Location: National Soil Erosion Research2013 Annual Report
1a. Objectives (from AD-416):
1) Mitigate the impacts of soil drainage conditions on soil quality, soil erodibility, nutrient cycling and pesticide dynamics. 2) Develop control practices for soil erosion and specifically ephemeral gully erosion. 3) Optimize the benefits of innovative farming systems, including biofuel production, on soil water dynamics, soil and water quality, soil erosion and greenhouse gas emissions.
1b. Approach (from AD-416):
Conduct laboratory and field experiments to quantify the impact of soil drainage on soil and water quality, erodibility, nutrient cycling and pesticides dynamics. Develop practices to control soil ephemeral gully and other forms of water erosion. Develop through experimentation new innovative farming systems that reduce greenhouse gas emissions while optimizing benefits to production, soil and water quality and reducing erosion.
3. Progress Report:
Experiments are underway, using the biogeochemical reactors, to quantify the short-term water ponding effect on nutrient dynamics and pesticide transformation. Using gypsum as soil amendment to mitigate the negative impacts of a reducing condition from water ponding is being evaluated. Effects of soil saturation and drainage on soil cohesion, aggregate stability and erodibility are quantified using the fluidized bed procedure and mini-flumes. Soil saturation treatments included the time under saturation, hence a measure of aging effect, and the cohesion developed was compared to the cohesion from soil drainage. Results showed that soil drainage has a much greater impact on the development of soil cohesion and rill erodibility than water ponding, or aging. A journal manuscript has been accepted. To quantify soil hydrology at different land scape positions, an extensive number of soil samples have been collected at three large scale field sites at the Upper Cedar Creek Watershed to determine physical and hydraulic properties according to standard lab procedures. In addition, in situ soil moisture measurements were obtained over a 3-month period in all 3 fields at 2 depths (5 and 20cm) to determine the spatial variability of soil moisture and infiltration/drainage characteristics as affected by different management practices. All soil samples have been processed; all soil moisture data has been processed and verified with all physical, hydraulic and moisture data stored in a data base. The initial phase for estimating geospatial surface and subsurface characterization of soil physical and hydraulic properties based on observational data is in progress. To evaluate hydraulic retention and chemical retention efficiency of potential blind inlet filter media, sorption isotherms were conducted using shreaded used tires, or tire chips, as a media to sorb atrazine and nitrate. These studies now include the sorption behaviors of phosphate and glyphosate. At Purdue Davis Farm, control drainage plots were placed with and without flue gas desulfurization (FDG) gypsum applied. Soil samples were collected before treatments and analyzed for chemical and physical properties. Lysimeters were installed and water samples were collected on the 4th week of July for chemical analysis. Plant samples will be collected during flowering and at harvest and grain samples during harvest. Likewise, soil samples will be collected after harvest to compare to the changes before and after treatments.
1. Soil drainage enhances soil cohesion and reduces rill erodibility. Temporal variations in soil erosion resistance are often the result of decrease in soil cohesion due to physical disruption followed by a regain of soil cohesion with time which is often called aging, stabilization or consolidation. To quantify soil cohesion development, ARS researchers at West Lafayette, IN, and cooperators from Brazil conducted a laboratory study with soils samples subjected to different durations of aging and drainage. The study used the fluidized bed method to measure soil cohesion and a flume experiment to measure the critical shear stress and rill erodibility with soils subjected to different experimental treatments. Changes in soil cohesion due to aging and drainage state were successfully detected by the fluidized bed technique. When soils were aged at field capacity (drained condition), the resulting cohesion was on average 3.13 times higher than that measured when aging was done at saturation. This indicates that soil drainage is beneficial to cohesion development and a reduction in soil erodibility, therefore, it can be used as a conservation practice for erosion control.
2. Pesticides losses from agricultural fields. Atrazine and glyphosate are the most widely used herbicides in the Corn Belt and listed in the Environmental Protection Agency (EPA) Drinking Water Standards and Health Advisories as drinking water contaminants. ARS researchers at West Lafayette, IN have been monitoring pesticides in drainage ditches at the Cedar Creek watershed which is within the St. Joseph River Watershed that serves as the source area for water supply to the city of Ft. Wayne. Results show 75% of glyphosate and 89% of atrazine losses occurred in May and June with only 6% of the atrazine samples exceeding the EPA Maximum Contaminant Level (MCL) of 3 Mg/L, while all glyphosate samples were below the 70 Mg/L MCL. This research shows that drinking water suppliers can strategically implement remediation in May and June to minimize the risk of pesticides in drinking water.
Stott, D.E., Karlen, D.L., Cambardella, C.A., Harmel, R.D. 2013. A soil quality and metabolic activity assessment after fifty-seven years of agricultural management. Soil Science Society of America Journal. 77(3):903-913.