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Consider Corn & Soybean Strategies

University of Minnesota Extension, Stearns County News
May 7, 2014         
Source:  Dan Martens, Extension Educator
University of Minnesota Extension
Stearns, Benton & Morrison Counties


Consider Corn & Soybean Strategies
By Dan Martens, University of Minnesota Extension

FOLEY, Minn. (05/02/2014)
Jeff Coulter, U of M Extension corn specialist, shared some information related to weather conditions and corn planting prospects.

Several U of M studies from 1988 to 2003 and from 2009 to 2011 - including sites at Lamberton, Morris, and Waseca found that corn yields averaged 92 to 95% of the maximum when planting occurred by May 20. These studies were funded by the Minnesota Corn Growers Association.

Yield advantages associated with early planting typically are greatest when there is warm weather and rapid growing degree day accumulation between earlier and later planting date opportunities. Given the limited growing degree days that have accumulated since April 21, there probably wouldn’t be much difference between planting the last week of April and the middle of May this year. That’s probably usually the case when spring stays wet and cold from early on.

Coulter also writes, “Although timely planting is important, it is equally important to avoid tillage and planting when soils are too wet. In general, a field is fit for seedbed preparation when soil at tillage depths crumbles when pressed together rather than forming a ball.

Sidewall smearing can occur when double-disc openers cut through wet fine-textured soil, resulting in compacted soil around the seed that is difficult for nodal roots to penetrate. In addition, seed furrows can open up, after fine-textured soil dries following wet conditions at planting, resulting in poor seed-to-soil contact and poor stand establishment.

We also know that sometimes we don’t get ideal planting conditions and we have to do the best we can with what we get. Coulter says that, a general guideline for growers in Minnesota is to stick with the planned full season hybrids until around May 21-25 based on optimal yields and returns. The grain might be a couple points wetter in the fall; but the yield counts in most cases.  

Coulter’s article can be found by doing a website search for Minnesota Extension Crop News or by calling our County Extension Office. If things get later, like they did last year, he gives guidelines for shifting to earlier varieties at some point. This isn’t a new situation to be in, in our part of Minnesota; and your past experience and common sense about things counts a lot.

Seth Naeve, U of M Extension soybean specialist offered the following comments. We’re probably not planting soybeans anytime soon. But rainy weather might give us more time to consider strategies as we see how spring unfolds.

  1. Select and plant only the best varieties:  Not all soybeans are equal.  Each year, seed companies sell soybean seed with a wide range in yield potential.  Typically, the best-yielding varieties produce between 20 percent and 40 percent greater yields than those at the bottom.  Don’t get stuck with a dog. Make your initial selections carefully by using third-party yield information, and only accept substitutions with proven yield potential.
  2. Correct low-testing soils now:  Carefully evaluate soil test results.  Soybeans can typically utilize residual phosphorous and potassium from a well-fertilized previous corn crop, but if you're unsure about fertility levels, conduct a soil test in the spring.  Once planted, it's too late to fix deficiencies.  Despite renewed attention to this old topic, do not apply nitrogen to soybeans.  Nitrogen very rarely increases soybean yields - not to mention extremely rare economic returns.
  3. Plant early:  Although delayed planting is likely in most areas, plant as early as possible -- but only into good soil conditions. Avoid planting with extreme cold and wet weather in the near-term forecast or in extremely dry soils.
  4. Plant in narrow rows:  Soybeans planted in narrow rows will out-yield those planted in 30-inch rows or wider.  You can expect approximately 5 percent of yield advantage for every 10 inches of narrowing, down to about 10 inches.  Fields with a history of white mold may still be planted in narrow rows, but populations should be managed carefully.
  5. Don't trust a post-emergence-only herbicide program:  Including pre-emergence herbicides into an overall weed-management strategy provides a wider window for mid-season applications and allows more options for weed control.  Reduce short- and long-term risks by using herbicides with diverse modes of action.
  6. Be Safe:  The springtime rush often brings long working hours.  Please avoid taking additional risks wherever possible.



Daniel Martens
Extension Educator, Ag Production Systems
(320) 968-5077
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