Development of immobilized cyanobacterial amendments for reclamation of microbiotic soil crusts

Abstract

Cyanobacteria were immobilized on hemp cloth, which was subsequently cut into fine pieces for use as a soil amendment. The amendment is intended for speeding recovery of microbiotic soil crusts in semi-arid and arid lands where such crusts have been destroyed by anthropogenic activities. Microcoleus vaginatus, Schizothrix calcicola, and Nostoc were used to create amendments, but most of the experiments in this study utilized the Microcoleus amendment, as it is the most cosmopolitan and ecologically important cyanobacterial taxon in desert soil crusts. The amendment was found to retain its viability in storage for at least 18 months. M. vaginatus grew best in CT and Z8+ (plus vitamins) media with aeration and addition of KHCO 3 . A field test of Fort Irwin National Training Center, Mojave Desert, California, showed significant increases in phototrophic biomass 6 and 12 months after inoculation, but the stimulans was not evident at 18 months. Four other field tests did not show significant gains. We suspect the failure of the field tests is due to a loss of cyanobacterial viability after inoculation but before favorable growth conditions. Cyanobacteria were possibly killed by UV irradiation or photo-oxidation in the hot desert environment M. vaginatus is known to live below the surface in desert soils, and so likely is sensitive to full sunlight. Laboratory experiments in full sunlight verified this hypothesis.