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United States Department of Agriculture

Agricultural Research Service

Research Project: Assessing Conservation Effects on Water Quantity and Quality at Field and Watershed Scales

Location: National Soil Erosion Research Lab

2012 Annual Report

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.

Review Publications
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.

Han, E., Heathman, G.C., Merwade, V., Cosh, M.H. 2012. Application of observation operators for field scale soil moisture averages and variances in agricultural landscapes. Journal of Hydrology. 444-445:34-50.

Halvorson, J.J., Gollany, H.T., Kennedy, A.C., Hagerman, A.E., Gonzalez, J.M., Wuest, S.B. 2012. Sorption of tannin and related phenolic compounds and effects on extraction of soluble-N in soil amended with several carbon sources. Agriculture. 2:52-72.

Halvorson, J.J., Gonzalez, J.M., Hagerman, A.E. 2012. Changes in Soluble-N in forest and pasture soils after repeated applications of tannins and related phenolic compounds. International Journal of Agronomy. DOI: 10.1155/2012/163054.2012.

Ritchey, K.D., Norton, L.D., Hass, A., Gonzalez, J.M., Snuffer, J.D. 2012. Effect of selected soil conditioners on soil properties, erosion, runoff, and rye growth in nonfertile acid soil. Journal of Soil and Water Conservation. 67:264-274.

Last Modified: 9/21/2014
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