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DENITRIFICATION IN A VERY ACID TROPICAL SOIL
Author(s) -
WICKRAMASINGHE K. N.,
TALIBUDEEN O.
Publication year - 1981
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1981.tb01691.x
Subject(s) - denitrification , nitrate , chemistry , zoology , effluent , steady state (chemistry) , environmental chemistry , biomass (ecology) , stoichiometry , nitrogen , agronomy , environmental engineering , environmental science , biology , organic chemistry
Summary In a very acid upland clay surface soil and with glucose added to give initial C/N weight ratios (added glucose‐C: NO 3 ‐N) in the soil of 0, 2 and 5, the rates of evolution of N 2 and N 2 O were maximum at C/N = 2 but were significantly less at 0 and 5. The total N 2 and N 2 O production was highest at C/N = 0, confirming that increasing amounts of glucose immobilised more nitrate into the biomass. As with added NO − 3 ‐N, the time lag, preceding a maximum ‘steady state’ rate of N 2 0 evolution, increased regularly with increasing glucose. Within this ‘steady state’ period, the gaseous CO 2 ‐C/(N 2 + N 2 O)‐N weight ratio in the effluent gas are between 1.0 and 1.3, which corresponds well with the stoichiometric ratios of 1.07 and 1.29 for the reduction of NO − 3 to N 2 O and N 2 respectively. Before and after this period, this gaseous C/N ratio was much higher. Denitrification was not observed in subsurface soil even after adding 100 mg kg −1 glucose‐C although it contained 4 times as much indigenous nitrate as the surface soil. Inoculating this soil with increasing amounts of the surface soil, up to 15 per cent by weight, induced substantial increases in the rates and amounts of denitrification. The effects of increasing the soil pH. of introducing increasing oxygen concentrations in the influent gas. and the fate of added NH + 4 ‐N, are briefly reported here. In these experiments. NO − 2 ‐N did not accumulate in the incubated soil nor was there any NH 3 in the effluent gas. Evolution of N 2 only occurred when N 2 O evolution was in its final stages.