Should I plant corn?
Corn planting is delayed in central North Dakota this year due to cold air and soil temperatures. The current May forecast is for more clouds than sunshine, high temperatures in the mid-60’s and lows in the mid-40’s, and little rainfall. This forecast makes it difficult to know when to plant corn. Top soil moisture is being depleted in most of the region as we continue to wait for warmer soil temperatures.
Fields in the area are becoming dry enough to plant now, so should corn be planted now based upon soil temperature or soil moisture? Corn will not germinate until the soil temperature at the seed reaches 50 degrees Fahrenheit for a few days. As of May 5, the 4-inch bare soil temperature at the Carrington Research Extension Center was only 41 degrees Fahrenheit! Too cold to germinate corn.
Uneven emergence in corn can decrease yields by five to nine percent. Planting corn in optimum soil temperatures for quick emergence and planting in optimum soil moisture is critical for uniform corn emergence and eventually yield. Purdue University research reported corn planted in soil with a 4-inch soil temperature of 65 degrees emerged in seven days compared to daily average soil temperatures of 55 degrees Fahrenheit taking up to 23 days to emerge.
Based upon current soil temperatures, it is not best to plant corn yet, however if we wait and there is no soil moisture present to germinate corn, it will not emerge then, either.
The optimum corn planting window in North Dakota is up to May 20; after that yields usually decline and an earlier-maturing corn hybrid should be considered to ensure corn reaches maturity and the corn is drier at harvest. Based upon the soil temperature, corn planting should be delayed; however, corn also needs to be planted into adequate moisture for germination and emergence. Based upon the current forecast rain chances are minimal. Therefore, as long as the soil is not too wet, corn planting may need to start now regardless of soil temperature, but risk is involved with this decision.
To ensure uniform corn emergence when topsoil moisture is depleted, plant corn two to three inches deep, where the moisture is. Planting deep will take longer to emerge, but planting in soil that is too dry won’t allow the corn to germinate and emerge at all. With soil temperatures forecasted to be cool and with soils likely not to be saturated based upon the current rainfall forecast, planting corn deep should not cause much of a negative impact. The only potential is for soil crusting if it rains, but again that is not in the forecast. Applying a good seed treatment to protect the corn is necessary under these conditions.
Based upon the current dry forecast, plant as quickly as possible after tillage to maintain maximum soil moisture around the seed for uniform emergence. Tilling fields to “dry them out” and waiting several days before planting likely will dry the soil too much.
In summary, don’t plant corn until the soil has dried enough to make a good seedbed. If the soil is dry, plant corn while there is still moisture for germination. Try to wait until soil temperatures are above 50 degrees Fahrenheit for several days.
Planting corn into good moisture knowing corn emergence will be slow and potentially uneven due to cool soil temperatures is more important than waiting and not having the moisture to provide good emergence. If irrigation is an option, delay corn planting for warmer soil temperatures.
Jeff Stachler, Ph. D., CCA
Jeff.Stachler@ndsu.edu
Extension Cropping Systems Specialist
