Abstract
The influence of fertilizer and water management schedules on the nitrogenase activity associated with rice rhizosphere was investigated during the dry season in experimental plots at two sites. Field plots with a high percolation rate (8.0 mm day-1) and high sand (33%) content supported higher rhizosphere nitrogenase activity under continuous flooding than under intermittent flooding. Nitrogenase activity decreased marginally with an increase in the fertilizer N level. In field plots with a lower percolation rate (2.3 mm day-1) and lower sand (26%) content, intermittent flooding supported better nitrogenase activity than continuous flooding. The split application of N had little effect on the nitrogenase activity in this soil. Results suggest that, in addition to fertilizer level and water regime, soil percolation rate and sand content can affect the rhizosphere-associated nitrogenase activity.
