Effect of long-term fertilization on the organo-mineral complexation and the combined forms of humus of black soil

Effect on long-term different fertilization on the combined forms of humus and the organo-mineral complexation of black soil were studied on the basis of long-term located experiment.The results showed that the contents of organic carbon in soil and heavy fraction and the quantity of organo- mineral complexation were increase with varying degrees under different treatments of longterm fertilization, the degree of organo-mineral complex was decrease in the same way. The contents of the loosely combined humus was richest, the contents of the stsbly combined humus was moderate, the contents of the tightly combined humus was the smallest in all fertilizer treatments. The content of theloosely combined humus, the stsbly combined humus and the ratio of loosely to tightly combined humus tended to increase and the content of loosely combined humus and ratio of loosely to stably combined humus tended to decrease under the fertilizer treatments. The fertility of soil under the chemical fertilizer treatment tended to increase in 0-20 cm layer and tended to decrease in 20-40 cm layer. The organic manure and chemical fertilizers treament improved of soil in the greatest extent, made the humus most active, the influence is stability in the two layers. The effects of the organo-mineral complexation under fertilization in 0- 20 cm layer was greater than 20- 40 cm layer and the effects of combined forms of humus under fertilization in 20-40 cm layer was greater than 0-20 cm layer.