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Soybean development concerns appear

Soybean development concerns appear
Scout's Report 2015: Will earlier, wet weather haunt the soybean crop during its critical stage?

This week's activities checking crops in the field focused on soybean development. As you well know, our soybean crop growth essentially "stood still" for much of June and July due to saturated soils and cooler temperatures in many parts of Indiana.

Scout's Report 8/19: Sudden Death Syndrome appears in Midwestern soybeans

Then about the last week of July, warmer temperatures and drier soil profiles allowed for rapid growth and development. Soybean height is shorter than normal. However plant development in my agronomic area in the northern half of Indiana is about on schedule with many fields being at the R5 (beginning seed fill) stage of growth.

Soybean in later stages: Here's a soybean in the R5 stage. It's about 1/8th final size. (Photo courtesy of Denny Cobb.)

R5 is an interesting stage of growth as maximum height, node number, and leaf area are established. Nitrogen fixation rates peak and then drop off in the late R5 stage of reproduction.  Root growth begins to slow. R5 is characterized by rapid seed growth and rapid filling of soybean pods. The demand for nutrients and water is very high.

About half the nutrients to produce and develop seed come from the soil and the other half comes from redistribution from soybean plant parts. Water deficiencies reduce nutrient availability because roots cannot take up nutrients or grow in upper soil areas where the soil dries out.

This is essentially a "make it or break it" time! This R5 stage is when timely August rains determine if you harvest an average crop or you harvest an exceptional soybean crop! This can be true no matter what happened earlier in the season, as long as the soybean crop survived and has now caught up.

Scout's Report 8/12: Ear tip filling, Northern corn leaf blight and Japanese Beetles in Indiana

The first half of August gave limited rainfall in most areas, with some of the areas that were so wet early, particularly in northwest Indiana, now getting too dry.

Let's hope that the last part of August is more conducive for seed fill!

Cobb is an agronomist for Beck's. He was one of the people who trained Christy Kettler, the Beck's intern who wrote this scouting report most of the summer. He writes from northern Indiana.

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