As area farmers hit harvest hard while the weather remains temperate, officials with the Iowa Department of Agriculture and Land Stewardship along with the Iowa State University Extension and Outreach have a reminder for them. They want farmers to refrain from applying anhydrous ammonia fertilizer until soil temperatures remain below 50 degrees. By waiting for soil temperatures to drop, they can help reduce nitrogen loss and better protect the environment. Iowa Secretary of Agriculture, Bill Northey says it is also crucial to ensuring the fertilizer is available to crops next spring. Soil temperatures, like air temperatures, can change rapidly, he added, so it is important to wait with applications until they are likely to remain below that 50 degree threshold. John Sawyer, professor and extension specialist in soil fertility and nutrient management at Iowa State University said farmers should also make sure the soil is not too dry, too hard or too wet as those conditions can cause injection problems and allow ammonia to move through the soil surface and be lost to the air. He said if conditions are not suitable, then waiting for better conditions is suggested. ISU Extension and Outreach maintains a statewide, real-time soil temperature data map on their website that can be used to determine when fall nitrogen applications are appropriate. You can find that map by following this link. If you still have questions, contact your local ISU Extension and Outreach field specialist.
