Submitted to: Resource Conservation Act Appraisal
Publication Type: Government Publication
Publication Acceptance Date: June 1, 2011
Publication Date: July 1, 2011
Citation: Weltz, M.A., Jolley, L., Herrick, J.E. 2011. Chapter 3 The state of the land. Resource Conservation Act Appraisal. p. 25-48. Technical Abstract: The USDA-Natural Resources Conservation Service (NRCS) has used resource inventories for over 65 years to assess the Nation’s natural resources on non-Federal lands. Since 1995, an interagency group composed of the NRCS, Agricultural Research Service (ARS), and Geological Survey (USGS) have worked together to develop a robust field approach for National Resource Inventory (NRI) on rangeland. The new NRI protocols are designed to detect long-term changes in the condition on rangeland ecosystems, and monitor short-term impacts. A new process based model was developed by ARS for assessing soil erosion rates on rangelands in support of the Conservation Effects Assessment Project (CEAP). The Rangeland Hydrology and Erosion Model (RHEM) were developed on data collected exclusively from rangeland erosion experiments. The model was designed to be used by NRCS Range Conservationists when sampling for the NRI. The RHEM tool was used to calculate runoff and erosion at 10,000 NRI sample points in the 17 western states on non-Federal rangelands. National average annual erosion rate on non-Federal rangeland is estimated to be 0.63 ton ac-1 year-1. Nationally 20% of non-Federal rangelands generate over 65% of the average annual soil loss. Over 72 million ac or 18% of the non-Federal rangelands might benefit from treatment to reduce soil loss to below 1 ton ac-1 year-1. However, national average annual erosion rates combine areas with low and accelerated soil erosion and can misrepresents the magnitude of the soil erosion problem. Between 23 and 29% (92 to 106 million ac) of the Nation’s rangelands are vulnerable to accelerated soil loss (soil erosion > 1 ton ac-1 year -1) if assessed as a function of vulnerability by using the risk of a runoff event of a given magnitude (25 or 50 year return storm event). NRCS has not evaluated potential erosion risk in National reports in the past and adaptation of this technique will allow USDA and its partners to be proactive in preventing accelerated soil loss.