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Inhibition experiments on nitrous oxide emission from paddy soils
Author(s) -
Xu Xingkai,
Boeckx Pascal,
Zhou Likai,
Van Cleemput Oswald
Publication year - 2002
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2001gb001397
Subject(s) - urea , nitrous oxide , paddy field , nitrification , agronomy , urease , amendment , nitrogen , chemistry , straw , soil water , soil ph , zoology , environmental science , biology , soil science , biochemistry , organic chemistry , political science , law
Rice fields using nitrogen‐based fertilizers play an important role in the global N 2 O budget. However, our knowledge is still limited with regard to the mechanisms affecting the N 2 O emission and to the measures that can reduce the emission. This paper reports a study of N 2 O emission from paddy soils. The effects of urea, hydroquinone (HQ, a urease inhibitor), and dicyandiamide (DCD, a nitrification inhibitor) have been studied in pot experiments with and without rice plants and with and without addition of wheat straw. With no wheat straw amendment, all treatments with inhibitors, especially with HQ + DCD, had a much smaller N 2 O emission during the rice growing period than the urea treatment, whereas a substantially increased N 2 O emission was observed from a rice‐free soil with inhibitors. The N 2 O emission from the rice‐planted soil was exponentially positive correlated with the NO 3 − ‐N concentration in the rice aboveground biomass. By comparing the total N 2 O emission from the rice‐free soil and from the rice‐planted soil, we found that urea application alone might induce an apparent plant‐mediated N 2 O emission, being 0.39 ± 0.08% of the applied urea N. Wheat straw incorporated into the flooded surface layer soil could increase the plant‐mediated N 2 O emission significantly. However, application of HQ + DCD could reduce this emission (0.27 ± 0.08% of the applied urea N, compared with 0.89 ± 0.18% in the urea treatment). It also reduced the N 2 O emission from the rice‐free soil and from the rice‐planted soil. Stepwise regression analysis indicates that denitrification in the flooded surface layer soil was the main source of N 2 O emission from this wetland rice cultivation, particularly when wheat straw was added. A significantly nonlinear negative relation was found between the N 2 O emission and the CH 4 emission when no wheat straw was added, but it was hard to quantify this trade‐off relation when wheat straw was incorporated into the flooded surface layer soil.