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Cold, cold soil?
vic martin mug.tif

First a very Happy Easter to all and also enjoy April Fools’ Day. Today is April first which means a great deal should be happening in the cropping world in our area. One of those happenings should be wheat jointing before now but with the dry and overall cool conditions that is behind. It is likely farmers won’t have a great deal of straw to deal with this year. Alfalfa is greening up but overall lagging in growth to most recent years but that isn’t necessarily a bad thing. Many recent years the alfalfa was up and growing early due to warm temperatures which unfortunately also had alfalfa insect pests out and about. It is normal to expect to have to spray for these pests at least once before the first cutting which is normally the largest cutting for many in terms of tonnage. However, the last few years it has been difficult to bring in the first cutting due to insect pressure and not uncommon for many producers to spray several times and still have trouble. The reason has been that while the insect pests have come on early, the parasitic and predatory insects haven’t. That combined with less effective insecticide options has created a problem. Now unto today’s topic – soil temperature.
Spring planted crops such a corn, soybeans, and grain sorghum need minimum soil temperatures to germinate, emerge and grow vigorously. That minimum is not the ideal temperature but one at which the seed can take in water, have the seed germinate, send out the radicle (seed root) and shoot (cotyledons for soybeans, and coleoptile for corn and grain sorghum). Each crop has a minimum and an ideal temperature. Lower for corn and higher for soybeans and milo. The K-State Mesonet soil temperatures at 2 inches south of St. John from March 22nd through the 29th shows an average temperature of 52 degrees, a low of 43 and a high of 68. For Hays the average was 46, the low 44 and the high 49. These are temperatures under grass covered soil so barer soil should be warmer as is drier soil. The Hays area is naturally a bit cooler than Stafford County. So is the soil too cold to plant corn?
First, the recommendation locally is approximately April 10 for dryland corn and mid-April for irrigated of course depending on conditions. As long as two inch soil temperatures are fifty degrees or above, good uniform germination should result and take about a week with adequate soil moisture. If temperatures dip much, a non-uniform stand may result but with seed treatments, insects and diseases shouldn’t be a huge problem. To be safe, it is best for soil minimums to stay above fifty. So the short answer is that unless things change dramatically, soil temperature shouldn’t delay corn planting.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.