Anhydrous Ammonia Conversion

Anhydrous Ammonia Conversion

Figure 1. Reductions in nitrification over time based on temperature.
Figure 1. Reductions in nitrification over time based on temperature. (Source: Nutrient Management for Agronomic Crops in Nebraska, Nebraska Extension EC155)

In the 2018 growing season we experienced issues with anhydrous injury to newly planted corn. The environmental conditions allowing for this were different then what we are experiencing this year.

A significant percentage of anhydrous ammonia and UAN injection for the 2019 crop is occurring this spring. The conversion from ammonia to nitrate depends on soil temperature, soil moisture content, and time. Figure 1 illustrates this relationship.

Once in the nitrate state, germination and seedling injury is less of a concern. The other factor related to seedling injury is placement in relationship to the seed. The corn row should be 10 inches from the band of anhydrous ammonia applied shortly before or after planting.

Injected UAN also can cause injury as approximately 35% of a UAN solution is urea which too must convert to ammonium then to nitrate.