Concurrent observation of several processes of nitrogen metabolism in soil amended with organic materials

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Abstract
Under aerobic and anaerobic conditions, the concurrent ammonification, nitrification, denitrification, and N2 fixation activities in soils treated with several organic materials were determined. All activities were apparently observed only under aerobic conditions, particularly in the soils treated with organic materials with a low C/N ratio. In the case of a high C/N ratio, several processes were delayed due to the high activity of N immobilization, while under anaerobic conditions, the nitrification activity for the supply of NO3-N was so limited that the occurrence of denitrification was inhibited. The apparent ratio of nitrification to ammonification was higher under aerobic than anaerobic conditions. The ratio of nitrification to denitrification was also higher under aerobic than anaerobic conditions due to the complete inhibition of the nitrification process under anaerobic conditions. The ratio of denitrification to N2 fixation was higher under aerobic than anaerobic conditions. It was shown that it is difficult to predict the ratios of these processes only based on the soil C content or the C/N ratio of amended materials. These ratios are controlled by the C/N ratio of amended materials, as well as by the constituents of amended materials and the levels of NH4-N and NO3-N.