Effect of land use type on profile distribution of glomalin

Despite evident importance of glomalin in maintaining soil organic carbon balance and soil aggregate stability, little remains known about soil profile distribution patterns and influencing factors of glomalin under different land use types. In this study, we selected four land use types (farmland, artificial grassland, orchard and abandoned land) to examine soil profile distribution patterns and influencing factors of glomalin. Soil samples were collected from depths of 0~10 cm, 10~20 cm, 20~30 cm and 30~40 cm respectively. Soil glomalin, pH, available phosphorus, organic carbon and protease activity were determined for the collected soil samples. The results show that average soil glomalin content ranges from 1.41~3.18 mg·g^-1, accounting for 6.98%~31.34% of soil organic carbon. Glomalin is therefore regarded as a major carbon pool in soil. Significant differences in soil glomalin are observed among the land use types and soil layers (P< 0.01). Soil glomalin exhibits obvious vertical distribution pattern, which decreases with increasing soil depth (except for abandoned lands). Soil glomalin is significantly directly related with soil available phosphorus and protease (P< 0.01). Soil available phosphorus, to a large degree, determines the content and distribution of soil glomalin. A simple and indirect correlation is observed between soil glomalin and protease. However, more research is recommended to further clarify the relationship. Based on the study, we conclude that glomalin is an important indicator for arbuscular mycorrhizal hyphal growth and variations in soil ecosystem.