Evaluation of the denitrification rate of terraced paddy fields
Onishi T. Nakamura K. Horino H. Adachi T. Mitsuno T. Journal of Hydrology (2012)
This study is particularly focused on the denitrification rate in terraced paddy fields.
To understand the hydrological properties of terraced paddy fields, a detailed water budget including the subsurface flow components was calculated. Combining the water budget components and chemical measurements of surface and subsurface water, a nitrogen budget was calculated. The results showed that about 10% of the total nitrogen input, mainly from fertilizers, was lost, suggesting the occurrence of denitrification in the area.
The average denitrification rate of the study site was estimated at about 0.53–0.67 g N m-2 year-1. Spatial variations in the measured groundwater nitrate concentration suggest that denitrification is important in both the plough layer and the sloping area.
The denitrification rate in the sloping area was estimated at 0.67–0.78 g N m-2 year-1, which is slightly higher than the estimates of denitrification rate in paddy lots, i.e., 0.56–0.61 g N m-2 year-1. The result indicates the importance of sloping areas for denitrification in terraced paddy fields.