THE COMPOSITION CHARACTERISTICS OF LOW-MOLECULAR-WEIGHT ORGANIC ACIDS IN SOIL AND THEIR ROLES ON SOIL MATERIAL CYCLING

The recent three decades' developments in the research of low-molecular-weight organic acids (LMWOAs) in soil were generally reviewed. Firstly, the composition characteristics and sources of LMWOAs in soil and their influenc factors were summerized. Secondly, the roles of LMWOAs on soil material cycling, expecially on the weathering and formatiori of minerals, transformation of nutrierits (Fe, P, S), soil alumirium toxicity, interactions with heavy metal in soil and themseleves toxicity to plant growth, were discussed. Finally, some concerning research issues that they should be paid more attention in the future were posed.