Soil Organic Carbon, Nitrogen, and Phosphorus Quantities in Northern Great Plains Rangeland

Soils were characterized in North Dakota rangeland along toposequences formed in sandstone, siltstone, and shale parent materials to evaluate quantities of organic C, N, P, and total P. Distribution of these soil constituents varied systematically with parent material and landscape position along the three toposequences, and generally increased upon moving downslope. The fine‐textured soils formed in shale had greater quantities of organic C, N, and total P than the coarser‐textured soils derived from sandstone and siltstone parent materials. Soils formed in sandstone had greater quantities of organic P on all landscape segments. Greater quantities of organic constituents on lower landscape segments were attributed to both greater vegetative productivity and accretion of soil organic matter through sediment deposition. Variable total‐P contents along the toposequences reflected changes in parent material and redistribution of sediments by erosion.