Effects of Cultivation on Soils in Northern Great Plains Rangeland
- R. Aguilar ,
- E. F. Kelly and
- R. D. Heil
Paired rangeland and cultivated soils were characterized along toposequences formed in sandstone, siltstone, and shale parent materials in southwestern North Dakota to evaluate changes in organic constituents and total P resulting from 44 yr of cultivation. Cultivated and virgin grassland soils were compared on adjacent landscape segments in order to quantify losses or gains of organic C, N, P, and total P. Losses were generally greatest from the upper landscape segments where erosion resulted in significant reductions in solum thickness. Sediment accumulation through erosional processes and redistribution during tillage operations resulted in accretion on selected landscape segments along the cultivated fields. Soils derived from sandstone and siltstone appear to have lost larger proportions of organic C, N, and P through mineralization than the soils formed in shale. Mineralization losses of organic constituents were countered by accretion on depositional segments. Regression analyses indicated that losses of organic C, N, and P were more closely linked to erosion in the finer-textured soils formed in shale. Changes in total P were closely linked to redistribution and sorting of soil particles because the total quantity of P in soils is independent of mineralization transformation.
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