April 24, 2017 Quick Look at Area Soil Temperatures and Successful Planting of Sorghum, Corn, & Cotton
Planting season is nearly upon us again, and many good producers are getting very antsy about getting into the field, especially our sorghum producers who need to get that crop started and get as much development completed as possible before the dreaded sugarcane aphid arrives. This morning I took two soil temperature readings in Southern and Southeastern Swisher County. The first was 59°F and in a no-till pivot with heavy wheat stubble cover. The second was at 60⁰F and in conventionally flat tilled, drip irrigated cotton on cotton ground. This is a pretty good soil temperature for planting corn or grain sorghum, but is far too cool for cotton. Then there is the consideration of this week’s forecast with two additional cold fronts due in before the start of May with night temperatures dipping into the 30’s and 40’s.
The minimum soil temperature for corn is 56°F (preferably 58°F or with a warmer week ahead to emerge into) while sorghum requires a 58°F (preferably 60°F or with a warmer week ahead to emerge into). With those cooler temperatures in the upcoming forecast I do get a touch apprehensive about all crops we might have starting in the soil so far, but odd remain that corn and sorghum should be ok as just as many warm days are predicted as cold.
Cotton gets off to its best start when planted in a recommended 69°F consistent temperature soil (roughly 64°F bare minimum with high air temperatures in the upper 80’s to low 90’s for the following week to continue a steep soil warming trend). Soil temperature can and does generally follow air temperatures with some lag time. Higher moisture content in the soil usually slows the soil’s response to air temperatures while dryer soils respond quicker. Likewise, soils with heavy cover will naturally be cooler through the shading of the soil by the cover. The best time to take soil temperature reading in your fields would be between 7 AM and 10 AM. That early morning period is when the soil temperature should be at its lowest, guaranteeing that the reading is accurately the minimum temperature we need to be watching. As I look at the forecast, jumble it up with research results about cotton getting off to its best start, the cotton should certainly stay in the barn for a bit longer.
We will be taking a few more local soil temperature readings next week to get the best feel for ideal cotton planting conditions.