Microbiological and micromorphological characteristics of extremely arid desert soils in the Ili Depression (Kazakhstan)

The high biological diversity and the high activity of microorganisms were determined in the extremely arid desert soils developing under very sparse vegetation during the period of rare rains. Green and diatomaceous algae, dinoflagellates, cyanobacteria, and iron bacteria were diagnosed in the edaphon. These microorganisms affect the geochemical processes in the soils, including the biogenic transformation of rock minerals. Amorphous compounds of Fe 3+ and Mn 3+ are concentrated around the cells of iron bacteria and produce specific iron and iron-manganic pedofeatures. The specific humus-accumulative process is also developed owing to the mineralization of the microbial biomass with the formation of organomineral coagulates in the zones of contact of the intraped mass with rock debris covered by iron films and in the biogenic films on the walls of vesicular pores.