Author
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PALTINEANU, IOAN - PALTIN INTERNATIONAL INC. |
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Starr, James |
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Submitted to: Journal of Environmental Science and Health
Publication Type: Book / Chapter Publication Acceptance Date: 7/21/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Water is the major vehicle for moving chemicals through and over soils. Reliable predictions of the environmental impact of different management practices require accurate measures of vadose zone (aerated region of soil above the permanent water table) soil water content in both space and real-time. There is a continued need for better methods and techniques to perform accurate, real-time nearly continuous soil water measurement at specific depths, with minimal soil disturbance, and covering field scale areas with few cables and data loggers. Recently developed instrumentation that utilize the apparent dielectric constant of the soil to measure the soil water content are increasingly used as part of permanent or semi-permanent soil water monitoring systems for assessing real-time soil water dynamics in the vadose zone. This chapter reviews the theory and instrumentation of these methods, and presents several case studies that illustrate the kinds of information that can be obtained, including: year around and multi-year real-time soil-water data; apparent water holding capacity; onset of water stress; temporary loss of free water by freezing; relation of evapotranspiration to soil water dynamics under corn and tomatoes; and assessment of upward and downward water movement above the water table. Technical Abstract: Water is the major vehicle for moving chemicals through and over soils. Reliable predictions of the environmental impact of different management practices requier accurate measures of vadose zone soil water content in both space and real-time. Recently developed instrumentation that utilize the apparent dielectric constant of the soil to measure the soil water content are increasingly used a spart of permanent or semi permanent soil water monitoring systems for assessint real-time soil water dynamics in the vadose zone. This chapter reviews the theory and instrumentation of these methods, and presents several case studies that illustrate the kinds of information that can be obtained, including: year around and multi-year around real-time soil-water data; apparent water holding capacity; onset of water stress; temporary loss of free water by freezing; relation of evapotraspiration to soil water dynamics under corn and tomatoes; and assessment of upward and downward water movement above the water table. |
