The effect of soil temperature on denitrification and ammonification [electronic resource].

Includes references.

A laboratry study was conducted to determine the effects of temperatures from h-I-to 30"C on denitrification and ammonificanon in anaerobic soil treated with guar or glucose. Organic C substrate as guar or glucose increased denitrification rates at all temperatures within this range and lowered the threshold temperature at which denitrification occurred. The threshold temperature for denitrification was as low as -1c in unfrozen (supercooled) soil in contrast to most other studies where the threshold temperature was reported to be at or above 0 C. When soil was frozen at -I"e. the denitrification rate was much lower than in unfrozen soil at the same temperature. A square root model was employed which showed that the square root of the denitrification rate was linearly related to temperature from -I to 30"e. The maximum amount of NO:; produced during the incubation periods generally decreased from -I to -,WC and was greatest when glucose and especially guar were added. The rate of ammonification increased with addition of guar but the quantities of NH; produced generally decreased from 30"C to -l"e.

Summary in Arabic.

1