 10 plants per square foot, Hammond advises checking equipment settings, the seed lot and field conditions to identify why they did not achieve the ideal plant population.
 

Recording the average number of plants per square foot can help farmers improve their seeding methods for 2011. "You can keep records of thousand seed weight, seeding rate and seeding date, plus seeding depth and soil temperature, but what’s the point if you don’t also do plant stand counts?" says Hammond.

Plant stand assessment is also essential information for setting seeding rates in the future. Farmers who usually achieves above 10 plants per square foot under average conditions may have been able to trim costs with a lower seeding rate. But if plant populations are routinely at seven plants per square foot or less, reducing rates could spell trouble.

How to estimate plant populations

The Canola Council suggests using hoops equivalent to one-quarter of a square metre to estimate plant populations. Simply place the one-quarter metre hoop into the crop, count the number of plants inside and multiplying by four to get plants per square metre. Several counts per field are required to get a good average. Farmers considering reseeding should take 50 to 100 samples to be sure the plant count is accurate enough before making such an important (and costly) decision.

Farmers can make their own 50 cm by 50 cm (quarter-metre) square or make a hoop with an inside diameter of 56 cm, which is the equivalent of a quarter metre square, according to the Council's release. 

(Click on image for larger version) This hoop is equivalent to one quarter of a square metre. Inside this hoop are 23 plants, which works out to 92 plants per square metre — or roughly nine plants per square foot. That’s a good target. Photo courtesy the Canola Council of Canada