| Soil humus is a special high molecule compound in soil. It has important function in soil fertility, structure and character. So, it is important to the study of humus in agriculture produce and environmental protection. Previously, we mainly studied solvable humus fraction(humic acid,fulvic acid), however, the study of unsolvable humus faction(humin) was litter.This paper makes the method of Pallo simply, and humin was divided into three fractions. The paper studied the fractional composition of organic matter by the method, mainly the mounts and some chemical characteristic of humin fraction from three different soil types, namely black soil, meadow soil and wind-blown soil in the northeast of china, and the dynamic changes of humin fraction during incubation experiments. The objects are to provide scientific basis for clarifying the formation and transformation mechanism of humin , and give new data for fertility of soil and organic chemistry and humic substances chemistry .The major results are as follows:In the fraction of organic matter from three different soils , the amounts of extractable humus was higher, accounting for 30%~50% of total carbon. The result of humin fraction indicated that the amount of isolatable humin (HMr) was the highest , accounting for 30%~60% of total carbon .The amount of humin linked to iron (HMi) was more than the humin linked to clay (HMc) .The amount of HMi accounted for 3%~6% of total carbon. The amount of HMc accounted for 1%~5% of total carbon.The study of HMi and HMc's E4/E6 and ALogK indicated that the molecular structure of HMi was simpler, but the molecular structure of HMc was more complex .The molecular structure of the new formed HMi and HMc were the simplest. The study of IR showed :The aliphatic of HMi and HMc was stronger than humic acids extracted with pyrophosphate of sodium, humic acids extracted with soda and fulvic acids extracted with pyrophosphate of sodium. In different type soils , The aliphatic of new formed organic matter compose is the strongest among these soil. The aliphatic of HMi and HMc in Wind-blown soil was stronger than in black soil. Meadow soil was weak.During corn stalk decomposition , the amounts of organic matter carbon and the relative amounts of free fulvic acid(FFA) gradually decreased with prolonged incubation time ; Therelative amounts of extractable humus (HE)increased before 90 day and then decreased .The relative amounts of HMi and HMc increased gradually , the amounts of HMr first increased , then decreased.At early stage of incubation, PQ gradually decreased, then increased in the treatment of soil/corn stalk 1:1 and soil/corn stalk 2:1, it indicated that the formed velocity of FA was more faster than HA in initial stage, then the formed velocity of HA gradually increased .While in the treatment of soil/corn stalk(sterilization) 2:1, the formed velocity of HA was faster than FA at initial stage .During corn stalk decomposition, the formed velocity of HA and FA were more faster than HMi and HMc , while with prolonged incubation time , each treatment was benefit to formation and accumulation of HMi and HMc . Compared with HA, it was benefit to the accumulation of HMi and HMc in soil/corn stalk 1:1 's treatment. Compared with FA, it was not benefit to the accumulation of HMi and HMc in soil/corn stalk 3:l's treatment.In early stage(0~30d) of corn stalk decomposition , the amount of HMi accumulation was higher than in the soil/corn stalk 1:1 's treatment. After 30d, the accumulation of HMc increased. At the end of incubation, the value of HMi/HMc in the soil/corn stalk 3:l's treatment was higher, then is the soil/corn stalk 2:1 's treatment , the value of HMi/HMc in the soil/corn stalk 1:1 's treatment was lower. So we speculated that HMi/HMc and soil/corn stalk is positive after a long time cultivation, the value of soil/corn stalk was higher , more benefit to formation of huniin fraction, the formation velocity of HMi and HMc was faster than HMr. So during corn stalk decomposition , it was benefit to the transformation...
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