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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Agricultural Engineering

First Advisor

D. W. DeBoer


Groundwater contamination by leaching of agricultural chemicals is an environmental and economical concern for crop producers. A field study was initiated to investigate the effects of crop and tillage management on water and chemical movement through the soil profile. An automatic sampling system was designed to continuously monitor soil water movement and sample soil water during leaching events. The system includes sampling and monitoring equipment installed laterally from vertical access holes at 60, 120 and 180 cm (24, 48 and 72 in.) depths. Soil water potential data were collected hourly and automatically transferred daily to a personal computer via modem. Soil water potential and rainfall depth were used to initiate the sampling process and automatically sample soil water from unsaturated or saturated soil. The samplers were made from materials that minimize the adsorption of organic compounds to ensure the integrity of the water samples for analysis. The system performed according to design specifications when leaching events occurred and collected continuous soil water potential data for more than a year. The key to controlling chemical leaching is understanding the chemical transport process through the unsaturated zone. To meet this need, the Water Resources Institute at Brookings, South Dakota started an agricultural chemical leaching study in 1988. The main goal of the study is to determine the effects of crop and tillage management on pesticide and water movement through the unsaturated zone. In order to achieve this goal, an event-actuated soil water sampling system was designed to automatically collect soil water samples for chemical analysis at various positions in the soil profile. The objective of this thesis project was to design, construct, install and test the soil water sampling system for this agricultural chemical leaching study.

Library of Congress Subject Headings

Soils -- Leaching

Groundwater -- Sampling

Groundwater -- Quality



Number of Pages



South Dakota State University