Studies on some aspects of nitrogen in the soils of Columbia

A study of different methods for determining exchangeable and fixed ammonium (including acid extraction and alkaline distillation) was made on Colombian soils. This was followed by a study of the extent to which added ammonium was fixed artificially by the clay fraction extracted from Colombian soils, and the extent of nitrification of fixed ammonium during incubation of these clays. Nitrogen mineralization and nitrification and carbon dioxide evolution during incubation of the soils was studied at varying moisture levels, and the effects of addition of INao calcium carbonate and cellulose in these processes have also been determined. The two saline soils were acidified to varying degrees with three acidifying materials and nitrogen mineralization and nitrification and carbon dioxide evolution were determined in subsequent incubation with and without calcium carbonate addition. The effects of the length of air-dried storage of soils on subsequent mineralization of nitrogen and carbon dioxide evolution during incubation were studied. Studies were also made on factors affecting the extent of loss of ammonia by volatilization from Colombian soils.