Carbon dioxide produced in each vessel reacted with the KOH in
the cup to form potassium bicarbonate. The amount of CO2 produced
was determined by titrating the KOH solution with 0.25 N
hydrochloric acid (Fisher Scientific, PA, U.S.) to a phenolphthalein
end-point. The experiment was designed so that the headspace
volume was sufficient to prevent the oxygen concentration in the
vessel from falling below 18%. The KOH traps were removed and
titrated at time intervals that assured that their absorption capacity
was not exceeded. The KOH traps were refilled at a rate dependent
on the rate of CO2 generation in each flask. At the time of removal of
the traps, the vessel was flushed and allowed to sit open to allow
fresh air to fill the headspace. In addition, distilled water was added
to the soil to the original weight to maintain adequate moisture.
sealed and incubated at room temperature (20 2 C).
specimen.
in triplicate for a period of 660 days.