Evaluation of Selected Processes Controlling Nitrogen Loss in a Flooded Soil1
- K. R. Reddy2,
- W. H. Patrick3 and
- R. E. Phillips4
The roles of NH4-N diffusion, NH4-N oxidation, NO3-N diffusion, and NO3-N reduction in controlling N loss from continuously flooded soil were evaluated in independent experiments. Applied NH4-N moved from zones of high NH4-N concentration to the zones of low NH4-N concentration. The average diffusion coefficient (D) for NH4-N in flooded soil ranged from 0.059 to 0.216 cm2 day−1 for different soils. Diffusion coefficients were influenced by soil type and soil-water content. Rate of NH4-N oxidation in the aerobic layer of flooded soil range from 1.2 to 3.5 µg g−1 day−1 in different soils. Nitrate diffusion into the anaerobic soil layer ranged from 0.96 to 1.91 cm2 day−1, whereas NO3-N reduction rates were 0.32 to 0.52 day−1. The slow rate of NH4-N diffusion from the anaerobic soil layer to the aerobic soil layer and the slow rate of NH4-N oxidation in the aerobic soil layer indicate that these two processes are limiting steps in controlling N loss. Nitrate diffusion into the anaerobic soil layer and NO3-N reduction in the anaerobic soil layer were found to proceed at a faster rate and are not likely to limit N loss from flooded soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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