Anhydrous Ammonia Effects on Soil Properties
By: John Woerner
Anhydrous ammonia is sometimes portrayed as being "bad for the soil." A common accusation is that NH3 makes the soil hard or "burns" up the organic matter. A long-term (10 year) study was conducted in Kansas to determine the effects of various nitrogen sources on several soil properties. Results from the study showed that there were no significant differences in soil bulk density (a measure of soil compaction) among N sources or between N sources and untreated plots. This was true whether bulk density was measured deep (deep enough to be under any old plow layer) or shallow. Also, the effect on soil pH and soil O.M. was similar for all three nitrogen sources compared. Applications of any of the N sources reduced soil pH when compared to the control. Nitrification of ammonium is an acid-forming reaction, and a pH drop is expected.
Soil organic matter content was not affected by the use of nitrogen fertilizers. There was no difference from the organic matter measured in the soil that had not received the nitrogen fertilizers. It is obvious that the anhydrous ammonia did not "burn up" the organic matter in the soil.
If applied properly, anhydrous ammonia continues to be an excellent source of nitrogen. There is not research to suggest that this product has a negative effect on soil properties.