Location: Soil Drainage Research2010 Annual Report
1a. Objectives (from AD-416)
The overall project goal focuses on improving subsurface drainage water management systems (DWMS), particularly those employing controlled drainage practices, which will be used throughout the Midwest U.S., to provide both environmental and economic benefits. Accomplishing this goal requires an integrated research program that leads to enhanced controlled drainage operational strategies, improvement of DWMS design, development of flooding tolerant crop cultivars, and innovation in agricultural water treatment technologies. Specific objectives include: 1) Develop a knowledge base that will provide useful insight for improving controlled drainage operational strategies so as to maximize environmental and economic benefits. 2) Collect field data that will offer useful insight on proper DWMS design (particularly for controlled drainage systems), and then conduct a computer modeling investigation to determine the best controlled drainage design criteria and operational strategies that provide environmental and economic benefits. 3) Develop flooding stress tolerant soybean cultivars that are better adapted to Midwest U.S. DWMS wet soil conditions. 4) Develop constructed wetland and other water treatment technologies that can be integrated with DWMS to reduce nutrient and pesticide losses from cropland and turf environments.
1b. Approach (from AD-416)
Conduct plot studies to quantify the subsurface drainage effects of three outlet control structure weir elevations and a scenario in which the outlet control structure weir height is gradually lowered. Conduct producer operated, field scale comparisons between open, unrestricted versus controlled subsurface drainage systems. Determine the effects of controlled drainage versus open, unrestricted drainage on surface runoff. Determine the soil quality effects of controlled drainage verses open, unrestricted drainage. Perform laboratory tests and field investigations to quantify processes affecting nitrate mobility in low permeability Midwest U.S. soils that typically require artificial subsurface drainage. Conduct plot studies to evaluate different subsurface drainage system infrastructure characteristics for the purpose of improving DWMS design criteria. Using data collected from different Midwest U.S. field locations, calibrate and verify computer models capable of simulating DWMS flow, water quality, and crop yield responses. If necessary, modify the computer program used to develop the computer models. Screen soybean cultivars of diverse origins for flooding stress tolerance and employ quantitative trait locus (QTL) mapping on the most promising cultivars in order to locate genes on the genetic linkage map that are responsible for flooding stress tolerance. Develop transgenic soybeans with improved flooding tolerance and then verify their flooding tolerance. For three constructed wetlands, assess present water treatment effectiveness along with vegetation/wildlife function and then evaluate, on the same basis, improvement modifications. Perform laboratory tests to screen novel filter materials for ability to remove nitrate and atrazine from drainage water. If an effective and efficient filter material is isolated in the laboratory, a field pilot test will follow. Evaluate the ability of commercially available filter materials to absorb or bind nutrients and pesticides present in tile drainage water from an urban turf environment.
3. Progress Report
1a- Progress at the Defiance Agricultural Research Association (DARA) field research site is described in detail within the AD-421 for Project 3604-13000-008-14S. DARA site water quality, water flow, water level, and crop yield data continue being collected, stored on a computer database, and analyzed. Over the past year, two of the test plots were operated in controlled drainage mode, while conventional, unrestricted drainage practices were being used at the other two test plots. 1b- Drainage flow data, drainage water samples, and crop yields from free drainage and managed drainage treatments were obtained at 8 paired field sites on privately owned farms. 1c- Surface and subsurface flows were measured from 8 small research plots in response to controlled rainfall/irrigation when operated in both free drainage and drainage water management modes. 1d– Cone penetrometer surveys have been carried out at three additional sites in order to evaluate drainage water management impacts on soil compaction. 1e– Insufficient funds did not allow the installation of instrumented field test plots to study nitrate transport processes in soil. However, laboratory investigations continue with regard to quantifying nitrate transport processes in soil. 2a- Progress is the same as described in Subobjective 1a for the DARA field research site. 2b– A lack of operational funds did not allow a masters or doctoral student to be hired for the purpose of conducting computer hydrologic simulation research. 3a– Characterization of the recombinant inbred (RI) population S99-2281 x PI 408105A with over one thousand DNA markers was completed. Genetic loci associated with tolerance of field flooding and Phytophthora root rot disease have been identified. Testing of the RI population S99-2281 x PI 408105A for adventitious root development and root growth in response to flooding was completed. 3b– Thirty nine transgenic soybean lines containing the SAG12:IPT gene were field tested for yield and delaying senescence. Transgenic soybean plants containing the flood tolerant candidate genes MYB-XET, MYB-GLB1, and 35S-GLB1 are being tested for copy number of the inserted gene. 4a– Only one of three Wetland Reservoir Subirrigation System (WRSIS) sites remains operational. Field sampling of wildlife (fishes, amphibians, and reptiles) and physical habitat (water surface area, water depth, ratio of open water to emergent wetland vegetation) has been completed and a manuscript is in preparation. 4b– Laboratory hydraulic conductivity tests, contaminant removal batch tests, and saturated solute transport column experiments have documented the feasibility of using a new modified iron product as a filter material to remove nutrients (nitrate/phosphate) and pesticides (atrazine) from drainage waters. 4c- The laboratory portion of the research has been completed, with results indicating that the end-of-tile approach was viable if the capacity to treat greater flow rates could be addressed. Progress continues with respect to the field portion of the study. Additional filter materials are being tested at field sites in TX, MN, and OH.
1. Screening efforts have identified soybean genotypes differing in susceptibility to flooding. The flooding tolerant PI 408105A showed only 32.1% reduction in yield compared to 81.2% reduction in the flooding-sensitive S99-2281 genotype. A recombinant inbred (RI) population that segregates for flooding tolerance was developed from a cross of PI 408105A x S99-2281. To investigate the physiological trait associated with flooding tolerance, 200 RI lines were tested for their ability to develop adventitious roots from stem section near the soil surface, to give the plant more access to oxygen during times of flooding. The PI 408105A plants produced 32% more adventitious roots and had a 74% greater root biomass than the S99-2281 plants. Genetic loci associated with triggering early adventitious root formation and abundant root growth in response to flooding stress will be identified and used in the development of flooding-tolerant soybean cultivars.
2. Development of design and management criteria for fish, amphibian, and reptiles within created wetlands. The design and management of agricultural wetlands focuses on optimizing the ability of created wetlands to reduce nutrient, pesticide, and sediment loadings within agricultural runoff. This focus on water quality results in the creation of wetlands that may not function effectively as habitats for aquatic vertebrates that are exhibiting worldwide population declines, such as fishes, amphibians, and reptiles. ARS scientists in Columbus, Ohio documented differences in fishes, amphibians, and reptiles between two wetland types created as a result of the wetland-reservoir-subirrigation system (WRSIS) and used the information to develop design and management criteria capable of increasing the ecological benefits resulting from this agricultural water recycling system. Differences in amphibian abundance and species composition between WRSIS wetlands and reservoirs suggest the potential for WRSIS wetlands to provide habitat for a different suite of aquatic vertebrates than the reservoirs. Furthermore, WRSIS dominated by fishes did not exhibit the benefits of a two stage wetland design. These results enabled the development of a set of design and management criteria that will enable WRSIS wetlands to be managed as amphibian habitat and reservoirs to be managed as fish habitat. These design and management criteria can also be used by state, federal, and private agencies involved with creating agricultural wetlands to assist them meeting their conservation and restoration goals.
3. Laboratory feasibility testing of a newly developed modified iron product for possible use as a filter material to remove contaminants from drainage waters. Filter treatment systems can potentially remove nutrients and pesticides from water discharged by subsurface drainage systems in both large and small scale agricultural settings. The success of these treatment systems will depend on finding economic filter materials that are capable of effectively and efficiently removing nutrients and/or pesticides. Laboratory saturated hydraulic conductivity tests, contaminant removal batch tests, and saturated solute transport tests were conducted to assess the feasibility for using a new modified iron product as a filter material to treat nutrients and pesticides present in agricultural drainage waters. Saturated hydraulic conductivity tests indicate that the modified iron product has a sufficiently high permeability to allow substantial drainage water flow rates when used as a filter material. The contaminant removal batch tests and the saturated solute transport tests show that this modified iron product is capable of almost completely removing phosphate and the pesticide, atrazine, from drainage water, even when contaminant levels and flow rates are relatively high. The batch and column tests additionally indicate that this modified iron has the ability to remove moderate amounts of nitrate from drainage waters. Consequently, this modified iron may in the future prove valuable for reducing the adverse environmental impacts associated with agricultural subsurface drainage practices.
4. Determined the feasibility of an end-of-tile filter approach to reduce nutrient and pesticide transport via subsurface drainage. Subsurface drainage is a necessity for crop production agriculture in humid climates with poorly drained soils. In excess of 20.6 million ha (37%) of the tillable acres in the Midwest are managed with subsurface tile. While partially responsible for consistent high crop production yields, subsurface tile drainage has been recognized as a primary source of agricultural nutrient transport to streams and waterbodies to which they discharge. ARS scientists in cooperation with United States Golf Association (USGA) personnel investigated the feasibility of an end-of-tile filter for treating subsurface drainage waters. The findings suggest that the end-of-tile filter approach could be adapted as a best management practice to reduce nutrient and pesticide transport in subsurface tile drainage where the contributing area and flow rates are relatively small. Additionally, the findings support further investigation into alternative sorbent materials and delivery designs that permit larger drainage areas and greater flow rates to be filtered. The beneficiaries of this research are all downstream water users that use surface water for drinking, recreation, and navigation.Pham, T.A., Hill, C.B., Miles, M., Nguyen, B.T., Vu, T.T., Vuong, T.D., Vantoai, T.T., Nguyen, H.T., Hartman, G.L. 2010. Evaluation of Soybean Germplasm for Resistance to Soybean Rust in Vietnam. Field Crops Research. 117(2010):131-138.