Location: National Soil Erosion Research2012 Annual Report
1a. Objectives (from AD-416):
Objective 1. Advance the knowledge and improve mathematical representation of physical and biogeochemical processes affecting sediment, nutrient, and pesticide losses in runoff. Subobjective 1.1. Quantify surface and subsurface hydrologic effects on runoff chemical transport and ephemeral gully erosion. Subobjective 1.2. To identify practices that will optimize the benefits of no-tillage, while minimizing the risk of P losses via runoff, without sacrificing crop productivity. Subobjective 1.3. Identify practices to optimize drainage while maximizing nutrient removal efficiency. Objective 2. Protect off-site water quality by developing methods to reduce pollutant losses from agricultural fields and watersheds. Subobjective 2.1. Develop a BMP (Best Management Practice) to reduce nutrient and pesticide delivery from landscapes to drainage systems and water bodies and reduce greenhouse gas emissions. Subobjective 2.2. Test the impact of established and new conservation practices at the field and watershed scale. Subobjective 2.3. Determination of optimal BMPs for control of runoff, sediment, and chemical losses from agricultural fields and watersheds, under existing and future climates. Objective 3. Improve soil erosion and water quality models for better assessment and management of cropland, forestland, and other managed lands. Subobjective 3.1. Improve our ability to predict soil erosion and water quality. Subobjective 3.2. Develop techniques that enhance field-to-watershed model parameterization for improved hydrologic model predictions. Subobjective 3.3. Develop methods to optimize chemical monitoring parameters to minimize costs and uncertainties associated with characterizing selected endocrine disrupting chemicals in artificially drained landscapes.
1b. Approach (from AD-416):
Laboratory studies will be used to gain process-level understanding on the effects of topographic driven surface water convergence and soil hydraulic gradient driven subsurface flow on sediment and chemical loadings. Landscape attributes affecting convergence of surface and subsurface flows will be used to validate the lab findings on conditions for channel initiation and chemical transport. To identify practices that optimize the benefits of no-till while minimizing risk of P losses, laboratory experiments will be used to test a large array of fertilizers and production practices. Plot scale experiments will be used to evaluate practices over a 5 to 10 yr period as they relate to soil and water quality. To identify practices that optimize drainage while maximizing nutrient removal, lab and streamside fluvaria will be utilized. Treatments of various materials including gravel and woodchips below stream sediment will be tested, as will use of various heights of sediment dams, to reduce nutrient losses in stream water. Controlled drainage on tile drained fields to optimize soil moisture status to reduce excess loss of nutrients, in combination with a soil amendment of flue gas desulfurization (FGD) gypsum will be evaluated. This project will continue to monitor runoff and water quality in subwatersheds of the St. Joseph River (SJR) in northeastern Indiana, and also conduct ecological studies through an SCA with Indiana-Purdue University Ft. Wayne and a cooperative project with ARS-Columbus. Detailed flow and pollutant data in the SJR subwatersheds are available from 2003-present, allowing for both uncalibrated, calibration, and validation studies with a number of watershed hydrology, sediment, and water quality models. The models can also be applied in a forecasting mode, to examine impacts of widespread or targeted placement and implementation of various land management practices (e.g. conservation tillage, different crop rotations, buffer strips, etc.) on predicted runoff and pollutant losses. Use of information from Global Environment Models will be downscaled to develop modified climate inputs to the Water Erosion Prediction Project (WEPP) model. In-house and cooperative erosion model development, testing, and validation efforts will be conducted. Work will include maintenance of WEPP, including model scientific code, user interfaces, model databases, and user support. Cooperative efforts on development of a combined wind and water erosion model will be continued. A new WEPP-Water Quality model will be developed which will also allow examination of the impacts of projected future climate change on runoff, sediment, and chemical losses and how management practices to reduce these losses may change. Geostatistical scaling techniques will be applied and evaluated to allow linkage of various soil parameters (i.e., hydraulic conductivity, porosity) across scales ranging from a few hectares to subbasins of 10,000+ ha. Loading of endocrine disruptors and selected metabolites to the SJR will be examined for significant relationships between analytes. Through statistical correlation analysis, potential surrogate analytes will be identified.
3. Progress Report:
Substantial progress has been made on laboratory and field studies on this new project. A lab study on the effects of surface topography under a drainage condition was completed. A new laboratory recirculating flume using plastic tubing was constructed and has been undergoing testing for chemical movement (bromide tracer) from a saturated sand bed into overflowing water. In the National Soil Erosion Research Laboratory fluvarium, sediments with high hydraulic conductivity were tested to examine their impacts on chemical desorption and adsorption. Data collection was accomplished in Indiana and Kansas at field sites being used to study gully characteristics and development. Plots were established at the Throckmorton Purdue Agricultural Center to study how minimize soluble phosphorus losses from no-till farming. Soils from these plots have also been collected for use in a companion laboratory study. Field plots were established at the Purdue Davis Agricultural Center to study the effects of controlled drainage and gypsum soil amendment on crop production and water quality. Water flow and samples for nutrient and herbicide analyses were collected from field, ditch, and stream sites in the Upper Cedar Creek Watershed (UCCW) in northeastern Indiana. Weather in 2012 has been extremely hot and dry, thus number of water samples for analysis have been much less than in previous years. Three additional soil moisture and meteorological stations have been installed within the UCCW. Measured field to watershed scale soil moisture data has been obtained and processed for the 2011 European Space Agency SMOS remotely sensed soil moisture project that covers the UCCW. Validation of SMOS algorithms is in progress. Significant progress toward calibration/validation of Agricultural Policy Environmental EXtender (APEX) and application of the model to assess the impacts of conservation practices at the field scale has been made. Natural Resources Conservation Service (NRCS) is currently implementing and using a version of Wind erosion Prediction System (WEPS) containing the WEPP hydrology/erosion code. Cooperative projects are underway with the Forest Service, Washington State University, Iowa State University, and the University of Iowa on new WEPP interfaces. The St. Joseph River Watershed Conservation Effects Assessment Program Watershed Assessment Study (CEAP WAS) has been selected as one of two benchmark watersheds to be used for a multi-Agency effort to assess the impacts of conservation practices on environmental quality at the watershed scale. This will be an intensive 1-yr effort, compiling monitored water quality and quantity data, ecological assessment data, cropping system attribute data, as well as field and watershed scale modeling efforts to provide the other agencies with information on the effectiveness of current conservation practices, and how those agencies may better target conservation practices in the future.
1. Development of a new conservation practice standard with Natural Resources Conservation Service (NRCS). In the young glacial till landscape of the upper Midwestern U.S., closed depressions – known locally as potholes, are widely pervasive. Surface drainage water from potholes will collect at the lowest spot in the pothole, and will keep the area too wet for farming, even when using standard subsurface tile draining the field. Therefore, most potholes that are farmed are drained with subsurface tile, but also have supplemental drainage from a tile riser that extends vertically to the soil surface and above the soil surface. A tile riser is a pipe with ½” – ¾” holes drilled in the sides. ARS researchers at West Lafayette, Indiana identified the extent of potholes within a watershed as being directly related to the concentrations or loads of nutrients lost from the watershed. An alternate practice, called a blind inlet, was researched to provide greater filtration of surface water from potholes. Loads of P can be decreased by about 78% when drained with a blind inlet compared to a tile riser, and N loads can be decreased by greater than 50% when drained with the blind inlet. Decreased nutrient (N and P) losses to runoff water translate to savings to farmers as well as improved water quality. In 2012, ARS scientists from the National Soil Erosion Research Laboratory have worked with NRCS to develop a conservation practice standard, and NRCS in Indiana is now offering blind inlets as a cost-sharable practice through the Environmental Quality Incentives Program (EQIP). State NRCS offices in Ohio, Wisconsin and Iowa have also shown interest in the practice.
2. St. Joseph River Watershed selected as the first pilot in the USDA Agency Priority Goal Project. The St. Joseph River Watershed Conservation Effects Assessment Program Watershed Assessment Study (CEAP WAS) has been selected as one of two benchmark watersheds to be used for a multi-Agency effort to assess the impacts of conservation practices on environmental quality at the watershed scale. The Agency Priority Goals (APG) project is a collaboration between Natural Resources Conservation Service (NRCS), Farm Service Agency, U.S. Forest Service and ARS to provide a cost/benefit analysis to conservation practices at the 12-digit Hydrologic Unit Code (HUC) level. Based on the scale, resolution, and quality of the data collected in the St. Joseph River Watershed CEAP WAS, ARS researchers at the West Lafayette, Indiana were contacted by NRCS headquarters as the first watershed requested to participate in the APG project. This will be an intensive 1-yr effort, compiling monitored water quality and quantity data, ecological assessment data, cropping system attribute data, as well as field and watershed scale modeling efforts to provide the other agencies with information on the effectiveness of current conservation practices, and how those agencies may better target conservation practices in the future.
3. Wind-driven rainfall consideration improves erosion prediction. The Water Erosion Prediction Project (WEPP) model is a widely available and used method to predict soil erosion by water. Although the model is process based, it does not explicitly model the effect of wind driven rain (WDR) on erosion. ARS researchers at West Lafayette, Indiana collaborated with researchers from Turkey and Belgium and conducted experiments to collect data sets to evaluate the magnitude of this effect under various wind speeds and two directions to the wind, either slope facing into the wind or down wind. The interrill erosion process in WEPP could be modified to better describe an effective rainfall intensity using three simple terms. These included the angle of rain incidence, the effective energy of the rain hitting the surface both falling vertically and the effective angle on the slope. The direction of the slope did not improve predictions because it was effectively accounted for by the angle of rain incidence. The research benefits the erosion modelling community because now there is a mechanistic description of wind-driven rain to account for the wind effects on interill erosion.
4. Application of observation operators for field soil moisture assessment. Scale differences between ground-based and remotely sensed soil moisture observations has been an issue for validation of remote sensing data, soil moisture data assimilation and calibration of hydrologic models. ARS researchers at West Lafayette, Indiana, Beltsville, Maryland, and Purdue University researchers demonstrated the linkage between two different scales of soil moisture estimates by upscaling single point measurements to field averages for representing field-scale agricultural areas (~ 2 ha) located within the Upper Cedar Creek Watershed in northeastern Indiana. By analyzing the statistical distribution of the field meaured soil moisture data, measurements made at a single point can be interpreted or up-scaled to the field scale. These results impact scientists and other users attempting to assess soil moisture using remotely-sensed information and compare it to field-scale point measurements.
Erpul, G., Gabriels, D., Norton, L.D., Flanagan, D.C., Huang, C., Visser, S. 2012. Mechanics of interrill erosion with wind-driven rain. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3280.