UNDERSTANDING THE PHYSICAL CONSTRAINTS OF SOIL STRUCTURE AND ITS INFLUENCE ON SOIL HYDRAULIC PROPERTIES

Abstract

This research explores the application of multistripe laser triangulation (MLT) three-dimensional scanning to better understand soil structural constraints and predict soil hydraulic properties. Study sites for this work were located in Northeast Kansas, and split between the University of Kansas Field Station and the Kansas State Konza Prairie Biological Station. At each site, descriptions were made, soils were sampled, and profiles were scanned in situ using MLT. This thesis addressed two questions. First, do physical properties constrain the expression of soil structure? Particle-size distribution, organic carbon, and coefficient of linear extensibility were the physical properties examined and each appeared to constrain various aspects of soil structure. Second, can the soil hydraulic properties of field capacity, permanent wilting point, inflection point, and saturation water contents, saturated hydraulic conductivity, and effective porosity be predicted from MLT-quantified metrics of soil structure? Soils were equilibrated to a range of pressure potentials to generate water retention data for each site and hydraulic parameters were estimated from curves fitted to the data. These parameters were regressed against soil structural metrics to create structure-based pedotransfer functions for hydraulic properties. Results indicated that soil structural metrics can be used to successfully and accurately predict soil hydraulic properties.