Dr. Lentz's current research objectives include using polyacrylamide (PAM) or other surface active agents to inhibit infiltration into soil-lined channels; developing and evaluating such treatments into systems designed to reduce seepage from soil-lined water conveyance channels and increase furrow-irrigation water-application uniformity;(b)continued refinement of PAM erosion control application technologies and ascertaining long-term PAM effects on soil physical and chemical properties; (c) characterizing surface and subsurface soil water, solute and nutrient losses from furrow-irrigated fields, including effects of PAM-treatment and tillage on manured fields; (d) elucidating the relationship between furrow-stream water temperature and infiltration processes; and (e) determining the effect of meteorological factors on soil crust formation under sprinkler irrigation and evaluating methods for restoring crusted soils and/or ameliorating soil crusting effects on seedling emergence.
As a researcher at USDA-ARS Northwest Irrigation and Soils Research Laboratory, Kimberly, Idaho, Dr. Lentz developed and evaluated techniques using water-soluble and cross-linked PAM to inhibit water infiltration into soils; investigated the impact of low concentrations of polyacrylamide polymer (in irrigation water) and the effect of water quality, ie. total dissolved salts and sodium adsorption ratio, on furrow erosion and infiltration processes. Dr. Lentz identified a previously unrecognized quantitative relationship between polymeric flocculant concentrations and resulting flocculation dynamics and used this concept to develop a quantitative flocculation-based method for determining aqueous PAM concentrations as low as 100 ppb in irrigation water. A field protocol was developed, and a subsequent field evaluation and validation demonstrated the procedure's utility and precision for analysis of treated furrow-stream waters. Dr. Lentz has also developed a series of software programs that simplify and speed calculation of runoff, infiltration and solute/particulate runoff losses from monitored irrigated furrows. Current research focuses on advancing our understanding of those parameters that influence surface irrigation-induced erosion, defining soil-polymer interactions, and investigating processes and procedures that increase aggregate strength, mitigate soil crusting, and enhance seedling emergence.
While at the University of Minnesota, Dr. Lentz examined processes of concentrated-flow soil erosion (CFE) and atmospheric precipitation in complex agricultural landscapes and their influence on soil productivity. Lentz hypothesized and subsequently verified that CFE effects on soil property patterns differ with landscape, due mainly to differences in relative rill and interrill contributions, proclivity for channel 'wandering', and occurrence of depositional sorting. He also identified topographic parameters useful for predicting CFE severity in different landscapes. To explain topographic effects on CFE, Lentz hypothesized, verified, and modeled the effect of wind and low-relief topography on rainfall distribution in agricultural landscapes using an innovative field apparatus he designed.
Research at Oregon State University examined the correspondence of soil properties and classification units with sagebrush communities in southeastern Oregon. The study involved intensive soil and vegetation sampling, and employed several multivariate statistical analytical techniques.
Dr. Lentz's early work experience included a stint with the USDA Forest Service , where he evaluated and surveyed soil erosion and stream channel conditions within the Chemult District, Winema National Forest, Oregon. He also worked several years as a Consultant and NRCS Soil Scientist in Nevada, where he supervised field crews and participated in soil and vegetation surveys encompassing several million arid rangeland acres.
Lentz was an instructor at Carleton College Geology Department, Northfield, MN, where he developed and taught a 6-credit upper division course in soils with emphasis on soil genesis, morphology, and classification. He participated as a teaching assistant in wide range of soils courses at the University of Minnesota, St. Paul and Oregon State University, Corvallis, OR.
Updated: 6 April, 2004