NATIVE CLAY-FIXED AMMONIUM CONTENT, AND THE FIXATION OF ADDED AMMONIUM OF SOME SOILS OF EASTERN CANADA

A study was made of the native clay-fixed NH4+ of some typical soils of Eastern Canada. Usually the amount of fixed NH4+ was related to the clay contents and increased down the profile but there were frequent exceptions to both of these generalizations. The amounts found ranged from 12 to 450 μg fixed NH4+–N/g soil. In general, with some cultivated soils, the cropped areas had lower native fixed NH4+ contents than areas that were in sod. The capacity to fix added NH4+ was usually low in the sandy soils and in general the B and C horizons fixed more NH4+ than the A horizons. For the soils that did fix NH4+, a larger amount but lower percentage was fixed as the amount of added NH4+ was increased. The amount of water in which the NH4+ was added had a slight effect on the percentage fixed, being a little lower as the amount of water was increased. The cultivated New Brunswick surface soils had low NH4+ fixing capacities. Analysis of the clay mineralogy of some soils showed a fairly close relationship between ...