Abstract: The use of artificial cyanobacteria crusts is one of the effective methods to prevention and control of desertification. Soil fine substance is one of the important factors limiting the colonization and growth of artificial cyanobacteria crusts. We compared the growth of artificial cyanobacterial crusts with different fine substance contents by setting the volume ratios of fine substance to quicksand as 0:1, 1:1, 2:1, 4:1 and 1:0. The results showed that the cover of artificial cyanobacteria crusts increased gradually with the increases of fine substance contents, while the contents of chlorophyll a and extracellular polysaccharide firstly increased and then decreased slightly. The optimum growth of artificial cyanobacterial crusts was achieved under the treatment of 4:1 ratio. Under such treatment after 60 days of incubation, artificial cyanobacteria crusts cover was 70%, and the contents of chlorophyll a, loosely bound exopolysaccharide (LB-EPS), tightly bound exopolysaccharide (TB-EPS), and glycocalyx exopolysaccharide (G-EPS) were 17.5, 70.0, 175.0, and 200.0 μg·cm^-2, respectively. Increasing the amount of cyanobacteria under the condition of low fine substance content could promote the formation and growth of artificial cyanobacterial crusts (0.5 g of cyanobacteria per petri dish was the optimal). It could provide a new idea for the large-scale culture of artificial cyanobacterial crusts inoculum.

Key words: soil fine substance, artificial cyanobacteria crusts, desertification, particle size