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United States Department of Agriculture

Agricultural Research Service

Title: An Improved Automated Approach to Measuring Drainage with Equilibrium Tension

Authors
item Masarik, Kevin - U OF WI - MADISON
item Norman, John - U OF WI - MADISON
item Brye, Kristopher - UNIV. OF ARKANSAS
item Baker, John

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2003
Publication Date: March 3, 2004
Citation: Masarik, K.C., Norman, J.M., Brye, K.R., Baker, J.M. 2004. An improved automated approach to measuring drainage with equilibrium tension. Journal of Environmental Quality. 33:1152-1158.

Interpretive Summary: To evaluate the impact of farming practices on water quality it is necessary to obtain samples of the water that drains from the root zone toward groundwater. Two types of samplers have been used in the past, and both have problems. Passive samplers, with no suction applied, will collect water only during saturated flow. Suction samplers will collect water as long as their suction is greater than that of the surrounding soil, but because their suction exceeds that of the soil they overestimate the amount of drainage. We have designed and tested a suction sampler in which the suction is continuously and automatically adjusted to match the surrounding soil at the same depth as the sampler. This design produces accurate estimates of drainage and chemical leaching that were previously unavailable, and avoids the problems of previous samplers. It should be a valuable tool for both researchers and regulators interested in determining the impact of different types of land use practices on ground water quality.

Technical Abstract: To evaluate the impact of farming practices on water quality it is necessary to obtain an samples of the water that drains from the root zone toward groundwater. Two types of samplers have been used in the past, and both have problems. Passive samplers, with no suction applied, will collect water only during saturated flow. Suction samplers will collect water as long as their suction is greater than that of the surrounding soil, but because their suction exceeds that of the soil they overestimate the amount of drainage. We have designed and tested a suction sampler in which the suction is continuously and automatically adjusted to match the surrounding soil at the same depth as the sampler. This design produces accurate estimates of drainage and chemical leaching and avoids the problems of previous samplers. It should be valuable for determining the impact of land use practices on ground water quality.

Last Modified: 4/23/2014
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