ABSTRACT
Soil air, particularly oxygen as its most important component, significantly affects biological and chemical transformations that occur in soil. Under anoxic conditions, caused for instance by soil submergence, changes in the microbial population are induced which bring about changes in the respiration of the soil, its enzyme activity, and redox potential. The consequence of oxygen deficiency in soil are variations of soil reaction and chemical transformations of many soil components, both organic and inorganic, leading to characteristic morphological features in the soil profile. Most of the processes contributing to the nitrogen pool in soil and to its chemical changes are related to the oxygen status of the soil. There are two kinds of microorganisms able to fix atmospheric nitrogen in the soil: the symbiotic and free-living nonsymbiotic. The soil oxygen status is connected with formation of some volatile organic compounds; the main ones being ethylene and methane.
