Crops
By Dr. Paul Tracy
Has early corn planting become the norm?
Until recently, the targeted corn planting dates for central Missouri were April 20 to May 15. Now, many of our producers want their corn planted by April 10. And that brings up some questions about shifts in cultural practice: Why early? Will it continue? What are the risks and rewards?
When planting early, all good agronomic practices like optimum seeding depth, proper hybrid selection, residue/weed management, soil moisture conditions, soil compaction and soil temperature (yes, we still prefer soil temperatures of 50+ degrees F) become increasingly important. Early seedlings will experience relatively harsh growing conditions and need all the help they can get.
Several factors have contributed to the adoption of earlier corn plantings throughout the Midwest. They are: a shift in weather patterns, improved genetics, advanced seed- treatment technologies, new equipment technologies, larger farming operations and the adoption of reduced tillage/strip tillage systems.
At a recent conference, Bill Wiebold and Patrick Guinan from the University of Missouri discussed corn planting date and weather interactions. Wiebold’s data showed corn emergence from early April plantings required 7 to 27 days. Corn emergence for mid-May plantings took approximately 5 days. These studies also showed a 10 percent corn stand reduction with early compared to late April plantings. However, when optimum plant populations were attained, yields were highest for corn planted in April and started declining as planting was delayed until May. Over the past 4 years, optimum planting time in terms of yield potential is almost 2 weeks earlier than what we recommended only 10 years ago. Similar trends have been documented throughout the Midwest/Midsouth with differing planting dates based upon latitude.
Physiologically, there are several reasons for corn’s response to early planting. With later plantings, there is less sunlight during the critical grain fill time period when kernel size is being determined. There are also fewer days of warmer temperatures after pollination for grain filling to be optimized.
Hopefully, with early plantings, enough heat units can be accumulated in April to June, that corn silking will occur before the hot-dry summer kicks into gear. Silking is the most important time during the growing season for corn to avoid stressed conditions. On average, corn planted about April 1 will silk around July 4, with May 15-planted corn silking around July 22. Are these 2 weeks enough to justify a 6-week jump in planting date? Over the past 30 years, central Missouri has received almost an inch of rain per week the month of July; however during the past 4 years, that average has decreased to about a half inch. This weather pattern, combined with warmer winters, drier early springs and wetter late springs, has led to greater interest in early planted corn. Are these semi-permanent weather patterns? Who knows, but many have adjusted their planting dates accordingly.
Improved genetics have played a vital role in allowing corn to be planted earlier. Over the last several years, I have observed corn emerge and then stay somewhat dormant through cool, wet periods and then explode as soils dry and warm. I did not notice this with older hybrids.
Seed treatment technology has improved greatly over the past few years. Early planted corn should have the best seed protection possible, including both disease and insect suppression products.
Early planting has also renewed interest in starter fertilizers and in-furrow insecticides. These products become increasingly important as cooler soil temperatures slow the plant’s ability to absorb nutrients and defend against pests.
No-till management is now mainstream and new equipment technologies like RTK have made strip tillage a very viable option. These practices have helped make early corn planting less risky.
Key benefits of early planted corn include:
• more days available to plant the entire crop
• time for replanting if necessary
• reduced risk of wet-weather planting delays
• more total days available to develop the crop through maturity
• earlier pollination may avoid hot-dry stressful conditions at silking
• crop maturity and dry-down will occur earlier in the season
• reduced grain drying costs
• potentially higher early season commodity prices
• greater storage availability
• tends to have a thicker stem-diameter-to-crop-height ratio, thus improving harvest standibility
Key risks with early planted corn include:
• a higher potential for reduced plant populations, uneven emergence and uneven stands
• increased potential for early season frost damage
• lengthy germination and emergence periods
• delayed root development
• extended period of susceptibility to seedling diseases and insects
If you plant corn early, consider the following:
1) Avoid planting excessive acres before soils reach 50 degrees F.
2) Avoid tilling or planting under compaction-prone wet soil conditions.
3) Plant hybrids with the highest emergence/seedling vigor ratings first.
4) Plant better drained south- or southwest-facing fields first.
5) Use the best possible disease/insect/nutrient seed enhancement program available including seed treatments, in-furrow insecticides and starter fertilizers.
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