A method for the preparation of repacked soil cores with homogeneous aggregates for studying microbial nitrogen transformations under highly controlled physical conditions

The feasibility of studies on nitrate transformations during incubation in controlled conditions of air-filled porosity using a method of soil core preparation was investigated. Repacked cores were obtained by uniaxial confined compression in a cylindrical mould of a mass of calibrated and conveniently wet aggregates with a water content selected to saturate the textural porosity of the soil aggregates, imposing structural porosity and thereby producing controlled conditions of aeration. The principle and the description of the incubation method are explained and some denitrification and respiration data obtained with low and increasing O(2) partial pressures are presented. Reproducibility of the results was considered satisfactory and compared with published data; it was much better than the reproducibility of data obtained from the incubation of undisturbed soil samples and similar to those obtained with homogenized and unstructured samples. (C) Elsevier, Paris.