Effect of Water-table Level on Nitrogen Mineralization in Peat

The effect of drainage on the mineralization of nitrogen inpeat has been investigated using samples from a field experimentin which the water table has been artificially maintained atdifferent levels in five plots for a period of 7 years. Samplescut from the o–10 cm horizon were incubated in the laboratoryat 30 °C for 120 days in a moist condition (aerobic) andalso in a completely waterlogged state (anaerobic). The resultsof anaerobic incubation indicate that lowering the water-tablelevel to 18 cm significantly decreases the amount of nitrogenmineralized but that further lowering of the water level reversesthe position, mineral nitrogen increasing significantly at leastto a water-table depth of 34 cm; the position regarding samplesincubated under aerobic conditions is more complex but can beexplained on the basis of samples containing a mixture of aeratedand non-aerated material.