Thoughts from the field: Think twice before pushing soybean planting dates too early05/09/2017 |
By Matt Hoffman, ISA regional agronomist for northwest Iowa
Research has shown that planting soybeans early can increase yields. Some research has even suggested that planting soybeans early is CRITICAL to producing high yields. Provided suitable planting conditions, this all makes perfect sense. Longer growing season, increased canopy photosynthesis, longer reproductive growth, greater number of main stem nodes, more pods per plant, even the ability to select a fuller season variety. These are all potential benefits to planting earlier.
With all these benefits, why wouldn’t you want to get your beans in the ground as soon as possible? Sure, there is the risk of frost, freezing temperatures, increased seedling pest pressure if germination is slowed, etc.; but with all this spring rain (and more likely coming), let’s not forget about the extra soil compaction, specifically sidewall compaction, that can occur if you plant into wet soils.
Sidewall compaction occurs if the soil is too wet at planting. The planter’s opening discs will smear the sidewall of the furrow, which is further magnified by downward pressure of the trailing press wheel. This becomes a serious concern if dry weather follows planting and causes the soil to quickly dry and harden, preventing roots from penetrating the compacted furrow sidewall. This severely restricts root growth and consequently water and nutrient uptake, stand and overall plant vigor later in the season.
To my knowledge, there are not any options for alleviating sidewall compaction after planting. The best solution? Make sure your soils are dry enough BEFORE planting. Many are familiar with the “field test” or “ribbon test” for soil moisture. If you can form a ball or ribbon of soil in your hand without it partially crumbling apart, it’s too wet to plant.
I’m certainly not advocating against early planting dates. I’ve seen the research. My advice is to weigh all the factors, not just calendar date, and think twice about your soil conditions at planting, making certain you aren’t unintentionally putting your beans at a disadvantage.
Matt Hoffman is The Iowa Soybean Association On-Farm Network’s regional agronomist for northwest Iowa. To contact Matt about this article or available trial opportunities email him at firstname.lastname@example.org.
A version of this article was published in the May edition of Iowa Soybean Monthly.
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