ARS | Publication request: WATER BALANCE USING ELECTRICAL CAPACITANCE MEASUREMENTS IN A COASTAL SANDY SOIL

Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2005
Publication Date: July 30, 2005
Citation: Busscher, W.J., Bauer, P.J., Sadler, E.J., Evans, D.E., Strickland Jr, E.E. 2005. Water balance using electrical capacitance measurements in a coastal sandy soil [abstract]. Soil and Water Conservation Society Conference Abstracts, July 30-August 4, 2005, Rochester, New York. Available: http://www.swcs.org/en/swcs_international_conferences/2005_annual_conference/index.cfm?nodeID=7456&audienceID=1.

Technical Abstract: Water balance was calculated from Sentek capacitance sensors placed in cotton plots treated with conservation tillage (no surface tillage and non-inversion deep disruption of a hard layer). Sensors measured volumetric soil water content at 30 min time steps and 10 cm (4 in) depth intervals to 1 m (3.25 ft). Changes of soil water content were separated into infiltration, evapotranspiration, deep percolation, and runoff using rain gauge measurements and software designed specifically for this experiment. Cumulative infiltration was 75 to 85% of cumulative rainfall until the profile filled up with water. After that, it fell to 60% where it remained until the end of the growing season. Evapotranspiration was measured as the decrease in soil water content that did not drain lower into the profile. Evapotranspiration was greatest in the top foot and decreased exponentially below that. A two week dry spell in the middle of a very wet August caused the sandy soil to dry down in the root zone to the point that the plants were under stress, despite the fact that there was water deep in the profile. Even though the soil dried out easily and was disrupted deeply in the row, most water for plant growth came from the top foot.