title: The density of Azotobacter in root-free soils and in the rhizosphere of several plants in arid and semi-arid Libyan regions.
mesh_terms: D001395:Azotobacter / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D002452:Cell Count; D003720:Densitometry; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D008002:Libya; D010944:Plants; D012987:Soil; D012988:Soil Microbiology; D013045:Species Specificity; D014329:Tropical Climate
chemical_list: D006812:Humic Substances; D012987:Soil