Submitted to: Columbia Basin Agricultural Research Annual Report
Publication Type: Experiment Station
Publication Acceptance Date: 2/1/2001
Publication Date: N/A
Interpretive Summary: This manuscript explores the geological, biological, and climatological conditions under which the small fourth and fifth order watersheds have developed on the Columbia Plateau and Palouse regions of the interior Columbia River watershed. Following settlement by Europeans, conditions in these watersheds have changed considerably and resulted in changes to the way water is released following individual storm events and seasonal cycles. These changes and future changes are explored in the context of a possible increase in conservation tillage systems, particularly the use of no-till farming practices. A preliminary analysis of the effect that no-till farming might have on small watershed hydrology suggests that increased no-till farming practices alone will not result changes to the current rapid loss of water.
Technical Abstract: Dryland farming practices are changing from intensive (conventional) cultivation toward no-till systems. These changes are occurring largely as a result of increased fuel and labor costs, and increasingly as one solution for controlling soil erosion to improve soil and water quality. In the U.S., the only practice that has equal potential to decrease soil erosion and runoff is the conservation reserve program (CRP). Although much highly erodible land has been entered into CRP, CRP was never intended to include more than a small percentage of land currently being cropped. No-till systems have the potential for becoming a major, if not primary, farming practice throughout the U.S. The difference between no- till and conventional cultivation is stark; conventional systems require from two to six passes through the soil with tillage implements that severely disturb the soil, whereas a no-till system can require one pass with minimal soil disturbance. In the dryland croplands of the interior Pacific Northwest, this change will result in diminished soil losses, and potentially influence storm and annual hydrographs of many of the smaller tributaries of the Columbia River. The decreased soil loss will have positive impacts on water quality problems. Changes in the hydrograph, in turn, will influence stream rehabilitation efforts, flood plain management and land use. With this paper, we begin to explore the potential hydrologic and stream morphologic responses resulting from a change to no-till farming practices.