Experimental leaching of podzol soil lipids. Nature and biological origin of water soluble components
Résumé
In order to determine the ability of soil lipids to migrate through natural leaching by rain water, litter and soil A1 horizon of a podzol soil were sampled. Samples were placed in glass columns and experimentally leached with distilled water slowly delivered by a peristaltic pump. Soluble lipids were extracted from leachate with chloroform. Hydrocarbon, fatty alcohol and fatty acid fractions were isolated from soluble lipids by column chromatography after saponification and methylation. The soluble components of each family were determined by GC and GC-MS then compared to soil lipids previously analysed. The results showed that the water soluble fraction of lipids was very low and mainly released by the litter sample. A decoupling of hydrocarbons, fatty alcohols and fatty acids was observed in the dissolved and in the total lipid phases, the components of the soluble phase being chiefly of microbial origin and those of the total phase essentially of plant origin.