Effect of Temperature on Organic Carbon-texture Relationships in Mollisols and Aridisols
1985
McDaniel, P. A. | Munn, L. C.
Data from 143 grassland soils of Montana and Wyoming classified as Mollisols or Aridisols were analyzed to determine the effect of soil temperature regime on the relationship between organic carbon (C) and texture. Using existing data, average weighted organic C content to a 40-cm depth was calculated for each soil and correlated with several variables, including elevation, weighted clay and sand contents to a 40-cm depth, and sand/clay ratio. For all soils, organic C was significantly correlated with sand (r = − 0.27) but not with clay (r = 0.01). When soils were grouped by combinations of temperature regime and classification at the order level, organic C levels were highest in cryic soils (Cryoborolls) and lowest in mesic Aridisols. Correlations of organic C with sand and clay contents were highest for mesic Mollisols and mesic Aridisols and decreased as temperature regimes became colder. Sand/clay ratio was significantly correlated with organic C in mesic soils only, and therefore may not be useful in distinguishing between Typic and Borollic subgroups of frigid Aridisols in Soil Taxonomy. Results suggest that sand and clay contents have limited value in predicting organic matter levels in cold arid and semiarid grassland soils.
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