The U.S. Drought Monitor Map and the Kansas Mesonet readings tell an interesting story this fall.
Typically, by the end of October, summer has faded and fall temperatures have settled in. But with just one widespread freeze the morning of Oct. 16, the state has recorded near-record to record-high temperatures in the 80s and 90s (degrees F) consistently. It's the fourth-warmest October in the recorded history of the state, and the warmest October in Kansas since 1963, according to Matthew Sittel, assistant state climatologist for Kansas.
That may be ideal for getting fall crops out of the fields, but it plays havoc with other chores, like spreading ammonia this fall.
Kansas State University Extension experts Dorivar Ruiz Diaz, nutrient management specialist; Bryan Rutter, K-State soil testing lab manager; Christopher "Chip" Redmond, Kansas Mesonet manager; and Peter Tomlinson, environmental quality specialist, go over some of the challenges of fall anhydrous ammonia applications in the Oct. 24 Agronomy eUpdate.
Fall applications of anhydrous ammonia appeal to producers who are trying to spread out their workloads ahead of corn planting in the spring, they explain. Depending on location, spring may be too wet to get into the field to apply that cheaper and more readily available anhydrous ammonia ahead of the planter, and instead opt for a more expensive option after planting.
Anhydrous ammonia needs water to react and convert into ammonium and adhere to clay and organic matter in the soil. But, that chemical reaction needs higher soil temperatures and wet soils to speed up the process. Otherwise, that ammonia just stays a gas that can escape through the large soil cracks left by drought.
For those farmers who plan to go forward and apply in dry soils, the team says it's best to follow these tips to reduce ammonia loss.
Apply it deep. Ammonia requires moisture for the chemical reaction, and that may be found deeper in the soil during dry conditions - at least 6 to 8 inches in 30- to 40-inch spacings. Producers can apply in dry conditions "as long as the ammonia is applied deep enough to reach some moisture and the soil is well-sealed above the injection slot," Diaz and Tomlinson write. "If the soil is dry and cloddy, there may be considerable losses of ammonia within just a few days of application if the soil is not well-sealed above the injection slot and/or the injection point is too shallow."
Seal the soil properly. Dry, cloddy soils with large air spaces can allow the gas to escape before it's converted to ammonium. Using covering disks behind knives or sealing wings on the knives can help.
Know your soil. Don't apply anhydrous ammonia in the fall on sandy soils. And on silt loam or heavier-textured soils, wait for soil temps at the 4-inch depth to hit 50 degrees or colder. Grass-covered soil at the 2-inch depth typically reaches 50 degrees around Nov. 20 in central Kansas, according to the K-State team. So, depending on the soil type, expect the 4-inch depth to lag behind that date, or be earlier if the ground is bare.
Use a nitrification inhibitor. Winter nitrification typically isn't a problem in Kansas, so long as application is done after the soil has cooled and a nitrification inhibitor has been used. But consider that soils warm up early in the spring, often well before corn planting starts. "Thus, one potential downside of fall application is that nitrification can begin in early March and essentially be complete by late May and June," the experts warn.
Read more:
https://www.vizda-industrial.com/nitrogen-fertilizer/ammonium-sulfate.html
