Popis: |
Employing gas chromatographic acetylene reduction assay, we investigated nitrogen fixation as influenced by alternate flooded and nonflooded conditions in two paddy soils amended with cellulose. The soil nitrogenase activity was higher under submerged conditions than under nonflooded conditions. The alternate flooded and nonflooded regimes resulted in alterations of the nitrogenase activity. Thus, nitrogenase activity increased several times following a shift from nonflooded to flooded conditions. In contrast, the nitrogenase activity decreased when the flooded soil was returned to the nonflooded condition by draining. Moreover, soil submergence favored nitrogen fixation irrespective of the length of the pretreatment under nonflooded conditions. |