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ARS Home » Research » Publications at this Location » Publication #105722
Title: CONTINUOUS IN SITU SOIL MOISTURE MONITORING IN SUPPORT OF THE MISSISSIPPI BASIN CARBON PROJECT

Author
item HUNTINGTON, T - USGS
item Kramer, Larry
item MARKEWICH, H - USGS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/12/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Soil water content and potential are being monitored continuously in soybean fields in Mississippi and Iowa on upland soils developed in loess parent material. These measurements are being made in support of the Mississippi Basin Carbon Project (MBCP). A primary objective of the MBCP is to quantify the interactive effects of climate, land-use, erosion, and sedimentation on carbon storage. In Iowa and Mississippi, soil moisture deficit during the growing season has frequently been shown to limit crop production and associated residue incorporation into soils. Climate change resulting in increased summer dryness would likely decrease soil carbon storage because the associated decrease in residue inputs would be greater than transient inhibition of SOM decomposition due to soil water deficit. Water content is measured with a Campbell Scientific Inc. (CSI) Model 615 water content reflectrometer that uses the principle of time domain reflectrometry. Water potential is measured with a CSI Model 229 heat dissipation probe using a thermocouple and line heat source embedded in a porous ceramic cylinder designed to approximate the pore size distribution and geometry of a silt loam soil. Using the probes together permits the construction of hysteretic soil moisture release and uptake curves. Soil water data is used for modeling soil respiration during the growing season and may be used for modeling plant growth, soil organic matter (SOM) decomposition, and soil erosion. Analysis of temporal variability indicates that both probes respond rapidly to transient changes in soil moisture and are sensitive over a broad range of soil water content and soil water potential.