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Taking agriculture’s temperature
Dr. Victor Martin

The Drought Monitor shows thing essentially unchanged from the previous week. As of now the immediate area, except for the abnormally dry parts of Stafford and Rice Counties, are in good shape in terms of soil moisture for this spring. The six to ten day outlook (Feb. 12 to 16) has a 50 percent chance of above normal precipitation and below normal temperatures. Looking out eight to 14 days again indicates a slight chance for above normal precipitation and below normal temperatures. Normal highs should be in the mid-40ies for February. The 30 day outlook is for equal chances for above or below normal temperatures and precipitation with the 90 day outlook basically the same. Since weather weighs on the minds of crop and livestock producers, today let’s focus on temperature and its importance in crop production.

We normally think of moisture as critical for life and it is, however, temperature has the greatest effect on living organisms. It determines, along with moisture, what plants and animals are adapted to an area. Temperature, plays a critical role in pest control, especially insects and diseases. Seasonality of temperature helps define areas of plant adaptation. We live in a temperate climate with four distinct seasons. The key being an extended period of below freezing temperatures, winter, with an extended period of warm temperatures, summer. Other areas of further north are boreal where cool/cold temperatures predominate. Further south you experience only occasional freezing temperatures until eventually you reach tropical regions where temperatures are mild year-round. So what are the effects of temperature on crops?

• Winter wheat is a great place to start but here it’s cold that’s the key. Winter wheat, barley, and triticale will not flower unless they have accumulated a certain amount of cold. It varies by variety with some needing little cold and some a great deal. This insures the plant won’t flower until winter is past. Decreasing fall temperatures, along with decreasing daylight, help the plant enter winter dormancy. Flowering in the spring is keyed to two factors. Spring heat accumulation along with increasing day length key it to initiate the sequence involved in flowering.

• Corn development is driven by heat accumulation. Without describing the formula, it takes “X” amount of heat to germinate and emerge, so much for each leaf to emerge, for tasseling, silking, grain development and maturity. If you know this information, you know the growth stage of the crop without looking.

• Sorghums are similar, however, they also have the ability to essentially go into neutral when conditions for a period of time until conditions for flowering improve.

• The soybeans we plant here are a bit different in that while temperature helps drive development, flowering is initiated as day length decreases, and they flower in response to uninterrupted night length.

• Finally let’s not forget insects. For certain insects, their growth stage and development is similar to corn. You can predict their stage by monitoring temperature which is beneficial when monitoring the potential for insect problems.

• An added fact for home gardeners and producers – make sure to differentiate between air and soil temperature. Soils cool and warm more slowly than air temperature and are important when determining appropriate planting and seeding dates.

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