INCORPORATION OF NATURAL HYDROCARBONS FROM PLANT RESIDUES INTO AN HYDROMORPHIC HUMIC PODZOL FOLLOWING AFFORESTATION AND FERTILIZATION

The content and composition of natural hydrocarbons from plant residues (Pinus maritima sp.) of a hydromorphic humic podzol were investigated following the addition of NPK and P fertilizers. L and F layers and the A1 horizon from non-fertilized and fertilized soil were analysed for total lipids and hydrocarbons, and non-linear and linear hydrocarbons. The decrease in non-linear hydrocarbons extracted following the addition of fertilizers was attributed to the incorporation of non-linear hydrocarbons into humus, rather than to their biodegradation by soil micro-organisms. Short- and medium-chain linear hydrocarbons from plant residues or of microbial origin were rapidly biodegraded or fixed by soil micro-organisms, resulting in a very low concentration in the A1 horizon. In contrast, long-chain linear hydrocarbons of plant origin accumulated in the non-fertilized soil, while the addition of P fertilizer slightly stimulated their biodegradation.