ONE-STEP INFLOW/OUTFLOW CELL TO DETERMINE SOIL HYDRAULIC PROPERTIES

THE RELATIONSHIP AMONG WATER POTENTIAL, HYDRAULIC CONDUCTIVITY, AND WATER CONTENT (P-K-O) ARE SOME OF THE MOST COMMONLY SOUGHT SOIL PHYSICAL PROPERTIES. PREDICTION OF WATER AND SOLUTE MOVEMENT IN BOTH AGRICULTURAL AND ENVIRONMENTAL SITUATIONS IS ULTIMATELY PREDICATED UPON AN ADEQUATE EXPERIMENTAL DESCRIPTION OF POROUS MEDIA. A RAPID AND ACCURATE METHOD TO DETERMINE THESE RELATIONSHIPS WOULD FIND WIDE APPLICATION IN AGRICULTURAL, ENVIRONMENTAL, AND ENGINEERING APPLICATIONS. BECAUSE MUCH OF THE WATER AND SOLUTE FLOW INFORMATION SOUGHT TYPICALLY OCCURS WITHIN THE EXPECTED RANGE OF OUR PROPOSED ONE-STEP PRESSURE CELL (0 TO 1 BAR), A LARGE PORTION OF THE NECESSARY HYDRAULIC INFORMATION POTENTIALLY CAN BE OBTAINED WITH ONE AUTOMATED MEASUREMENT. WE PROPOSE TO TEST AND REFINE A WORKING PROTOTYPE ONE-STEP INFLOW/OUTFLOW CELL TO OBTAIN DATA TO ESTIMATE P-K-O. THE DESIGN IS ESSENTIALLY A MODIFIED TEMPE CELL EQUIPPED WITH A SURFACE TENSIOMETER, POROUS NYLON MEMBRANES, AND PRESSURE TRANSDUCERS TO AUTOMATE DATA COLLECTION. IN ORDER TO PROVE THE CONCEPT, WE MUST ALSO TEST THE FEASIBILITY OF ANALYZING THISNEW INFORMATION. THE PARAMETERS OBTAINED MUST BE COMPARED TO OTHER METHODS. DATA ANALYSIS WILL INCLUDE DIFFUSIVITY/CONDUCTIVITY ESTIMATES USING SEVERAL METHODS AVAILABLE IN THE LITERATURE. THESE ARE DISCUSSED IN MORE DETAIL IN THE PROPOSAL.