Objective 1: Develop strategies to mitigate landscape scale attributes for improved soil and water quality and production efficiency. Sub-objective 1.1 Explore surface and subsurface hydrologic processes affecting soil quality and vulnerability on tile-drained landscape. Sub-objective 1.2 Evaluate sources and flow pathways of water and nutrients in tile-drained landscapes. Objective 2: Improve nutrient management efficiency to minimize water quality degradation and maximize agricultural production. Sub-objective 2.1 Assess the influence of combined conservation practices on soil organic matter transformations, nutrient cycling, and crop yield. Sub-objective 2.2 Evaluate soil P drawdown rates, plant phosphorus uptake, and potential changes in corn and soybean yield with elimination of phosphorus fertilizer to long-term fertility research plots. Sub-objective 2.3 Determine the critical phosphorus concentration for corn and soybean cultivars common to the Midwest using the Genetics X Environment X Management (GxExM) approach. Sub-objective 2.4 Evaluate quantity/intensity relationships and the kinetics of phosphorus release in diverse soils in working towards the long-term goal of improving soil fertility recommendations. Objective 3: Develop and refine decision support tools. Sub-objective 3.1 Develop software and database architectures to support collecting and managing observed natural resource data. Sub-objective 3.2 Develop decision support tools to explore and integrate observed field and small watershed data with spatial models. Sub-objective 3.3 Test and improve tools for assessment of climate change impacts on model predictions of soil erosion and chemical losses. Objective 4: Operate and maintain the Eastern Corn Belt LTAR network site in partnership with the Soil Drainage Research Unit, Columbus, OH and the National Center for Water Quality Research, Heidelberg University, Tiffin, OH using technologies and practices agreed upon by the LTAR leadership. Contribute to the LTAR working groups and common experiments as resources allow. Submit relevant data with appropriate metadata to the LTAR Information Ecosystem. Sub-objective 4.1 Develop water, nitrogen, and phosphorus budgets for agricultural fields under prevailing management practices in the Eastern Corn Belt. Subobjective 4.2. Evaluate relationships between soil and water quality, and greenhouse gas emissions under different cropping and management scenarios in the Eastern Corn Belt.
Objective 1: Both laboratory and field studies will be used to gain a better understanding of the hydrologic processes that control erosion at various locations in the landscape and assess sources and flow pathways of nutrients and water to streams. This will involve assessing the effect of subsurface tile drains on in-stream variability of nutrient concentration and isotopic signatures. Indoor rainfall simulation tools and a stream survey will be utilized to accomplish the listed objective. Objective 2: Regarding soil quality and phosphorus fertilizer recommendations, laboratory and field experiments will be used. Current long-term field experiments where various crop rotations and best management practices have been implemented will provide soils for detailed laboratory analysis to assess the impact of the given practices on soil quality. For phosphorus fertilizer recommendations, the approach is to construct a controlled indoor growth facility and evaluate phosphorus uptake by various crop cultivars, followed by a detailed experiment on quantifying the ability of soil to supply dissolved phosphorus to solutions using long term incubations and various types of extraction methods. Objective 3: Computer programs will be developed for automation of uploading environmental data into the proper format for use by several models, as well as convert to specified data formats, and help interpret validation data from model simulations. This includes incorporation of various future climate scenarios into different models. Objective 4: Discharge, water quality data, and producer surveys will be used to develop water and nutrient budgets for agricultural fields in the Eastern Corn Belt region. This research will link soil quality parameters and soil processes to water quality and gas flux data collected from monitored field sites.
Experiments on effects of subsurface hydrology on soil erodibility have been conducted and results have been analyzed. Initial experiments on nutrient loss under vertical hydraulic gradients, i.e., drainage and seepage conditions, were conducted under simulated rainfall. Experiments have been designed to quantify lateral subsurface flow effects on nutrient transport. Three longitudinal stream surveys have been completed to date under baseflow stream conditions. During each sampling campaign, water samples were collected every 100 m along the entire ditch network and all tile drains flowing into the ditch. Additional outside funding from NRCS allowed us to expand the study stream length from 3.5 to nearly 9 km. It also provided funds to collect sediment samples from the ditch every 100 m over the entire length. A fourth stream survey is planned for August 2020. All edge-of-field data from sites in Ohio and Indiana have been organized and summarized into nutrient budgets. A paper was accepted for publication from this work. As a follow-up project on nutrient budgets, this project is currently being expanded via Long-Term Agroecological Research (LTAR) funding to other locations. In August 2019, we hired a post doc to complete phosphorus budgets for all 18 LTAR locations and have also engaged collaborators outside of ARS to be included in the project. Using our newly constructed indoor growth room, we completed the first experiment on determining phosphorus (P) requirements for three corn cultivars. This growth room utilized sand-culture hydroponics and the ability to control environmental conditions. Specifically, through the use of inert sand (i.e. quartz-based) we could precisely control the nutrient concentrations in which the plants were exposed with a nutrient injection system built into the drip irrigation. We successfully grew corn to full maturity with 100% artificial conditions, producing corn plants that were identical to what is observed in the field. From this study, we determined that the minimum P uptake for achieving maximum corn grain yield varied between cultivar but was in the range of 550 to 630 mg P per plant. Maximum biomass production was measured at 800 mg P uptake. Beyond these threshold levels of P uptake, the plant continued to uptake P, but with no further increases in grain yield or biomass. Thus, luxury consumption of P for corn, which has never been documented to our knowledge. The next experiment will examine P uptake timing, and, also minimum P requirements for soybeans. A new command-line tool called Water Erosion Prediction Project (WEPP) Climate File Formatter (WEPPCLIFF) was developed by Purdue University cooperators and an ARS scientist at West Lafayette, Indiana, that can prepare climate inputs for soil loss models (e.g. WEPP, Revised Universal Soil Loss Equation 2 (RUSLE2) from observed or predicted time series data. WEPPCLIFF was implemented in parallel so that both large networks of station data or gridded inputs could be processed in a reasonable time. The software performs many common and advanced functions when specified including storm separation (a function uniquely critical for erosion modeling), quality checking, gap filling, data visualization, and data export The software should be an important contribution to erosion science and modeling efforts with WEPP and many other models whose formatting outputs are adopted by WEPPCLIFF in the future. To evaluate the potential runoff and soil loss differences among various climate data sources including climate generator (CLIGEN) stations, observed 15-min, probabilistic model checker (PRISM) and General Circulation Models (GCM) datasets, we selected 20 locations representing different climatic conditions across the US. These locations include Northeast, Southeast, Midwest, Great Plains North, Great Plains South, Northwest, and Southwest regions of the US. A python script has been developed that replaces monthly values of precipitation, temperatures, and wet/dry days from PRISM and GCM with those in the CLIGEN database to evaluate CLIGEN equivalent PRISM and GCM database predictions of runoff and soil loss from WEPP. Climate inputs to WEPP were generated for the 20 locations utilizing the MarkSim tool, as well as a new tool called WEPPcloud provided by the University of Idaho. These will be utilized in further WEPP model simulations, and comparisons of results. The WEPPcloud watershed interface is a comprehensive online geospatial modeling tool developed collaboratively over the last ten years by the University of Idaho, the USDA Forest Service Rocky Mountain Research Station, and an ARS scientist at West Lafayette, Indiana. This watershed interface tool accesses and integrates publicly available geospatial and time-series data including topographic, soils, and land use maps and associated databases as well as climate and streamflow data, and automatically delineates hillslopes, stream channels, and watersheds from a user defined outlet point, which is then used to drive WEPP. WEPPcloud allows users to run scenarios using grid-based current climates (PRISM-adjusted) historic weather datasets (DAYMET, GRIDMET) but also downscaled future climate projections through 2100. The GRIDMET data uses a set of 20 CMIP5 GCMs from models that provides daily output for historical (1950-2005) and future climate under RCP4.5 and RCP8.5 downscaled at 4-km grid. WEPPcloud automates the acquisition of data sources for running WEPP hydrologic simulations. The online interface allows non-GIS/non-hydrologists to quickly obtain and apply the best available data sources and physically-based modelling to areas of interest. The latest available products in climate modeling include those from the Coupled Model Intercomparison Project 6 (CMIP6). This latest iteration in the CMIP eras provides GCM outputs that are higher resolution (temporally and spatially) and more capable than any preceding era. While many modelers are still conducting experiments with coarser CMIP5 outputs, several model outputs have already been acquired at West Lafayette, Indiana, from CMIP6 and new modeling efforts are being designed with those new outputs as a top priority. Since these outputs are being provided at much higher resolution, better downscaling tools can be developed, uncertainty from downscaling can be reduced (due to less scaling needed), and some outputs may not need downscaling at all, which is being investigated as well. Sensor data from ARS field sites continues to be uploaded to a central website where users can view the latest weather and soil moisture data. Work has also continued in using the Aquarius database system to catalog and quality check all data for the ARS field research sites in Northeast Indiana. Ongoing field instrumentation updates have been supported through database configuration changes on the server and data access protocol changes on the data loggers and cell modems. A decision support tool for the design of phosphorus removal structures was completed and is currently being tested by cooperators. This software allows a user to design different types of phosphorus removal structures based on site conditions, phosphorus absorbing material characteristics and structure parameters. The P-TRAP software allows users to explore different designs to meet performance goals for P removal amounts and material lifetime. A database of P absorbing material characteristics is included based on previous laboratory experiments.
1. Amending soil with biochar may enhance erosion. There is an increasing interest in using biochar to improve soil fertility and nutrient retention. However, the effects of biochar addition on soil erosion remain unclear. ARS researchers at West Lafayette, Indiana, and Chinese cooperators conducted a rainfall simulation study by mixing different amounts of biochar with the soil (0 to 8% by weight) and incubated for 140 days. Results showed that the amount of runoff from biochar amended soil decreased slightly (2 to 10%), but the soil loss was increased significantly (20 to 50%), as compared to the control treatment. The benefit of an increased infiltration or water conservation from biochar addition is overshadowed by the increased erosion. Our results implied that biochar addition to soil could increase the risk of erosion on sloping croplands, therefore, one should exercise caution when amending soil with biochar on areas with potential for soil erosion.
2. Corn can experience luxury consumption of phosphorus. Developing more precise corn phosphorus recommendations will improve agronomic and economic efficiency, as well as prevent water quality degradation and conserve geologic phosphorus reserves. In the first step of this multi-faceted research, ARS researchers at West Lafayette, Indiana, developed a state-of-the-art indoor growth chamber utilizing sand-culture hydroponics for precise control of solution nutrient concentrations, followed by growing several corn varieties under a range of phosphorus concentrations applied with irrigation water. Results showed that corn requires uptake of 550 to 630 mg phosphorus in order to achieve maximum grain yield, and 800 mg for maximum biomass yield, under optimum conditions. However, corn will continue to uptake phosphorus beyond these levels with no further yield increases, resulting in “luxury consumption”. Luxury consumption is known for nitrogen and potassium but has never been documented for phosphorus. This information is critical to revising corn phosphorus recommendations.
3. WEPPCLIFF: a new tool to prepare climate files. In order to estimate soil loss using models such as the Revised Universal Soil Loss Equation version 2 (RUSLE2) and the Water Erosion Prediction Project (WEPP), climate inputs need to be formulated specifically for these models. With the availability of weather data from a large network of stations, a tool is needed to process these weather data in the specific format that can be used directly for erosion estimates. Scientists at West Lafayette, Indiana, and Purdue University cooperators developed WEPP Climate File Formatter (WEPPCLIFF) to prepare climate inputs for the WEPP and RUSLE2 models. The software performs many common and advanced functions when specified including storm separation, quality checking, gap filling, data visualization, and data export. WEPPCLIFF is an open-source software, which means that it allows others to make modifications and improvements. By facilitating the processing of weather data, WEPPCLIFF allows erosion estimates to be made with the most current information, instead of outdated climate data that may not reflect the changing climate.
McGehee, R.P., Flanagan, D.C., Srivastava, P. 2020. WEPPCLIFF: A command-line tool to process climate inputs for soil loss models. Journal of Open Source Software. 5(49):2029. https://doi.org/10.21105/joss.02029.
Gonzalez, J.M., Boddu, V.M., Jackson, M.A., Moser, B.R., Ray, P. 2020. Pyrolysis of creosote-treated railroad ties to recover creosote and produce biochar. Journal of Analytical and Applied Pyrolysis. 149. Article 104826. https://doi.org/10.1016/j.jaap.2020.104826.
Penn, C.J., Gonzalez, J.M., Williams, M.R., Smith, D.R., Livingston, S.J. 2019. The past, present, and future of blind inlets as a surface water best management practice. Critical Reviews in Environmental Science Technology. 50(7):743-768. https://doi.org/10.1080/10643389.2019.1642836.