Figure 1.
Nitrification kinetics in soil microcosms incubated for 28 days at 30 °C with regular additions of ammonium to maintain target concentrations of 0, 20 and 200 μg NH4+-N per gram of soil. (a) Ammonium concentration in soil microcosms that were either destructively sampled or amended with water or ammonium sulfate solution at intervals of 3.5 days. Arrows indicate the times at which ammonium was added to soil microcosms and associated numbers describe the increase in ammonium concentration (μg N per gram of soil). (b) Nitrite+nitrate concentration in soil microcosms produced from oxidised ammonia. Each point and error bar represents the mean and standard error of triplicate microcosms, with some error bars smaller than the symbol size.