Soybean Row Spacing in Kansas

May 03, 2022

There are still many questions about row spacing for soybean production. In this article we present a summary of recent research from K-State. From 2015 to 2017, a series of six On-Farm experiments were conducted across eastern and central Kansas (Figure 1).

For the 2015-16 seasons, four on-farm studies (collaboration between K-State, Kansas Soybean, and the United Soybean Board - USB) were conducted, one each in Franklin County, Hutchinson, Jefferson County, and Manhattan. For the 2017 season, two additional studies (collaboration between K-State, Kansas Soybeans, North Central Soybean Research Program) were conducted in Ashland Bottoms near Manhattan and Franklin County.

Figure 1. On-farm experiments on soybean row spacing comparing conventional (30-inch) vs. narrow rows (15-inch). Collaborators: Kansas State University, United Soybean Board, North Central Soybean Research Program.

Results summary

Compared to the conventional 30-inch row spacing, soybeans in narrow rows (15-inch or less) in these tests were likely to show equal or slightly greater yields (2-12%), particularly when the yield environment was less than than 50 bushels per acre (Figure 1) (regardless of planting date, seeding rate, or maturity). Above this yield threshold level, soybean did not show yield response to changing the row spacing (Figure 2). Overall, the common denominator of the response to row spacing is the inconsistency, denoted by the wide error of responses and by the variability between site-years.

Figure 2. Observed yield response in soybeans to narrow rows

Figure 2. Observed yield response in soybeans to narrow rows (15-inch) compared to conventional spacing (30-inch). Average yield of 30-inch strips is indicated on the left side of the figure (bu/a). At the lowest-yielding site, Manhattan in 2015, sovbeans in 15-inch row spacing had an average of about 6% higher yields than those in 30-inch rows. In the highest yield environments, Jefferson County in 2015 and Franklin County in 2017, there was very little yield difference between 15- and 30-inch rows. On-Farm Experiments (2015-2017). Collaborators: Kansas State University, United Soybean Board, North Central Soybean Research Program.

Final considerations

Some of the benefits of narrow row spacing:

Early canopy closure favors better light interception,
Improved weed control, and
Reduced potential for soil erosion.

On the other hand, some of the disadvantages of narrow rows:

Potential reductions in final stand at a given seeding rate, linked to equipment and within row compaction.
In very dry years, narrow row spacing may consume limited soil water earlier in the growing season, reducing the amount of water available for the critical period around pod-setting and seed filling.
In wet years, too narrow spacing (less than 15-inch) may allow less air flow within the canopy and favor the occurrence of certain diseases, such as white mold.

Source : ksu.edu

Video: Western Canadian Agriculture: Hard Times Made the World's Best Farmers

Western Canadian agriculture produced the most advanced farmers in the world not through abundance but through adversity. The crow rate fell. The wheat price went nowhere. The brown envelopes stopped.

When the subsidies disappeared, the bad farmers left and the good ones stayed. And the ones who stayed could not just grow wheat anymore. They started growing lentils and canola and peas and flax and faba beans. They built crop rotation. They got serious about agronomy because there was no government backstop. That process produced the Western Canadian agriculture Dennis Bulani describes in this clip: the most advanced, most educated farming culture in the world.

His contrast with Iowa corn and soybean farmers is sharp. At a DeKalb farmer meeting in Okoboji, Iowa, he asked what crop rotation they ran. Beans on corn stubble, corn on bean stubble. How do you fertilize? The co-op agronomist handles it. Have you considered other crops? No need. We make so much money on corn and soybeans. Western Canadian agriculture was never allowed that comfort. And now those Iowa farmers are watching soybean markets lock up with China and corn prices slide, and they do not have the agronomy knowledge or the research base to pivot. Western Canadian farmers adapted on a dime because they had done it before.

Dennis also makes the case that Western Canadian agriculture keeps adapting in real time. Low commodity prices over the past year have pushed growers to look seriously at precision spot-spray technology. He knows a neighbor who bought a sprayer with the seeing-eye system and sprayed only 80 out of 320 acres. As a chemical retailer Dennis acknowledges that will affect his sales. He supports it anyway, because if it advances Canadian agriculture and makes farmers money, that is a good outcome.

The lesson Dennis draws from the tale of two farms: continuous improvement is the only durable strategy. When canola was $22 a bushel some growers went to Arizona instead of the Crop Production Show. When the price came down those same growers came back to the research and the discipline. Products do not go on Rack Petroleum's shelves unless they pass a replicated trial first. That is what Western Canadian agriculture built through hard times: farmers who do the work whether the times demand it or not.

Dennis Bulani is CEO of Rack Petroleum and Ultimate Yield in Biggar, Saskatchewan. Dan Aberhart hosts GTF Productions, Western Canadian Agriculture's foremost live briefing platform and its foremost AI training platform for ag operators