Over the last several years, there has been a shift to more soybeans being seeded with corn planters rather than with drills across the US Midwest and in Ontario. As planters get larger (and more expensive), many farmers have tried to make their planting more efficient and simple, usually by buying a wider planter that can plant both soybeans and corn. Some reasons for this include:

  1. More precise seeding rates and singulation (less controlled spilling)
  2. Savings in seed costs with wider rows – 140-150,000 seeds with 30” rows versus 190-200,000 seeds per acre with narrow row drilled beans
  3. More air movement in canopy to help reduce white mould pressure in areas
  4. Better seed placement and more uniform emergence with corn planter
  5. Sprayers can fit between rows, so less soybeans get tramped
  6. More fertilizer options at planting with pop-up seed placed fertilizer or banding next to the row
  7. One machine (farmers can plant all corn and soybeans with one planter, one man)

One disadvantage with going to wide rows is that there is generally a yield reduction. The University of Illinois conducted a 2 year study across the state and concluded that there was a 1.5 bu/ac yield drag associated with 30” rows compared to 15” rows. Horst Bohner, Soybean Specialist with OMAF, has been conducting row width studies over the years and has seen an even larger yield drag. His research suggests a 5.1 bu/ac yield disadvantage from 30” to both 15” and 7.5” rows on no-till. An interesting point with his research is that with fall moldboard worked ground, you can reduce this yield reduction to only 2.6 bu/ac compared with 15” rows and 3.9 bu/ac with 7.5” rows respectively.

The biggest reason for this is that the canopy takes longer to close. Bohner also says that “in order for soybeans to realize their maximum yield potential, 95% light interception should occur by early reproductive stage. It takes 14 days longer to fill the canopy in 30” rows compared to 15” rows.”

With planters getting larger, inter-plant units (for 15” rows) are making planters much heavier, requiring more horsepower. This is a reason some have opted to just stick with 30” rows when purchasing new equipment. If you are going to make the change, the key to getting the most out of wide rows is getting the canopy closed quickly.  Here are some ways to achieve this:

  1. Plant fuller season, bushy varieties that will get up and growing and fill in rows quicker
  2. Reduce residue in row, by either more tillage or more aggressive row cleaners on planter
  3. Plant as early as possible (if seeding with both a planter and drill, consider seeding the early ground with planter, and later ground with drill)
  4. More fertility (add fertilizer ahead of time on field, or apply with planter in band)
  5. Other foliar fertilizers applied in-crop to aid in vegetative growth
  6. Fungicides for white mould, or other leaf diseases (to make a healthier plant)

Chad Mangan, CCA-ON
Maizex Seeds District Sales Manager, Eastern Ontario