Active Nitrogen Fixation by Iron-Reducing Bacteria in Rice Paddy Soil and Its Further Enhancement by Iron Application

In rice paddy soil, biological nitrogen fixation is important for sustaining soil fertility and growth. Anaeromyxobacter Geobacteriaceae, iron-reducing bacteria belonging to Deltaproteobacteria, are newly discovered nitrogen-fixing dominant in soils. They utilize acetate, a straw-derived major carbon compound as energy source, ferric iron compounds electron acceptors anaerobic respiration. our previous field experiments, significant increase activity was observed after the application of powder straw-returned soil. addition, combining with 60–80% conventional fertilizer rate could maintain yields similar those fertilization rate. It thus suggested that increased amount fixed by enhancing diazotrophic bacteria. The present study conducted directly verify this suggestion 15N-IRMS analysis combined 15N-DNA-stable isotope probing iron-applied no-iron-applied plot soils an experimental field. native atmospheric 15N2 incorporated into fixation, which were most active drivers fixation. 15N significantly higher due enhanced especially via bacteria, Thus, verified. This provided novel picture microorganisms dominated proved effectiveness enhance their incorporation enhancement fields may lead unique management strategies ensure reduced input lower environmental burdens.