"I have decided to buy a new seeder to start direct seeding but I am not sure on what row spacing I should buy." There has been a lot of talk the last couple of years moving to wider row spacing, most to 12" but some even as wide as 16". In conventional till row spacing was not a major concern because we did not have all the crop residue to manage at seeding. The first thing most producers are concerned about is yield.
Dr. Guy Lafond, at the Indian Head Research Station, was one of the first to look at the effect of row spacing in direct seeding. Previously most research was in conventional till systems. Lafond ran his study from 1989 - 1992 with spring wheat, durum, barley and flax. Row spacing were 4", 8" and 12".
Lafond found that yield of spring wheat was not affected by row spacing.(Figure 1) As row spacing increased, the number of plants established and the number of heads produced decreased. However, the number of kernels produced per spike increased as row spacing increased so that in the end, the different row spacing produced the same yield.
Durum had a superior yield at the 12" row spacing in each of the 4 years. Flax yields were not affected two of the four years but the 8" spacing was favored in the other two years.
Lafond states "Farmers should chose the row spacing that will give them the residue clearance they require for their equipment."
Figure 1
Lafond - Agriculture and Agri food Canada
Similar studies were done by Gordon Hultgreen of PAMI from 1993 - 95 with sites at Foam Lake, Unity and Naicam. At these sites wheat, canola and barley were direct seeded at 6", 8", 12"and 16" row spacing. Generally the yields decreased as rowspacing increased, however in some years at some sites yields were higher in the 16" row spacing. (Figure 2)
Hultgreen stated " The decrease in yield may be related to
weed competition. At wider row spacing the crop is less
competitive with weeds and it is likely the reduced grain yield
at wider row spacing is caused by weed competition." This shows
that weeds must be controlled and the yield reduction may not be
due to row spacing.
Figure 2
Hultgreen - PAMI
Other factors need to be considered
Yield is only one aspect that needs to be looked at when trying to decide on what row spacing to use. Other factors to consider are:
1) Soil disturbance - The wider the row spacing the less soil disturbance there will be.
2) Residue clearance - The wider the row spacing the greater the residue clearance and you will be able to cut your stubble taller without plugging problems next year.
3) Seed place fertilizer - If you are single shooting you can put less fertilizer with the seeds with wider row spacing.
4) Swathing - With wider row spacing 12" to 16" you must be prepared to straight combine most crops because swathing is only an option with canola.
5) Weed Control - spot spraying for weeds such as wild oats is much easier with wide rows because you can easily identify the weed between the rows.
6) Hp. required per ft. - Less horse power is required per foot of seeder with wider row spacing as you have fewer openers per foot.
7) Cost - The cost of a wider row spaced seeder will be less per foot as you are buying fewer openers, shanks and trips.
Today given these considerations many direct seeders are moving to 12" spacing and some even 16".
Bruce Barker, a direct seeder near Saskatoon converted his 8800 Bourgault air seeder to 16" row spacing with mid row banding anhydrous ammonia on 32" spacing in 1996. He used the Atom Jet knife and was very pleased with seed placement and row spacing but would like to try an opener that will give him a little wider seed row. Barker states " I grew the best crop ever this year."
If you would like to speak to direct seeders who have been seeding at wider row spacing phone our Direct Seeding hot line, at 1-800-213-4287, and we can put you in touch with them using our Farmer Helping Farmer data base.