Features Agronomy Cereals
Traditional cereal seeding rates may be too low

Traditionally, cereals were sown in the 3/4 to one bushel per acre range, sometimes creeping up to 1-1/2 bushels. With the introduction of new, high yielding varieties of cereals and the understanding that a more dense plant stand helps with weed competition, researchers wondered if these traditional rates were high enough.

Brian Beres, a research agronomist at Agriculture and Agri-Food Canada at Lethbridge, Alberta, recently reviewed seeding rate trials conducted in western Canada in an attempt to help refine cereal seeding rates. “Except for malt barley or possibly solid-stemmed wheat for sawfly control, there is a case for increasing seeding rates for winter and spring cereals,” says Beres.

Cereal seeding rates may be too low to achieve high yields. Photo By Bruce Barker.

Malt barley seeding rates balance yield and quality
Ross McKenzie, with Alberta Agriculture and Food (AAF) and Lethbridge College, recently completed a comprehensive study on malt barley production and a key component looked at seeding rate. With malt barley, seeding rate was found to influence yield and kernel plumpness. Increasing seeding rates, to a certain point, did result in higher yields. However, as seeding rates increased, the amount of plump kernels started to decline. Since kernel plumpness is a key factor in malt barley selection, McKenzie found that seeding rate had to balance yield and quality factors.

In the research, McKenzie found that optimum seeding rate densities were 20 plants per square foot (200 plants per square metre) for dryland farms and 25 plants per square foot (250 plants per square metre) under irrigation.

“While increasing seeding rate did result in increased stand establishment, there was no significant difference in yield with more than 250 plants per square metre,” says Beres. “However, when you look at kernel plumpness, the amount of plump kernels declined with seeding rates higher than 250.” Beres notes that if growers are growing barley for feed, seeding rates can easily be increased by another 30 to 50 percent. Other research has shown that feed barley yields can be increased with seeding rates up to 45 plants per square foot (450 plants per square metre) in order to increase crop competitiveness and improve yields.

Spring wheat may also benefit from increases
Beres also has preliminary results on a trial looking at seeding rates for hard red spring and durum wheat. The trial is part of a wheat stem sawfly trial which included AC Lillian, CDC Go, a blend of those two spring wheat varieties and durum wheat AC Avonlea. Seeding rates were 15, 25, 35 and 45 seeds per square foot (150, 250, 350 and 450 seeds per square metre). There were two locations in the Dark Brown soil zone used in the trial, Nobleford and Coalhurst, both in Alberta.

The preliminary results of this study suggest that producers seeding durum and hard red spring wheat in continuous cropping systems would benefit by increasing seeding rates to at least 35 seeds per square foot. For a wheat variety like Superb, that would equate to about 2.35 bushels per acre.

“The trends in the study are something to consider for growers, particularly if they are on the lower end of the seeding rates,” explains Beres. “They may want to consider trying out higher seeding rates to see how their yield responds. The only exception would be solid-stemmed wheat, which performs better at a mid-range seed rate of 250 to 350 seeds per square metre. Exceeding this range may result in reduced pith expression or a less solid stem, making the plant more vulnerable to stem cutting by the wheat stem sawfly,” explains Beres. He adds that hollow-stemmed varieties should be seeded at higher rates as studies have shown that less cutting by sawfly has been observed with increased seeding rates.

Looking at all of the studies, the trend to higher seeding rates, except for malt barley and solid-stemmed cultivars, should help to optimize yield when using new varieties with higher yield potential. Perhaps the first place to start is to calculate seeding rates based on a targeted seeding rate, rather than simply with a bushels per acre seeding rate. Since many cereal varieties have different seed size, using a seeding rate calculator, such as the one found on AAF’s ‘Ropin the Web’ web site will help ensure targeted seeding rates are hit. -end-

More and more producers are looking at seeding rates as a management tool for increasing profit. Industry has done an excellent job of assisting producers in managing fertility levels, crop rotations, proper equipment – all in an effort to increase the bottom line. However, even if all other factors have been managed to perfection, if the optimal plant population is not achieved, yield and/or quality will not be achieved. Determining optimal plant population still requires some weather related assumptions – optimal plant stand for a dry season will be quite different than that of a wet season.

In an era of higher input prices, producers will try to cut back in areas they feel they can. Seeding rates may prove to be the area which would do the most damage to the bottom line – even more so than fertility levels. Kenton Possberg, Humboldt, Saskatchewan.

The cultivation of cereals arguably began some 8000 years ago and so it amazes me that in this modern day we have no concrete scientifically recommended seeding rates.

As a seed retailer the ‘What seeding rate should I use?’ is definitely one of the most common questions asked of us.

But low rates work too! As a seed grower, there are many times we plant at 25 to 30 pounds per acre with very little yield penalty to a fieldseeded with a normal (?) seeding rate. Often these low rates are for plot production where seed of new varieties can cost as much as $500 per acre but many times as well for field scale multiplication when seed availability is limited.

I believe an important factor for determining a seeding rate is one’s ability for precision seed placement (travelling slow and seeding shallow). This is not always practical or possible and so a suggestion to growers is, if they are happy with their past results then continue to do the same, otherwise select a desired plant population as recommended by research results and utilize a TKW rate calculator. John and Lisa Huvenaars, Hays, Alberta.

We have seen over the last few years a rise in seeding rates among our customers. Every year there are more people looking for 1000 kernel weights to help determine their
seeding rates. Generally rates have increased from 1.5bu/ac or 1.75bu/ac for barley to 2.0bu/ac and Hard Red Spring wheat from 1.5bu/ac to 2.0bu/ac. When we first started handling/seeding CPS wheat, a typical rate was in the 2.0bu/ac, now, many producers in our area are seeding at 2.5bu/ac. With the generally good rainfall in our area, the higher seeding  rates are paying off in higher yields. James and Peter Galloway, Fort Saskatchewan, Alberta. -end-