News

Little Space, Big Bottom-line Difference


A little space could make a big difference for some Iowa farmers. As planting begins, switching to narrow row spacing is a simple change that could potentially add some cushion to farmers’ bottom line.

“The idea of planting soybeans in narrower rows is not a new concept,” said Brett McArtor, Iowa Soybean Association On-Farm Network field research specialist for southern Iowa. “From research we have conducted and analyzed, narrowing soybean row spacing is probably one of the more consistent practices a farmer can do to increase soybean yields.”

Research comparing 15-inch row spacing versus 30-inch is being conducted for the third year in a row across Iowa with the On-Farm Network, and across the country through a project with the United Soybean Board. Nine states participated in the research last year and more are expected to this year. There are both pros and cons for planting narrow rows.

Pros

  • Much earlier canopy closure – reduces weed pressure and soil moisture loss
  • Increased sunlight interception – increases growth rate, dry matter accumulation and seed yield
  • Easier harvest – Narrow row soybeans can be harvested more efficiently

Cons

  • Pest problems – narrow rows may cause more severe infestations of diseases like white mold
  • Crop damage – Wheel traffic damage from late season pesticide applications
  • Cost – upgrading to a narrow row planter is a big investment, as is having multiple planters for multiples crops

Checkoff-funded research at Iowa State University showed a 4.5 bu/Ac advantage to 15-inch row spacing compared to 30-inch spacing. On-Farm Network research, compiled with United Soybean Research in nine states have also showed a positive response to narrow rows, but not to the same extent.

This spring the On-Farm Network, funded by Stine Seed, is looking to set up additional sites across the state to compare row spacing yields across a three year period. The extended time frame will allow researchers to analyze the row spacing differences under the influences of different weather patterns and management practices.

There are a couple ways farmers can set up a row spacing trial. For farmers with a 30-inch planter, they can plant the field in 30-inch sections as normal, and then go back through the field a second time planting replicated strips of 15-inch spacing. In this case the seeding rate is reduced by half for each trip. For farmers with a 15-inch planter, they can turn off rows to mimic a 30-inch planter in replicated strips. This type of trial is possible due to increased GPS accuracy in most tractors.

“Row spacing trials are easy to set-up, and harvest is a breeze because you can visually see where the treatments are,” McArtor said. “Farmers who receive yield and scouting results from our analysis find them really useful to predict a return-on-investment, but also to predict in-season weed and disease pressures. At the end of the day it comes down to determining if narrow rows can work on your operation.”

At harvest, soybeans have to be harvested with the row, for these trials, rather than on an angle. Other equipment and methods can also work, depending on a farmer’s personal management techniques. The On-Farm Network can work with farmers to determine what will work best for their operation.

Source: Allie Arp, Iowa Soybean Association

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