Climatic and Topographic Relations of Three Great Plains Soils: II. Carbon, Nitrogen, and Phosphorus
1990
Honeycutt, C. W. | Heil, R. D. | Cole, C. V.
Mechanisms controlling the mineralization and stabilization of organic C and N in soils have been proposed to differ from those for organic P. This study was designed to analyze the climatic and topographic controls on steady-state levels of soil C, N, and P under relatively undisturbed management. Soil catenas were examined in three climatic zones characterized by mean annual precipitation (MAP) of 395, 444, and 514 mm and mean annual temperature (MAT) of 10.8, 10.7, and 11.5 °C, respectively. Soils of the Argid and Ustoll suborders were studied. Increase in MAP from 395 to 444 mm was associated with increases in organic C and total N of 46 and 24%, respectively. Increasing MAP from 444 to 514 mm with a 0.8 °C increase in MAT did not change organic C and total N; however, levels of organic P increased from 0.144 to 0.167 kg m⁻³. Organic-C concentrations were highest in the surface horizons and declined with depth, but relatively high concentrations of organic P were found in the subsoils studied. The depth of this organic-P-accumulation zone varied in patterns indicative of climatic and topographic controls on the leaching process. Both the total contents and vertical distributions of organic C and P, therefore, suggest that stoichiometic relationships between C and P should not be assumed, as both climate and topography may influence soil C and P levels to different extents and through different processes.
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