By Grant Mehring,NDCUC Contracted Research Director

What is the earliest and latest you have ever planted corn on your farm, or that producers that you work with have planted? I encourage you to think about this as plant 2017 nears. Planting dates in corn production are critical for reaching maximum yield and optimum harvest moisture of a corn crop. Given that corn is a heat and growing degree day driven crop, it makes sense that planting date can have such an impact on yield and moisture. I want to cover a few things relating to planting date as field season nears.

The first thing to discuss is current soil temperatures. Interim Director of the North Dakota Agricultural Weather Network, Daryl Ritchison, had an outstanding tweet this morning illustrating where the frost line is at across North Dakota.

Any location or depth that has blue text and a 0 C or below indicator means there is still frost at that depth. You can see that it is variable, however even in the heart of corn country at the Wyndmere, ND, station there is still frost from 16-24 inches deep. As this frost comes out and our soils warm, they may get wetter again before they start drying. Be sure to use NDAWN 4 inch soil temperatures and any other sources of soil temperature information to make the call about initiating planting.

The next question to answer is what are ideal soil temperatures for planting corn? The general rule is 50 F at the 2-4 inch soil depth. At 50 F corn will germinate and begin growing when there is adequate soil moisture. The worry if your daily soil temperature cycling dips below 50 F is that your newly planted corn seed could imbibe it’s first drink of cold water below 50 F soil temperatures, and not successfully germinate. This is called imbibitional chilling and it is a real concern when planting too cold, or if temperatures turn cold soon after planting. Imbibitional chilling from seeding at too cold of soil temperatures will at worst cause seed death and poor stands, and at the least cause irregular germination synchronization where corn plants are at different growth stages in the same field.

The final consideration as to planting date is final yield and moisture of the harvested crop. Planting dates on both the early and late side of the planting window have their respective risks. Early planted corn has the risk of an April/May frost that could set the crop back and cool soil temperatures that could lead to problems talked about earlier. Whereas late planted corn might not reach physiological maturity before a killing fall frost, and could be too wet for an economical harvest. Generally, the optimum planting date for corn in all regions of ND is May 1st, however recommended relative maturity hybrids to plant varies by region. There have been some yield trials in ND with planting date as a factor to draw inferences from. Some planting date data I have access to from small plot research in Cass County from 2016 showed identical yields of two different hybrids whether they were planted May 1st or May 20th. Some past data from SE ND indicated that corn planted before May 20th would have minimal yield losses due to planting date. However, corn planted in June tended to lose between 1.1 and 3.0 bushels/acre per day of delay. The yield losses would largely be due to heat units accumulated during the summer.

In conclusion, I want you to pay special attention to soil temperatures and planting dates as plant 2017 nears. There are many factors to consider for reaching maximum yield and optimum moisture of your planted corn. If you can avoid the issues associated with both early and late planting of corn, you will be setting yourself up for an excellent 2017 growing season.