Soil samples were collected in 4 replicates and divided a depth of 50 cm into 5 sections,i. e. 0-10,10-20,20-30,30-40 and 40-50 cm in the rhizosphere of each plant in two representative sites from north to south in Mu Us sandland.
An antibiotic producing strain Streptomyces violaceusniger was isolated from soil sample, characterized and studied for antibacterial and antifungal activity profile.
These points can be estimated by introducing the soil factor (Ks) and tree species factor (Kt) to potential evapotranspiration with the Penman formula.
Root biomass, length, and the number of roots in every diameter class, for each soil layer and for each plant species, are regarded as observation variables.
The results show that most of the vertical distributions of plant roots belong to the type wherein the roots are concentrated in the topsoil layer (0-20 cm), far more than those in the lower soil layers.
Ecological Benefit of Reforestation in a Severely Degraded Red Soil Region