1a. Objectives (from AD-416):
Streams in the Salt River Basin in northeastern Missouri have a well-documented history of herbicide and sediment contamination problems and are representative of the Central Claypan Areas (Major Land Resource Area (MLRA) 113), which encompass 3.3 million ha in northeastern Missouri and south-central Illinois. Research has shown this area to be the most vulnerable within the Corn Belt to transport of atrazine by surface runoff. The key hydrologic feature of soils within MLRA 113 is the presence of a subsurface claypan with smectitic mineralogy. Soils with smectitic mineralogy and the presence of argillic horizons or fragipans that also serve as restrictive layers will have similar hydrology to that of claypan soils. This potentially extends the applicability of this proposed research to an area of over 18 million ha throughout the Midwest, including the following MLRAs: 106 (Nebraska and Kansas Loess-Drift Hills), 109 (Iowa and Missouri Heavy Till Plain), 112 (Cherokee Prairies), and 114 (Southern Illinois and Indiana Thin Loess and Till Plain, Western Part). Objective 1: Conduct field- and watershed-scale studies to assess the contribution of surface runoff, interflow, and groundwater recharge to contaminant transport in claypan watersheds. 1: Measure interflow transport of atrazine and nitrate (NO3-) at the landscape scale. Objective 2: Develop and assess the effectiveness of management practices and bio- and phytoremediation technologies for reducing hydrologic transport of agricultural contaminants. 2a: Assess the efficacy of vegetative buffer strips for reducing the transport of dissolved-phase and sediment-bound organic contaminants (herbicides and veterinary antibiotics). 2b: Compare the impact of bioenergy cropping systems to conventional cropping systems on sediment, nutrient, and herbicide transport. 2c: Assess the soil and water quality impact of a field-scale precision agriculture system on sediment, nutrient, and herbicide transport. Objective 3: Improve watershed models for targeting conservation practices on the landscape and to better assess the aggregate impact of field- and watershed-scale management practices on surface water quality. 3a: Improve the capability of models to simulate sediment, nutrient, and herbicide transport from diversified cropping systems, including bioenergy crops. 3b: Develop methods to target BMPs to vulnerable areas. Objective 4: Improve watershed management and ecosystem services through long-term observation, characterization, delivery, and application of information from agricultural watersheds and landscapes. 4a: Conduct long-term water quality monitoring and characterization of agricultural watersheds and landscapes to assess trends and cause-effect relationships in contaminant transport. 4b: Multi-Location Project: Estimate the impacts of projected climate change on regional water availability and quality (including watershed sediment yield), across diverse physiographic regions of the U.S., and their associated implications for conservation needs and agricultural productivity.
1b. Approach (from AD-416):
The impact of alternative and prevailing crop management systems on soil and water quality will be studied at field, farm and watershed scales. This research will focus on assessing water quality from plot to watershed scales, coordinated with soil quality assessments at plot and field scales. It also focuses on the development of tools and techniques to quantify the impact of implementing conservation practices within a watershed in the most economically efficient manner to achieve sustainable and targeted reductions of nutrients, sediment, and herbicide loadings to the region’s streams, rivers, and impounded waters. The proposed research will also examine the environmental effects of bioenergy crops compared to conventional grain crop production and assess the potential benefits of targeting bioenergy production to vulnerable landscape areas. Lastly, the nation-wide ARS watershed network will utilize its decades-long weather and stream discharge data to estimate the impacts of projected climate change on regional water availability across diverse physiographic regions of the United States, and their associated implications for conservation needs and agricultural productivity.
3. Progress Report:
In 2012, the Salt River monitoring network was reduced from 7 to 5 sites, and all sites were installed by early April. Sites were chosen on the basis of whether or not they supported on-going ARS research and the Natural Resources Conservation Service Mississippi River Basin Initiative (MRBI) project within Goodwater Creek Experimental Watershed (GCEW). Three new sites, established in 2011, located in the Little River Drainage District of southeastern Missouri have been used to assess nutrient and sediment transport in this intensive agricultural area. Results from the first year indicate greater nutrient transport than occurs in GCEW; however, nitrogen concentrations were generally low (e.g., total nitrogen was <3.0 mg/L for all samples) while phosphorus was consistently high (generally >0.20 mg/L). These first-year results were presented at a MRBI meeting in Stoddard County, MO (July 2012). Because of the exceptionally dry conditions this year, ARS researchers at Columbia, MO Water Quality Lab received a total of only 311 water samples (compared to >1500 in recent years). Conservation Effects Assessment Project (CEAP) activities in 2012 included completion of 4 full years of streambank erosion data collection at 34 sites in Crooked and Otter Creek watersheds (located within the Salt River Basin) and continued water quality monitoring within the Long Branch Creek watershed (which includes GCEW). Tentative sites for the interflow study have been identified (Obj. 1) and needed equipment has been purchased. The next phase of field studies to evaluate the impacts of vegetative buffer strips (VBS) on reducing the transport of herbicides and veterinary antibiotics will be completed this year (Obj. 2a), with the inclusion of a tree-grass treatment that will be compared to the previously existing grass treatments. Several soil quality assessments, in association with the VBS study, have been conducted in the last year, including microbial enzyme activity, aggregate stability, carbon and nitrogen concentrations, DNA extractions, and an atrazine degradation study. Determination of the sorption intensity of atrazine and the antibiotic, sulfamethazine, are currently underway. Hydrologic equipment for measuring water quality and quantity from various grain and bioenergy management systems were fabricated and are being installed on 18 plots this year (Obj. 2b). Research related to improving the capability of hydrologic simulation models is also progressing (Obj 3). Sensitivity analyses were conducted on several fields including Field 1 in Centralia and fields at the Greenley Experimental Station. ARS and University scientists have defined and tested parameterizations of Soil Water Assessment Tool and Agricultural Policy/Environmental eXtender (APEX), including sensitivity and uncertainty analyses for various climatic conditions. APEX input files have been developed for the 18 plots that will be monitored for water quality. Flow data have been revised at GCEW Weir 1 and constituents loads recalculated. A major quality assurance effort has been underway to systematically review our water quality database for omissions, lost samples, or questionable data.