Hot-water-soluble Carbon and Surface Properties of Water Repellent Soils

摘要

Hot-water-extraction of water repellent soils from Australia, Portugal and UK eliminated soil water repellency (SWR) in the soils studied. Gas chromatography/mass spectrometry (GC/MS) analysis showed that the dominant compounds were aromatic acids, short chain dicarboxylic acids (C_(4)-C_(9)), sugars and esters of stearic and palmitic acids. Aromatics and dicarboxylic acid contents increased upon saponification due to cleavage of ester bonds of high molecular weight and polar compounds. Specific surface area and pore distribution showed that the sandy loam and loamy sand soils from Australia had micropores and adsorbed water more efficiently than the sands, while the sandy loam soil from Portugal having a higher content of aromatics in the hot-water-soluble extracts, was strongly water repellent. SWR may intensify upon drought. It has an effect upon soil organic matter (SOM) decomposition and plant productivity, as well as the microbial community structure and the overall carbon balance.