262-6 Hygroscopic Water Content As a Surrogate for Clay Percentage in Proximal Soil Sensing.

See more from this Division: S01 Soil Physics
See more from this Session: Tomography and Imaging for Soil-Water-Root Processes: III
Tuesday, October 23, 2012: 10:15 AM
Duke Energy Convention Center, Room 237-238, Level 2
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Mark N. Wuddivira1, David A. Robinson2, Inmaculada Lebron2, Laëtitia Bréchet3, Melissa Atwell1, Sunshine De Caires1, Mike Oatham4, Scott Jones5, Hiruy Abdu6, Aditya Verma7 and Markus Tuller8, (1)Department of Food Production, The University of the West Indies, St. Augustine, Trinidad and Tobago
(2)Centre for Ecology and Hydrology, Environment Centre Wales, Bangor, United Kingdom
(3)Soil Team - Environmental Dynamics and Spatial Organizations, UMR INRA - AgroParisTech , Thiverval - Grignon, France
(4)Department of Life Sciences, University of the West Indies, St Augustine, Trinidad and Tobago
(5)Plants, Soils and Climate, Utah State University, Logan, UT
(6)Ags 160, Utah State University, Logan, UT
(7)University of Arizona Soil Water & Environmental Science, Tucson, AZ
(8)SWES Department, University of Arizona, Tucson, AZ
Geophysical techniques of proximal soil sensing provide non-invasive, rapid, cost effective and spatially exhaustive measurements of soil properties to understand plot scale soil heterogeneity. This is useful in precision agriculture, soil fertility, and soil and environmental contamination management. The benefits of rapid proximal sensing in reconnaissance surveys, however, can be weakened by the cost and tedious requirements of soil sampling and analysis of properties such as clay percentage required for the calibration of the geophysical signal. We hypothesized that hygroscopic water content whose determination does not require any special equipment and is time and cost efficient, can act as a pedotransfer function of clay percentage for efficient interpretation of soil spatial patterns based on proximal sensing. Using standard clays and soils of varying mineralogies from tropical (Trinidad, West Indies) and temperate (Arizona, USA) regions, we determined an accepted relative humidity value and re-equilibration time for the determination of hygroscopic water content in the laboratory. We found the relative humidity of 50 % (RH50) as the convenient point at which the change of hygroscopic water content with humidity is minimum and 2.5 days as the minimum re-equilibration time for the range of mineralogies. Hygroscopic water content measured at RH50 showed a strong linear dependence with clay percentage, suggesting that it has good potential to act as a pedotransfer function to estimate clay percentage for efficient reconnaissance surveys.
See more from this Division: S01 Soil Physics
See more from this Session: Tomography and Imaging for Soil-Water-Root Processes: III