Northwest Iowa — Farmers who have completed their harvest may be getting anxious to get back in their fields to apply anhydrous ammonia, but they’re being urged to wait until soil temperatures are much colder.
John Sawyer is a professor and extension specialist in soil fertility and nutrient management at Iowa State University.
Sawyer says waiting for cooler soil temps before applying anhydrous ammonia in the fall will better protect the environment and ensure the fertilizer is available to the crop next spring.
He says ISU Extension and Outreach maintains a statewide soil temperature data map on their website that farmers can use to determine when fall applications are appropriate. It shows soil temperatures this week range from the upper 50s to the upper 60s across the state. The general recommendation for applying anhydrous ammonia is to wait until soil temps remain below 50 degrees.
In addition to waiting for cooler soil temperatures, farmers should also make sure that the soil is not too dry, too hard, or too wet. According to Sawyer, those conditions can cause injection issues and allow ammonia to move to the soil surface and be lost to the air.
The ISU Extension and Outreach Soil Temperature Data Map can be found by clicking here.