Water Resources Research Act Program

Details for Project ID 2008VT35B

Soil phosphorus landscape variability and soil mapping in a stream

Institute: Vermont
Year Established: 2008 Start Date: 2008-03-01 End Date: 2009-02-28
Total Federal Funds: $7,390 Total Non-Federal Funds: $74,342

Principal Investigators: Donald Ross, Eric Young

Project Summary: Sediment and associated phosphorus (P) inputs from agriculture, riparian stream bank erosion, and fluvial processes are thought to be major contributors of P loading to Lake Champlain. Soil properties impose important constraints on the transport and cycling of P in riparian zones. In many Vermont (VT) stream corridors, stream bank erosion itself can be a significant source of P. Research in progress indicates that soil P availability varies significantly among floodplain map units in VT. Thus, soil variability and the associated P content of riparian zones are both critical for developing tools to improve water quality. Our project will quantify and map relationships among soil map unit properties and P availability in a riparian corridor located in the Northern Lake Champlain watershed. The objectives of the project are to: (i) Describe the spatial variability of P and map unit properties among the soils, and (ii) Evaluate the extent of sampling/site characterization needed to achieve a given level of map unit accuracy and expected soil P content within a defined riparian corridor section. The research will also determine the adequacy of the soil survey to depict soil variability and P contents, and identify appropriate levels of soil characterization for modeling and management efforts. A site will be selected to encompass a broad range of floodplain map units and to provide the Vermont Agency of Natural Resources with data to support their management efforts. Objective one will be met by remapping the soils at the site using traditional and geostatistical methods. After the soils have been remapped, a grid-based soil sampling approach with nested subsampling will be applied to capture small- and larger-scale variation in chemical and physical properties. Soil P pools, organic carbon, minerals, texture, and other properties will be analyzed at the UVM Agricultural and Environmental Testing Lab. Predictive maps (ordinary kriging) of P pools, drainage, texture, organic carbon and other covariates will be developed. Additional laboratory experiments will evaluate organic and inorganic P solubility in subsamples from the predominant map units. Results will also include soil series-specific estimates of P content and a statistical analysis of soil properties influencing P availability. Comparisons among the soil survey map, the high order remapping, and the interpolated maps will assess map unit accuracy with respect to different sampling schemes. Results from this project will be integrated with water quality management efforts in the Northern Lake Champlain Basin to help guide prioritization and implementation of best management practices.