Some Aspects of Ammonia Sorption by Soil Surfaces

Abstract

AbstractRates of sorption of NH3 through soil surface boundaries, the extent of penetration into thin surface strata, and relative sorbing capacities of surface layers were determined for soil materials from several Coastal Plain and Piedmont soils. NH3 sorption through soil surface boundaries was rapid from aerial applications ranging from 1.3 to 1.9 mg. NH3‐N per cm.2 of surface area. Specific rate of sorption was directly proportional to the concentration of NH3 remaining above the soil surface. NH3 nitrogen sorbed by soil in the surface strata did not penetrate more than 10–20 mm. into the soil when applied at rates ranging from 0.17 to 1.00 mg. NH3‐N per cm.2 of surface. The depth distribution of NH3 changed with time of contact with NH3 without appreciable change in total NH3 sorbed. In general clay soils sorb more efficiently than sandy soils, soils with low pH more efficiently than those with high pH, and soils with high organic matter contents were less efficient than mineral soils with similar cation‐exchange capacities.