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Farmers Wait for Warmer Soil Temperatures

Farmers Wait for Warmer Soil Temperatures

AUBURN, Ala.—Warm air, sunshine and fields ready for planting make the warmer days of winter tempting for many row crop producers throughout the state. However tempting the weather, farmers know the importance of waiting for warmer soil temperatures before planting.

Brandon Dillard, an Alabama Extension agronomist, said cool soil temperatures are always difficult for farmers to deal with because as the ambient temperatures warm up, it feels like planting season. In the limbo of wait time, there are important considerations for farmers getting ready to plant.

Disadvantages of Planting in Cool Soils

“The first thing farmers should consider is the importance of uniform stands,” Dillard said. “In corn grown for grain, a uniform emergence is one of the most important aspects of high yields.”

Research has shown that a seed emerging as little as three days after the others will act as a weed and pull down the yield of neighboring plants. When a corn seed is planted in soils below 50°F, the seeds may absorb water, swell and rot.

Dillard said the second thing to consider when planting in cool soils is early growth. When a crop like corn, cotton or peanuts emerges from cool soil, the plants tend to grow slowly. While cotton and peanuts don’t have the direct correlation of non-uniform stands and lower yields like corn, they do have other issues.

“Cotton and peanuts planted in early cool soils struggle to outgrow the damage from early season insects, such as the western flower thrip,” he said. “This insect causes damage to leaves, slows plant growth and is a vector for tomato spotted wilt virus.”

Plants plagued with early season damage are not only slow to emerge, but also slowed by insect damage. Damage to the young plant can give weeds an advantage to outcompete the crop. For this reason, the maturity of crops planted two to three weeks after the first crop will be very similar in size.

Planting Dates Across Alabama

While it sounds easy enough to sit and plan in detail for the coming year, Dillard said delays in the field are inevitable. Whether it is planting dates, weed control, fertilizer applications or harvest, delays happen—especially if equipment is involved.

This year, late 2015 harvests and substantial rains in January and early February may already have a hold on planting dates throughout the state. Generally, the earliest plant times are for corn throughout the state. In South Alabama farmers plant corn from late February to early March. Followed by mid-March to late April planting in central Alabama, and late March to mid-May planting in the northernmost parts of the state.

Planting dates are important, but if weather warms up earlier and soil temperatures are right, Dillard said there is an easy way to test soil temperatures to know when to plant.

“Check the soil temperature with a meat thermometer pushed into the soil to the 2” depth,” he said. “By using that temperature and a good 7-10 day forecast, planting decisions based on soil temperatures can be made.”

Corn can be planted with soil temperatures of 55°F at a 2-inch depth, cotton at 65°F and 2-inch depth and peanuts at 65°F and 2 inches.

For more information about soil temperatures and planting times, visit www.aces.edu or contact your local Extension agent.



Featured image by shutterstock.com/PointImages.

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