Soil hydrophobicity in Andisol under soil surface burning
2009
Obuchi, A., Tokyo Univ. (Japan) | Mizoguchi, M. | Nishimura, T. | Imoto, H. | Miyazaki, T.
Soil is known to exhibit hydrophobic properties after a forest fire. Experiments conducted by DeBano et al., (1976) showed that the organic compounds in the soil become volatized under high-temperatures, move downward along the soil temperature gradient, and form a hydrophobic layer deep within the soil profile. However, less is known about effects of oxygen atmosphere on morphological changes of organic matter in soil. In this study, we sought to clarify the increase in soil hydrophobicity as well as the changes in carbon and nitrogen content in response to heating of the ground surface in the field and both column and muffle furnace heating in the laboratory. In the muffle furnace burning, soil samples heated under oxygen-deprived conditions exhibited similar carbon and nitrogen dynamics and increased hydrophobicity with temperatures those observed in the field and column experiments. Soil samples under oxygen-deprived condition showed hydrophobicity and some carbon content by heating with 300degC and higher, while almost no carbon remained after heating with 400degC under oxygen available condition. Soil C/N ratio increased by heating with higher temperature under oxygen-deprived condition. Results suggested limited supply of oxygen might have an effect to produce soil hydrophobicity under soil surface burning.
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