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Nitrous Oxide Emission through Plants
Author(s) -
Chang C.,
Janzen H. H.,
Nakonechny E. M.,
Cho C. M.
Publication year - 1998
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/sssaj1998.03615995006200010005x
Subject(s) - shoot , canola , transpiration , nitrous oxide , hordeum vulgare , brassica , soil water , chemistry , saturation (graph theory) , horticulture , agronomy , environmental science , poaceae , soil science , biology , mathematics , combinatorics , biochemistry , photosynthesis , organic chemistry
Agricultural soils are a major source of N 2 O that has been linked to an enhanced greenhouse effect and the depletion of stratospheric ozone. The N 2 O produced in the soil is usually assumed to enter the atmosphere by diffusion. We postulated that significant amounts of N 2 O may also be emitted via plant transpiration, and conducted a controlled environment study to test this hypothesis. The shoots of canola ( Brassica napus L.) were enclosed in chambers, and N 2 O emission from the foliage was quantified by measuring changes in N 2 O concentration following various soil treatments. At field capacity, a treatment not conducive to denitrification, there was no measurable emission of N 2 O from the plant foliage. At saturation, however, N 2 O concentration within the shoot chamber increased consistently with time. By the end of the sampling period, the N 2 O concentration in the shoot chamber was 0.45 L L −1 , well above that in the soil head space (0.35 L L −1 ), demonstrating that N 2 O was released from the shoots and not the soil. Watering the soil with a N 2 O solution with a concentration of approximately 8 mL L −1 resulted in almost immediate release of N 2 O from the shoots, indicating that the N 2 O was not generated by the plants directly, but merely conveyed to the atmosphere by the transpiration stream. Experiments using barley ( Hordeum vulgare L.) produced results similar to those with canola, suggesting that emission of N 2 O from plants may be a common phenomenon. These results demonstrate a mechanism for N 2 O emission from upland crops, and imply that measurement of N 2 O release solely from the soil surface may underestimate actual fluxes from agroecosystems.