Relationship between mineral N content and N mineralization rate in disturbed and undisturbed soil samples incubated under field and laboratory conditions
1992
Sierra, J. (Univ. of Buenos Aires (Argentina). Departamento de Suelos)
An investigation of in situ N mineralization, using undisturbed soil samples, indicated a negative relationship between the mineral N content at the beginning of the experiment and the mineral N produced during it. This suggests that a maximum value of mineral N accumulation in intact soil cores could be calculated from the relationship between mineral N content and N mineralization rate. The aim was to verify this hypothesis. The relationship between the mineral N content and the N mineralization rate was analysed for in situ and laboratory incubations of disturbed and undisturbed soil samples. A negative relationship between the 2 variables was only obtained for the experiments carried out with undisturbed samples when the soil moisture content was not limiting for N mineralization. Furthermore, in undisturbed samples, a negative relationship between mineralization rates of consecutive incubation periods was observed. This relationship suggests a feedback mechanism operating in N mineralization which would be related to a mineralization-immobilization process in soil microsites. Thus, the N mineralization pattern was more complex than that described by the initial hypothesis. The possible consequence of this feedback mechanism on in situ N dynamics is discussed.
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