Author
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Daniel, John |
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Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings Publication Acceptance Date: 5/1/2003 Publication Date: 7/27/2003 Citation: Daniel, J.A. 2003. Impact of grazing winter wheat on runoff. In: Proceedings of American Society of Agricultural Engineers. July 27-30, 2003, Las Vegas, NV. p. 1-11. Interpretive Summary: With the prospect of water shortages due to increased population and industrial demands, providing an adequate supply of potable water to accommodate predicted future water needs in large urban areas, while maintaining supplies for agricultural production, is a primary issue to be addressed in the 21st Century. This study determined the percent loss of precipitation associated with late summer storms as surface runoff from grazed winter wheat pastures. All the pastures utilize one of the four following summer management strategies: grazed or ungrazed winter-wheat with summer fallow or grazed or ungrazed winter-wheat with summer legumes. Surface runoff measurements generated by a rainfall-simulator representing late summer storm events were used with replicated grazed and ungrazed paired plots on four pastures planted in no-till winter wheat. The pastures were either grazed from November to May or ungrazed, and utilized two summer management strategies (summer fallow or summer legumes). Results show that for simulated late summer storms, 70% of the precipitation is lost as runoff with plots utilizing grazed winter wheat and summer fallow, while the grazed winter wheat with grazed summer legumes lost 23 percent. Ungrazed winter wheat plots, using either fallow or summer legume management, had runoff losses that ranged from 5 to 11 percent. Loss of precipitation as runoff is considered undesirable in agriculture because the water is not available for plant utilization. However, catchments, such as surface impoundments and ponds, are advantageous by restricting downstream movement of water resources and potentially-eroded sediment and providing immediate relief to livestock and wildlife in the dry period. Technical Abstract: With the predicted future water needs, a primary issue to be addressed in the 21st Century is providing an adequate supply of potable water in large urban areas. However, even with increasing urban population and industrial demands, maintaining water supplies for agricultural production is also a major concern. The agricultural economy in the southern Great Plains, include practices, which incorporate grazed winter wheat. While water quality information about these practices is present, data is limited about their impact on downstream water resources. This study examined the precipitation-surface water partitioning from four summer management strategies, which utilize winter wheat: grazed (gWWF) and ungrazed (uWWF) winter-wheat with summer fallow and grazed (gWWSL) and ungrazed (uWWSL) winter-wheat with summer legumes. Four pastures planted in no-till winter wheat and were either grazed from November to May or ungrazed, and utilized two summer management strategies (summer fallow or summer legumes). Surface runoff from replicated grazed and ungrazed paired plots were measured utilizing a rainfall-simulator, which generated a short duration (15 minute), high intensity (10 cm/hour late summer storm). Results indicate the gWWF practice that 70% of the precipitation is lost as runoff, while the gWWSL practice loses 23%. Precipitation losses as runoff from the ungrazed plots ranged from 5 to 11%. Loss of precipitation as runoff is considered undesirable in agriculture because the water is not available for plant utilization. However, catchments, such as surface impoundments and ponds, are advantageous by restricting downstream movement of water resources and potentially-eroded sediment and providing immediate relief to livestock and wildlife in the dry period. |