ISSN:
1573-0867
Keywords:
15N balance
;
nitrification
;
denitrification
;
NH3 loss
;
flooded soils
;
windspeed
;
temperature
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The contribution of NH3 volatilization to the total N loss after the application of urea to flooded rice fields was evaluated in a series of experiments at two locations in the Philippines. Urea was applied in three ways: A. Broadcast and surface incorporated before transplanting (BI treatments), or B. Broadcast into the floodwater 14–21 days after transplanting (AT treatments), or C. Broadcast into the floodwater 5–7 days before panicle initiation (PI treatments). Total N loss was determined by using15N balance methods on microplots within fields where NH3 loss was measured concurrently by a direct, nondisturbing technique. The total15N losses in the AT studies at the completion of the NH3 loss measurements at Muñoz and Los Baños accounted for 45 and 60% of the15N applied, respectively. Ammonia volatilization accounted for all of the15N lost in the Muñoz study but only 45% of that lost at Los Baños. In comparison with the AT studies, lower N losses (18–26% of N applied) were obtained in the BI treatments. At Los Baños, NH3 loss again accounted for about half of this N loss. In the PI study at Muñoz, NH3 loss and total N loss accounted for 11 and 13% of the N applied, respectively. Thus, NH3 volatilization appeared to be the only important loss mechanism at Muñoz. In contrast, loss by an alternative mechanism, most probably involving nitrification-denitrification, was of equal importance to NH3 volatilization at Los Baños. Differences in windspeeds, temperatures, and soil properties at the two sites may account for the variation in the relative importance of the two N loss mechanisms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01048620
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