Wednesday, 9 November 2005
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Soil Amendments to Enhance Biological Crust Establishment in a Sandy Desert Soil.

Inmaculada Lebron1, Jayne Belnap2, and David Chandler1. (1) Utah State University, 4820 Old Main, Logan, CA 84322-4820, (2) USGS, 2290S West Resource Blv., Moab, UT 84532

Biological soil crusts, also ‘cryptogamic', are a composite of multiple organisms that protect the soil in arid environments from water and wind erosion. They also play an important role in holding and distributing water and nutrients to the vascular plants. Biological crusts are very fragile when dry and easily disturbed by foot, cattle and vehicular traffic, thus exposing the soil to erosion processes. Whereas disturbance is a fast process, regrowth is extremely slow, and can take decades or even hundreds of years. One limitation for establishment of biological soil crusts is that unstable soils do not present an ideal environment for cyanobacterial colonization. In this work we tested the effect of several amendments on soil physical properties, with the intent of improving conditions for establishment of cyanobacteria, and hence biological crusts, in a disturbed area near Moab, UT. Each 1x1m plot was seeded with cyanobacteria, and added nutrients. Gypsum, polyacrylamide, and sodium chloride were applied to individual plots to test for both positive and negative impacts of proposed rehabilitation strategies on soil physical properties and biological activity, relative to the blank treatment (cyanobacteria and nutrients only) and a control (water only). In total we had four replicates for each treatment. After four months marked differences among the treated plots were observed: Treatment with sodium chloride plots resulted in a very flat soil surface with a strong physical-chemical crust. Gypsum and polyacrylamide treatment resulted in noticeably greater surface roughness and cracking, presumably due to a combination of freezing and thawing processes. Control and blank plots also presented cracking and roughness but to less extent than the gypsum and polyacrylamide plots.

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