What Causes Uneven Emergence?

Planting season this year was a race to the fields over fear of repeating a season like 2019. Fast forward through a decent planting season – the corn and soybeans began to emerge and share the story on how the planter performed and if the practices we implemented were successful. Some fields appear outstanding while others are visibly lacking. So, what do we do about this? What did we do differently in the fields that are performing optimally? Then we ask, what did we do in the fields that are under-performing?

My commute allows me plenty of windshield time, which I spend analyzing the fields. The biggest commonality of most fields I see is the unevenness. It makes me wonder, what is causing this to occur? I bet you are curious, too.

Let’s dive deeper into the subject of uneven emergence – what causes it? Soil conditions were close to fit when we started planting this year and we knew if we put seed in the ground in the early part of the week, by the end the ground would be perfect. We are pushing the envelope more than ever with planting conditions and earlier start dates. If we fail to plant in optimal conditions, we know that our yields are likely to suffer. This year, soils were moist during the early part of April but by month’s end, had dried out considerably. For most Iowa farmers, this is an optimal soil condition, but is this what the seed needs? When we study uneven emergence, one of the most common causes is dry soils. Soil moisture issues can be caused by soil type, topography, or tillage practices implemented in the field. Cloddy seedbeds caused by tillage can result in poor seed-to-soil contact, which could be caused by high speeds during tillage, or the variability of the soil moisture. Corn may also emerge unevenly due to herbicide injury, insects, and soil crusting.

Soil temperature can also be blamed for uneven emergence. As we move planting start dates earlier, temperatures are colder which can cause the seed to germinate late. We noted that soybeans planted in late-May were subjected to a late-season frost and many of these fields showed signs of poor emergence because of that.

Sometimes, uneven corn emergence comes from replant when we fill in the spots that did not grow or resulted from water damage from the first pass. Which normally, depending on the weather, can cause drastic differences in stages.

It’s safe to say that uneven corn emergence affects yield, but what the yields in 2020 will bring is yet to be determined. Looking at the cause of uneven emergence is a great place to start. We can also look at data from prior years where we saw uneven emergence and that can give us a good idea of what we may see this year. We know Mother Nature is in control, but there are several management practices we can implement for next spring  that can increase our stand and our yields. – TJ Schott           

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Posted on August 4, 2020 in