Influence of 15NH4+ -application on gross N turnover rates in soil
2003
Luxhoi, J. | Nielsen, N.E. | Jensen, L.S.
Determination of gross N mineralization rate in soil, by use of the isotopic pool dilution approach implies that 15NH4(+) is applied homogeneously to soil. Since the labeling is applied to the product of the mineralization, the application of 15NH4(+) should in theory not alter the mineralization rate. However, recent studies have indicated inverse relation between the amounts of 15NH4(+) applied and the determined gross N mineralization rates, due to overestimated rates when 'low' amounts of 15NH4(+) were added, as a result of preferential 15NH4(+) consumption. We present here results from a similar study. We observed no effect from the amount of applied NH4(+) on the measured gross N mineralization rates. Our results indicate, that the inverse relation as described earlier, probably was due to underestimated rates when 'high' amounts of 15NH4(+) were added, as a result of preferential 14NH4(+) consumption, when the applied 15NH4(+) was incomplete distribution in the soil.
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