Characteristics of microbial biomass attributes in soil dry aggregates from lands of different uses in the semi-arid area

Soil aggregates are the basic units of soil structure and play an important role in soil quality and fertility. It is thus meaningful to investigate the natures and differences in biochemical properties of different soil aggregates. Moreover, it may be benefit to understand the essence of soil fertility and fundamental reason for the difference in fertility of different soils. In this study, 4 surface soils were sampled from woodland, none-irrigated cropland, irrigated cropland, and grassland in semi-arid region of Inner Mongolia. Six classes of soil aggregates with different diameters were collected with dry sieving method. The measured parameters included soil basic properties such as clay, organic matter, total nitrogen, K[sub 2]SO[sub 4] extracted carbon, and soil microbial biomass C (MBC), ATP, basal respiration and substrate-induced respiration. It is evident that the relationships among the soil microbial parameters does not change with soil aggregates though dramatically different in the absolute values.