Document: JAY-3-63-2

What makes the desert bloom? The contribution of dust and crusts to soil fertility on the Colorado Plateau.

BELNAP, J.* ¹, R.L.REYNOLDS ², M.REHEIS ² and S.L.PHILLIPS ¹

USGS-BRD, Moab, UT 84532 ¹
USGS, Denver, CO ²

Abstract:
Eolian dust (windblown silt and clay) and biological soil crusts are both important to ecosystem functioning of arid lands. Dust furnishes essential nutrients, influences hydrology, contributes to soil formation, and renders surfaces vulnerable to erosion. Biological soil crusts contribute directly to soil fertility by fixing carbon and nitrogen, and indirectly by trapping newly-deposited dust and stabilizing already-present soil. Results from crust-stabilized, unconsolidated sandy sediments on prominent rock exposures and grasslands show dust inputs have significantly increased all bioessential nutrients in soils of South East Utah, including P, K, Mg, Na, and Ca. As plants can be P and K-limited in these soils, dust may be essential for plant growth. Petrographic and magnetic analyses reveal that a large component dust particles have been derived from igneous rock areas. This result and the particle-size data indicate long-range (10s to 100s KM transport), perhaps as distant as the Mojave desert. Dust in the biological soil crusts, when compared to underlying sediment, show higher magnetite, Zr, and Zr/Ti, suggesting that dust sources have changed over the past few decades. It is suggested that recent human disturbance in areas surrounding the Colorado Plateau may be responsible for this change in dust source.

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This abstract is being presented at: 2:00 PM in session:
Oral Session #13: N Fixation and Biochemical Patterns.