Central Nevada riparian areas: Physical and chemical properties of meadow soils

Abstract

Despite the importance of soil characteristics for classifying riparian ecosystem types and evaluating ecosystem or range condition, little information exists on western riparian area soils or the factors that influence them. We examined the effects of drainage basin geology and water table depth on soil morphology and soil physical and chemical properties of meadow sites in central Nevada. We described and analyzed the soils of meadows that occurred in 4 drainages with different geology and that exhibited high water tables (0 to -20 cm from the surface), intermediate water tables (-30 to -50 cm), and low water tables (-60 to -80 cm). Pedons of high water tables sites had thick Oe horizons, dark, fine-textured A horizons, no B horizons, and lower C horizons high in coarse fragments. In contrast, pedons of low water tables sites were characterized by deep, dark and organic-rich A horizons, cambic B horizons, and deep rooting profiles. High water tables sites had higher organic matter, total nitrogen, cation exchange capacity, and extractable potassium, but lower pH than low water table sites. Also, high water table sites had lower percentage sand, lower bulk densities, and higher soil moisture retention. The importance of organic matter was evidenced by strong positive product moment correlations for organic matter and total nitrogen, cation exchange capacity, and extractable potassium. Significant differences in pH, extractable potassium and extractable phosphorus existed among drainages that were explainable largely from the parent materials. Drainages with chert, quartzite, and limestone had higher silt and clay, neutral pH, and high levels of extractable phosphorus. Drainages formed in acidic volcanic tuffs, rhyolites and breccia were characterized by coarser textured soils and low pH and extractable phosphorus. In riparian areas, soil water table depth interacts with soil parent material to significantly affect soil morphology and soil physical and chemical properties. Because these factors vary over both large and small spatial scales, differences among sites must be carefully interpreted when classifying ecosystems or evaluating ecosystem condition.