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Soluble Element Distributions in a Mojave Desert Soil
Author(s) -
Marion G. M.,
Verburg P. S. J.,
Stevenson B.,
Ar J. A.
Publication year - 2008
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2007.0240
Subject(s) - soil water , weathering , environmental chemistry , calcite , chemistry , leaching (pedology) , gypsum , saturation (graph theory) , supersaturation , lessivage , cation exchange capacity , geology , soil science , mineralogy , geochemistry , paleontology , mathematics , organic chemistry , combinatorics
The distribution of chemical species in desert soils is a complex function of atmospheric inputs, rock weathering, chemical equilibria, soil leaching, and plant cycling. In this study of the surface 1 m of desert soils at the Nevada Test Site, we examined the distribution of soluble soil elements beneath plant canopies and in intershrub zones. We extracted water‐soluble chemical species using saturation extracts that were equilibrated overnight and more dilute extracts that were incubated for 1 mo. All soil horizons were supersaturated with calcite and undersaturated with gypsum. Calcite supersaturation was a function of soil organic C (inhibitor) and water content (inhibitor diluent). It is critical that the latter two properties be explicitly recognized in modeling CaCO 3 mobility through soils. Plant‐essential cations (K, Ca, and Mg) were highest in concentration in surface soils beneath plant canopies. Sodium, Cl, NO 3 , and SO 4 were generally highest in concentration around 1‐m depth. The dissimilar patterns of essential nutrient accumulations between the cations (Ca, K, and Mg) and the anions (NO 3 and SO 4 ) were probably due to the greater mobility of anions than cations. Also, these surface soils were “N saturated” due to their low N retention capacity, which accounts, at least in part, for the anomalous NO 3 accumulations at depths >1 m in Mojave Desert soils. Furthermore, once NO 3 or SO 4 have leached to deeper soil depths, they may be relatively unavailable for plant uptake. The soil elemental patterns are consistent with elemental plant requirements and elemental mobility.