Author
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Daniel, John |
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Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/10/2006 Publication Date: 4/1/2007 Citation: Daniel, J.A. 2007. Late-summer inflitration as affected by cropping and grazing management of winter-wheat pastures. Journal of Soil and Water Conservation. 62(2):103-109. Interpretive Summary: The economy of stocker calf production of the southern Great Plains depends on agricultural practices that use grazed winter wheat and associated summer management of the wheat fields, including chemical fallow and dual-cropping. However, limited information exists about the impact of these practices on infiltration. Infiltration rates under steady-state or saturated conditions were determined for the summer land-use practices chemical fallow and summer legumes, under grazed and ungrazed conditions using a rainfall simulator. Four pastures were planted in conservation winter wheat from 1998 to 2003. Two of the wheat pastures incorporated summer legumes (Korean Lespedeza and soybeans) while the other two pastures utilized chemical summer fallow. Pastures utilizing grazed winter wheat - summer chemical fallow had the lowest infiltration with 0.91 mm/min. Grazed and ungrazed summer legumes displayed similar infiltration rates (1.47 mm/min and 1.59 mm/min, respectively) with ungrazed chemical fallow producing a rate of 1.33 mm/min. The tap roots system of the summer legumes may have provided conduits for increased infiltration. This understanding can lead to strategies to reduce erosion and enhance capture of water resources. Technical Abstract: Agricultural practices that incorporate grazed winter wheat and associated summer management are vital to the rural economy of the southern Great Plains. In regions where high intensity, late summer storms prevail, limited information exists about the impact of these practices, including chemical fallow and dual-cropping summer fields, on infiltration. This study determined the effects of two winter wheat management strategies: winter wheat with summer chemical fallow (CF) and winter wheat with summer legumes (SL) simultaneously with two grazing treatments (grazed and ungrazed) on terminal or steady-state infiltration rates. The four pastures were planted in conservation winter wheat and grazed over winter when possible from November to March and March to May from 1998 to 2003. Two of the pastures incorporated summer legumes (Korean Lespedeza and soybeans) by direct seeding in March, and were grazed mid-July to September, while the other two pastures utilized chemical summer fallow. A rainfall simulator calibrated to represent late summer, high intensity (10 cm/hour) summer storms was used to determine terminal infiltration rates. Summer management and grazing practices associated with winter wheat were shown to significantly impact the terminal infiltration rate. Overall, the pasture utilizing grazed winter wheat with summer chemical fallow had the lowest infiltration with 0.91 mm/min. Grazed and ungrazed summer legumes displayed similar infiltration rates (1.47 mm/min and 1.59 mm/min, respectively) with ungrazed chemical fallow producing a rate of 1.33 mm/min. It is believed the tap roots system of the summer legumes provided conduits for preferential flow through the hard ground crust formed over a long dry summer. Understanding the mechanism of interaction between late summer storms and summer management practices will lead to formulation of larger scale mitigation strategies to reduce erosion and enhance capture of water resources. |
