Project Number: 6209-13000-013-14
Project Type: Specific Cooperative Agreement

Start Date: Jul 01, 2008
End Date: Nov 30, 2010

Objective:
The main objective is to evaluate impacts of agriculture (non-irrigated, irrigated) and rangeland on groundwater recharge in the Texas High Plains.

Approach:
The proposed study concentrates on the Texas High Plains Region. This study consists of two parts: (1) In the first part, six boreholes (up to 20 m deep) will be drilled and cores collected in land that has been subjected to different long-term tillage treatments at the USDA-ARS Conservation and Production Research Laboratory, Bushland, TX. A Geoprobe push drill (Model 6620DT, Salina, Kan) will be used to collect a series borehole core samples (up to 1.2 m long) contained within plastic sleeves for subsequent analysis. The soil core analyses include: soil water content, matric potential, and concentrations of chloride, sulphates, and nitrates. A chloride concentration peak displacement, relative to uncultivated native vegetation, will define depth of ion flushing and subsequently groundwater recharge. Recharge rates are related to land use and soil texture. We will correlate groundwater recharge information to long-term tillage treatments as corroborated with measured precipitation, surface runoff, and soil water content during the cropping season. In the second part, a similar study will be conducted in the Northern High Plains of Texas in which at least two locations each in Moore, Dallam, Sherman, and Hartley counties (Texas) will be selected for drilling and collecting soil cores. Efforts will be made to locate fields with long-term history on crop and tillage types. In addition, regional recharge rates will be estimated using groundwater chloride concentrations.