The Effect of Anhydrous Ammonia on Water Stability of Soil Aggregates

Abstract

The effect of anhydrous ammonia (NH3) on the water stability of soil aggregates was investigated from 1954 to 1957 in the field and laboratory. Ammonia was applied with a commercial applicator to corn in field plots. Soil aggregates from some of these plots were treated in the laboratory by a procedure for NH3 application set up to reproduce as nearly as possible conditions in the field along the applicator path. In field experiments conducted in 1954 there was a trend toward an increase in soil aggregate stability as a result of NH3 treatment at 23 locations in Maryland. Soil samples from the check plots of these locations increased greatly in stability when treated with NH3 in the laboratory. These increases were correlated with the total organic matter content (r = 0.661, n = 14). The increase in soil aggregate stability due to NH3 treatment was not as large from 1955 to 1957 as in 1954. The difference in the effect of NH3 on soil aggregate stability between 1954 and 1955 to 1957 suggested that the increase in aggregate stability was related to a specific, although not identified, fraction of the organic matter rather than total organic matter. An explanation of the effects of NH3 on soil aggregate stability is proposed.