Effect of corn straw on the fraction variation and properties of humic acid in lousoil during different decaying periods
不同腐解期玉米秸秆对塿土胡敏酸基本性质及级分变异的影响

On the basis of studying the properties of humic acid in the soil with application of corn straw in different decaying time, the alcohol precipitation technique was used for classifying soil humic acid into 7 fractions and the fraction composition of humic acids and their properties were researched. The results showed that the type of humic acid changed from type A to B and then to A during the whole decaying periods of corn straw. Humic acid changed from complex to simple and then to complex again. The fractional composition of humic acid differed as the decaying time going on. The process of renewal of humic acid by corn straw has two direction , One was that it made the complex fractions become simple ,and the other was that some small molecular humic acid condensed from type R p to P then to A as the time going on.