Effects of Long-Term Located Fertilization on Humus Fractions in Black Soil

Humus plays an important role in soil fertilizer and it supports necessary nutrition that plants live on.The humus was divided into 6 fractions by Pallo method including FAf,HAs,HAp,FAs,FAp and HM(HAs and FAs are loosely united humus.HAp and FAp are steadily united humus.HM is tightly united humus.),and the effects of long-term located fertilization(ck,M2,M4,NPK,M2+NPK and M4+NPK) on humus fractions were studied in this paper.Results showed that the carbon content sequence of humus fractions was HApHAs FApFAfFAs.Long-term fertilization was beneficial to increasing the carbon content of SOC,FAf,loose humus,stable humus and tight humus,the ratio of Ⅰ/Ⅱ,and decreasing the ratio of Ⅰ/Ⅲ.High content organic fertilizer application combined with inorganic fertilizer was the best one compared with the effects of each fertilization treatment on different combined humus,but single inorganic fertilizer application was the worst.PQ and soil humification reaction increased after long-term single inorganic fertilizer application.