Crop-specific differences in the concentrations of lipids in leachates from the root zone

Although lipids are involved in diverse soil processes and affect various soil properties, the contribution of rhizodeposits and the root zone to lipid concentrations and distributions in soils is unknown. For the first time, we determined the concentrations of alkanoic acids, n-alkanes and n-alkenes in root zone leachates and roots of maize and potato using gas chromatography/mass spectrometry (GC/MS). In total, the lipid concentrations of leachates were 100 μg g^?1 (maize) and 17 μg g^?1 (potato). The saturated n-alkanoic acids, ranging from n-C₁₄ to n-C₂₈ and having the maximum at n-C₂₂ (maize) and at n-C₁₆ (potato), were more abundant than the other compounds. Maize leachates had more alkanes (20 μg g^?1) than potato leachates (3.1 μg g^?1), but the members of the homologues were nearly the same. Comparison of these distributions with data for roots, microorganisms and soil indicated that the lipids in the leachates from the root zone mainly originated from abrasion of fine roots, rhizodeposits and rhizosphere microorganisms.