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Direct Measurement of Dinitrogen and Nitrous Oxide Flux in Flooded Rice Fields
Author(s) -
Buresh R. J.,
Austin E. R.
Publication year - 1988
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1988.03615995005200030016x
Subject(s) - flux (metallurgy) , nitrous oxide , urea , nitrogen , chemistry , oryza sativa , zoology , transplanting , analytical chemistry (journal) , horticulture , environmental chemistry , biology , biochemistry , seedling , organic chemistry , gene
A direct 15 N method was used to measure N 2 and N 2 O flux in flooded rice ( Oryza sativa L.) fields. The method involved application of a highly 15 N‐enriched source to a 0.4‐m by 0.4‐m microplot, collection of evolved N 2 and N 2 O in a chamber placed over the flood‐water, removal of NH 3 from the air sample, conversion of some (N 2 + N 2 O)‐N in the air sample to NH + 4 ‐N, and determination of 15 N content with a mass spectrometer. The flux of (N 2 + N 2 O)‐ 15 N was measured for 17 d following urea application by three methods, each replicated four times, on a Vertic Tropaquept. In all cases, the (N 2 + N 2 O)‐ 15 N flux was much smaller than total gaseous 15 N loss as estimated from unaccounted for 15 N in the 15 N balance after 18 d. The (N 2 + N 2 O)‐ 15 N flux and total 15 N loss were 1.1 and 40%, respectively, following basal broadcast and incorporation of 58 kg urea‐N ha −1 with 2‐cm standing water; they decreased to 0.2 and 26%, respectively, when the urea basal incorporation was without standing water. The (N 2 + N 2 O)‐ 15 N flux and total 15 N loss were 0.5 and 46%, respectively, following application of 44 kg urea‐N ha −1 to 50‐mm floodwater at 10 d after transplanting. The methodology could detect a flux of 10 g N ha −1 d −1 from the added 59 to 64 atom % 15 N‐labeled urea. Additional studies with 15 N‐labeled NO ‐ 3 evaluated the possibility that the low (N 2 + N 2 O)‐ 15 N flux was due to incomplete recovery of N 2 and N 2 O formed from added fertilizer. Direct recovery of (N 2 + N 2 O)‐ 15 N following addition of labeled NO ‐ 3 ranged from 41 to 73% of the total 15 N loss. No 15 N was lost by leaching or runoff, and dissolved N 2 O in the floodwater calculated from published solubility data was less than 1% of the added 15 N.