Author
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Daniel, John |
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Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/1/1999 Publication Date: N/A Citation: N/A Interpretive Summary: A three year study (1994 to 1996) utilizing four 4-acre watersheds was done to determine the impact of wheat tillage practices on recharge to shallow groundwater. Each watershed has 3 groundwater wells which allowed monthly water table measurements. The tillage practices examined were no-till, moldboard, and sweeps which represent typical practices for Redland Prairie region of Oklahoma, Texas and Kansas. A native grass watershed was used for control. Results show native grass conditions have the greatest contribution to the groundwater during years of average and above average rainfall, respectively. However, during years with below average rainfall, no active recharge was found. The watershed with winter wheat tillage practices had significantly lesser recharge amounts for years with average and above average rainfall. But, the tilled watersheds had some recharge had occurred during below average rainfall. This recharge is due to fallow practice during summer. Technical Abstract: A three year study (1994 to 1996) utilizing four 4-acre watersheds was done to determine the impact of wheat tillage practices on recharge to a shallow unconfined groundwater system. Each watershed was equipped with 3 groundwater wells which allowed monthly monitoring of water levels. The tillage practices examined were no-till, moldboard, and sweeps which represent typical practices for Redland Prairie region of Oklahoma, Texas and Kansas. A native grass watershed was used for control. Two methods of quantifying recharge from fluctuating water table levels were used - an averaged index and active monthly recharge. Results show native grass with the highest index (.7) followed by moldboard (.6), sweeps (.2) and no-till (.06). Native grass conditions have the greatest contribution to the groundwater with 9.78 inches and 18.41 inches of water for average and above average rainfall, respectively. However, during a year with below average rainfall, no active recharge was found. The watersheds with different tillage practices had lesser recharge amounts. With average annual precipitation (33 inches), moldboard recharged 7 inches, no-till 1.5 inches, and sweeps 1.3 inches. During above average rainfall (39.8 inches), moldboard recharged 8.2, no-till 4.6 and sweeps 4.3 inches, and during below average precipitation, moldboard recharge 4.1, no-till 1.7, and sweeps .8 inches. This recharge is attributed to fallow practice during summer and low evapotranspiration during the fall and early winter. |
