Abstract: In order to explore effects of land use on decomposition of soil organic carbon in the Loess Plateau, soil samples were collected from lands different in land use, woodlot, shrubland, natural grassland and farmland for analysis of soil organic carbon and its mineralization characteristics. Results show that no matter whether in soil organic carbon content, organic carbon density, mineralizable carbon content and organic carbon mineralization rate, natural grassland, shrubland and forestland are all higher than farmland; while in soil organic carbon mineralization rate and soil respiration rate, farmland and arbor-shrub land are higher than natural grassland and shrubland. During the 1575 h of soil incubation, soil mineralization, regardless of land use,can be divided into four phases: 0.5─5 h (first phase), 5─111 h (second phase), 111─399 h (third phase), 399─1 575 (fourth phase). The first 399 h is the main period when minerlizable carbon is emitted; during the first 111 h, soil mineralization carbon emission rate peaks and drops the fastest too; as a whole, cumulative soil mineralizable carbon emission increased and cumulative emissions rate gradually decreased with the incubation going on. Soil organic carbon mineralization rate is closely related to the content of total organic carbon, and soil respiration is not so related to the content of total organic carbon or total mineralized carbon.

Key words: tablel of the Loess Plateau, land use types, organic carbon, soil respiration, soil mineralizable carbon