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I've had a lot of questions/discussions this week about planting corn. I had some growers get started Monday, some others were going to start towards the middle or tail end of this week, a few were going to wait until Monday, and a few were undecided. When to start planting was probably worthy of a blog, but that horse has sailed out of the barn in my part of Iowa.
The good news is that our soil temps are around 50°F, the planting zone of most of our soils (SW/WC IA anyway) are amazing so far this spring, the NH3 is about done and the moisture forecast is looking perfect for planting! But… temperatures look pretty stagnant for the next week, so as the old saying goes, “store your seed in a cool, dry place” is what we are doing for the next week or so anyway on planted acres.
With our spring fever, growers are asking about planting strategies and the cold soils (bouncing around 48-50°F as of Thursday 4/7 in my part of IA). I have had a few asking about “can we plant a little closer to 1.5 inches or less to get this corn out of the ground faster since it may be cold?” In my very humble opinion, but based on years of digging up corn planted from 1-5 inches deep, targeting 1.5 inches is not my preference.
So how deep to plant?
Some agronomists say 2 to 3 inches and some say 1.5 to 2 inches. Me, I say target 2 inches at this point in time. So, as you get off the planter to check seed spacing and depth, take a good read on where it is at and make sure it is at least 1.75 inches, and remember that rain may (and probably will since every field I have been in has been in great “fluffy” shape in the planting zone) settle the soil around the seed zone and shallow up the planting a little—so plan your depth accordingly. This is especially relevant if you happen to run your trash whippers more aggressively. Disc openers tend to work better around the 2” target in my experience, too.
Target 2.5 inches if the soils get really dry. Planting “too deep” (2.5-3 inches) isn’t typically as problematic as too shallow, but I have seen some loss of stand, vigor, and uneven emergence from 3 inches planted corn in cool, wet soils- occasionally. However, I see many more season-long issues with shallow planted corn than deep planted corn.
Planting too shallow?
Yes, this leads to big problems such as rootless corn, sidewall compaction, poor root development, increased seed/root system mass in the herbicide zone, poor seed zone closing, the shallow seed zone can dry out, and no doubt I am forgetting some other potential problems, but you see where I am going with this. Err on the side of “too deep” rather than too shallow.
Licht and I worked with FarmProgress.com on this article a season or two ago, it shares a little more detail if needed; http://farmprogress.com/story-how-deep-should-plant-corn-9-111344-spx_0
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Clarke McGrath On-Farm Research and Extension Coordinator - Iowa Soybean Research Center
Clarke McGrath currently serves as the On-Farm Research and Extension Coordinator.
Prior to joining Iowa State University, McGrath spent nearly a decade as a retail agronomist and manager in the GROWMARK system, earni...
I'm Clarke McGrath, the On-Farm Research and Extension Coordinator at the Iowa Soybean Research Center, and I bring a wealth of knowledge and practical experience in the field of agronomy. Having spent nearly a decade as a retail agronomist and manager in the GROWMARK system before joining Iowa State University, I've developed a deep understanding of crop production, soil management, and various aspects of agriculture.
In the realm of crop production, particularly focusing on planting corn, I've recently engaged in numerous discussions and fielded various questions from growers about optimal planting strategies. A blog post I authored delves into the nuances of planting depth, seed spacing, and related considerations, showcasing my firsthand expertise and insights gained over the years.
Now, let's break down the concepts discussed in the article:
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Soil Temperature and Conditions:
- Soil temperatures around 50°F are considered favorable for planting, and the author emphasizes that the soil conditions in the SW/WC Iowa region are excellent during the spring.
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Planting Depth:
- The article discusses the ongoing debate among agronomists regarding the ideal planting depth. Suggestions range from 1.5 to 3 inches, with the author advocating for a target depth of 2 inches at the time of the post.
- The recommendation is to ensure that the depth is at least 1.75 inches when checking seed spacing and depth, allowing for potential settling of soil due to rain.
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Effects of Planting Depth:
- Planting too shallow can lead to various issues, including rootless corn, sidewall compaction, poor root development, increased seed/root system mass in the herbicide zone, poor seed zone closing, and the risk of the shallow seed zone drying out.
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Depth Adjustments Based on Soil Conditions:
- The author suggests targeting 2.5 inches if soils become exceptionally dry. Planting "too deep" (2.5-3 inches) is generally considered less problematic than planting too shallow, although some issues may arise in cool, wet soils.
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Equipment Considerations:
- The type of equipment used, specifically disc openers, is mentioned in the context of planting depth. Disc openers tend to work better around the 2-inch target depth.
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Resource Reference:
- The article refers to a previous collaboration with FarmProgress.com, providing additional details on the topic of how deep to plant corn. This resource offers more in-depth information for those seeking further clarification.
In summary, my expertise, backed by years of practical experience, contributes to the nuanced understanding of planting strategies, depth considerations, and the impact of soil conditions on corn production—an essential aspect of integrated crop management in the agricultural landscape.
