Organic matter in bare soils of the mediterranean region with a semiarid climate

Bare soils, with different textures, from different areas of the Spanish Mediterranean area with a semiarid climate were studied. Because of the important role that the organic matter plays in these soils, the different C fractions were determined and the dynamics of mineralization of the organic matter was followed by means of soil respiration experiments. Total organic C (TOC) content of these soils was low, as was the extractable C × 100/TOC ratio. Very high overall mineralization rates were observed in those soils of a loam or sandy loam texture. Bare soils having silty‐clayey loam or clayey loam texture had the lowest rate of extractable C mineralization. The lowest values for basal respiration and k × m (microbiological activity) corresponded to soils with high electrical conductivity or low TOC content. The process of C mineralization in these soils occurred in two stages of differing first‐order kinetics, the sandy loam soils showing the highest values. Values for electrical conductivity in the so...

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