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Research Project: Developing Agricultural Practices to Protect Water Quality and Conserve Water and Soil Resources in the Upper Midwest United States

Location: Soil and Water Management Research

2022 Annual Report

1. Develop irrigation and drainage strategies in the North Central United States to protect water and soil resources a. Determine the potential of amendments to mitigate leaching and contamination of groundwater from agricultural operations. b. Identify materials and designs that will maximize contaminant removal from subsurface drainage water. 2. Identify and test innovative management practices to reduce potential adverse impacts on water quality or conserve water resources. a. Evaluate the effectiveness of low-input turf and management practices to reduce contaminant transport with runoff. b. Identify and test management practices to reduce reactive nitrogen leakage from dairy farming systems. c. Determine the impact of perenniallizing practices on the nutrient and water balances of corn/soybean systems. d. Determine the influence of management practices and water conservation strategies on water use and the occurrence and fate of contaminants in urban agriculture. 3. Conduct research as part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the U.S., use the Upper Mississippi River Basin LTAR site to improve the observational capabilities and data accessibility of the LTAR network and support research to sustain or enhance agricultural production and environmental quality in agroecosystems characteristic of the Upper Mississippi River Basin. Research and data collection are planned and implemented based on the LTAR site application and in accordance with the responsibilities outlined in the LTAR Shared Research Strategy, a living document that serves as a roadmap for LTAR implementation. Participation in the LTAR network and test innovative management practices to reduce potential adverse impacts on water quality or conserve water resources includes research and data management in support of the ARS GRACEnet and DAWG projects.

Protecting the integrity and supply of our water resources is one of the most important issues we will face this century and therefore the foundation of our project’s objectives (objectives 1 and 2). Our research approach requires laboratory to field scale investigations focusing on two strategies, prevention and mitigation. With the prevention strategy we will identify and understand the fate of potential water contaminants (e.g. agrochemicals: fertilizer, pesticides; anthropogenic compounds) and develop practices to prevent or minimize the off-site transport of contaminants from their site of application or point of origin. For instance, we will evaluate the fate of biochar and its efficacy as a soil amendment to reduce the leaching of agrochemicals (subobjective 1a), management practices to minimize agrochemical transport with storm runoff from low-input turf (subobjective 2a.1), and the occurrence of contaminants in urban agricultural systems and the influence of water conservation and management practices on contaminant availability (subobjective 2d). In addition, we will determine the influence of perennial cover crops and the use of different irrigation and nitrogen rates to reduce transport of nutrients with runoff and drainage from row crops subobjective 2c). Model simulations will also be used to predict nitrate loads in tile drainage from a concentrated animal feeding operations (CAFO) dairy and simulate the efficacy of alternative practices to reduce loads (subobjective 2b). In circumstances where contaminants are transported off-site with overland flow or leaching, mitigation strategies will be taken to remove contaminants from runoff and tile drainage before they reach surface waters or groundwater. Mitigation approaches include plot-scale studies to identify optimal buffer size and management of low-input turf for the removal of contaminants transported with runoff (subobjective 2a.2), while field and modeling experiments will identify the most effective bioreactor design and materials for removing nutrients from subsurface drainage water (subobjective 1b). Laboratory, field, and small watershed studies will be employed to enhance and extend the research that has been initiated to develop aspirational farming practices (ASP) for the Upper Mississippi River Basin and to compare their environmental and economic metrics against business as usual (BAU) farming practices in the region. Management practices that will be explored include maintenance of continuous living cover in sensitive locations on the landscape, and downstream or down-gradient practices that remove excess nutrients and reduce N2O emissions. Our multidisciplinary team and the interrelationship of our project subobjectives within and across these strategies will make progress towards the national goal for improved water resource security.

Progress Report
Analyses were completed on biochar samples that were returned from the volunteers who participated in the citizen science effort of aging biochar in their respective soils. We observed an alteration in greenhouse gas production potentials and increases in the water extractable metal species following soil exposure, particularly iron. Due the significant accumulation of iron in the aged biochar samples, we designed an additional experiment to evaluate the potential impact of dissolved iron species interacting with the biochar. We observed that the exposure of the biochar to iron solutions under laboratory conditions (with no external heating or additional water pressure applied) increased the sorption capacity of the biochar nearly 2-times, as well as increased the water-holding capacity nearly 3-times. These biochar-dissolved species interactions also provided additional physical protection against fragmentation. This research has demonstrated that the rate-limiting step for moisture interaction with biochar is driven by the phase change (first order process) and not a diffusional limitation. It was also observed during the analysis of the aged biochar samples that selection of analytical instrumentation and software signal deconvolution algorithms has profound impacts on the results for interpreting carbon electron bond configurations in aged biochar samples. Initial research data on the sorption of bicyclopyrone to a variety of soils was published, with the most striking result being the lack of correlation between soil organic matter and the soil’s sorption capacity for bicyclopyrone. For the first time, the fate of the allelochemical coumarin in unamended and soil amended with fresh and soil-aged biochar was determined. Biochar additions modified the soil’s retention capacity towards coumarin and consequently changed its degradation and leaching patterns. The aging process did not alter the sorption capacity of biochar with respect to coumarin, likely, the increase in organic matter content was the dominant factor that controlled sorption of the compound instead of the surface chemistry alterations due to soil aging. There was no consistency between dissipation, leaching and application rate, which reveals the problems relating dissipation and mobility of natural compounds in soils, since they are rapidly degraded. Biochar additions enhanced coumarin’s activity only at high application rates. These results supply guidance for the use of biochar amendments as a promising tool for enhancing the activity of allelochemicals. Dosing woodchips in a denitrification bioreactor with a readily available carbon source doubled nitrate removal rate from tile drainage water without increasing nitrous oxide concentrations. Research in this process showed that a three-bed bioreactor can treat tile drainage from a one-square-mile watershed, and that sedimentation can negatively impact performance. A control system designed and installed to monitor influent turbidity and close off flow during periods of high-sediment flux prevented further problems. Continuous nitrate-nitrogen sensors have been deployed and provided real-time confirmation of conservation practice effectiveness. Monitoring of a watershed adjacent to the bioreactor watershed supported preparation for a paired watershed experiment. Relationships with local producers and conservation professionals enlisted their cooperation in the paired watershed efforts. Experiments were designed to evaluate the effectiveness of low-input turf and management practices of turfgrass filter strips to mitigate contaminant transport with runoff. Replicated plots were planted with a fine fescue mixture and managed at different heights of cut. The base of each plot contained a runoff collection gutter, flume, flow meter and automated sampler to record runoff volumes and flow rates and to collect samples throughout rainfall events. A rainfall simulator provided precipitation at desired rates and durations. A manifold system delivered runoff containing sediment, nutrients from fertilizer, herbicides, fungicides, insecticides, and a conservative tracer to the top of the filter strip. Each manifold system included a mixing tank with trolling motor, pump and flow meter. Manifold samples entering the filter strip and runoff samples leaving the filter strip were collected throughout the simulated storm event and compared for contaminant content. Water samples were analyzed for specific contaminants according to published procedures or methods developed in our laboratory. Replicated evaluations across multiple years provided hundreds of samples. Analysis of inorganic compounds of interest have been completed. Chemical analysis of organic contaminants of interests are complete or nearing completion. Data analysis of contaminant loads entering and exiting the filter strips identified management practices that were most effective towards contaminant removal. Delivering the manure with center pivot irrigation during the growing season rather than with fall injection reduced tile drainage nitrate losses in a manured silage corn-alfalfa dairy cropping system. In-season application allowed reduction in rate without loss of productivity. Published research showed that alfalfa, relative to corn silage, reduced losses of nitrate-nitrogen and sediment in tile drainage. An environmental assessment of U.S. dairy farms, which included our input on crop, feed, management practices, and water impacts in the Upper Midwest, indicated the loss of reactive nitrogen is a significant industry challenge, with water-borne losses critical in our region. Field phosphorus (P) budgets from this research, via inclusion in a national P budget database, provided context for understanding cropping systems’ contributions to phosphorus-related water quality problems. We conducted intensive soil sampling of our Long-Term Agroecosystem Research (LTAR) “aspirational” and “business as usual” fields with cores to 75 cm depth at 64 locations in each field. These will be compared to samples taken at the start of the experiment to document changes due to differences in management. In related work, an experiment was conducted in the aspirational system to determine the spatial distribution of corn and clover roots, and to determine the fate of nitrogen released by decomposing clover. We found virtually no corn roots in the interrow region, indicating that very little of the clover-derived N was taken up by the corn. We also found higher N2O emission from the interrow than from the row. In the Water Parcel Tracking project, we mapped in-stream nitrate concentrations in the High Island Creek watershed on multiple occasions, using our inflatable raft-based platform. Overlaying the nitrate maps with maps of land use and funded conservation practices is now being conducted to estimate the effectiveness of those practices. Community gardens were visited for observation of management practices, and samples were collected in the Twin Cities metropolitan area. This provided insight on practices and inputs associated with urban agriculture. Replicated plots were established to provide scientific assessments of contaminant transport with leachate, crop growth, harvest yields, and cost of urban food production in conventional, alternative, and innovative urban agricultural systems. Raised bed plots were constructed on stainless steel trays that guided water leaching from the plant matrix to flumes for sample collection. Selected crops included vegetables that represent harvest of fruits, roots, and leafy greens. Moisture content and temperature of planting matrix (soil, straw bale, or layered no-dig) was periodically measured before and after natural or simulated precipitation. Subsamples of raised bed inputs and end-of-season planting matrix were analyzed and compared. Concentrations of nitrogen and phosphorus were measured in water samples leached from each raised bed to assess off-site transport of excess nutrients. Measure of leaf chlorophyll, plant nitrogen content, and harvest yields were also compared between identical crops grown in the three urban agricultural systems. These studies showed the influence of management practices on the productivity, cost, and environmental contaminant transport from the urban agricultural systems evaluated. Research was conducted as part of the LTAR network, representing the Upper Mississippi River Basin site. Collection of grab surface water samples and deployment of polar organic chemical integrative samplers were conducted for multiple years as part of a cooperative effort with other LTAR locations, led by the Lower Chesapeake Bay site. Sample collection and analyses are nearly complete. Data evaluation is ongoing. The project goal is to track the transport and fate of nitrogen in agricultural watersheds. Additional LTAR related research involved development of new methods to map nitrate concentrations in watersheds and related spatial differences to edge-of-field conservation practices, use of a stable isotope mass spectrometer for improved tracing of carbon cycling and mechanistic level nitrogen cycling, and “aspirational” and “business as usual” research (see 2c). Scientists from St. Paul, Minnesota, are active participants in LTAR working groups including Croplands, Drainage, Eddy Covariance, Non-CO2 Greenhouse Gases, Resilience, Soil, Water Quality, and Water Quantity. This is the final report for this project which terminated on May 21, 2022 and is replaced by project, 5062-12130-008-00D, “Developing and Evaluating Strategies to Protect and conserve Water and Environmental Resources While Maintaining Productivity in Agronomic Systems” that was certified by OSQR on May 10, 2022.

1. Iron and biochar interactions increases chemical sorption capacity of biochar. There is a growing issue of antibiotic chemicals being detected in the environment. ARS researchers in St. Paul, Minnesota examined the potential use of biochar to reduce the presence and availability of antibiotics in agricultural soils, as well as simple pretreatment of the biochar with iron salt solutions to increase biochar’s removal effectiveness. They observed that modifying the biochar with an iron-salt solution increases the observed antibiotic sorption capacity of the biochar nearly 2-times. Additionally, adding the iron-treated biochar to the soil system at 2% (w/w) did increase the half-life (the time for 50% of the antibiotic to be removed from the water) from 4 to 6.4 days. These results will assist scientists and engineers, supplying guidance for the influence of biochar additions in mitigating antibiotics and other agrochemicals in the soil system.

2. Fine fescue vegetative filter strips mitigate herbicide transport in runoff. Herbicides are a useful tool for controlling weeds in crops and on managed landscapes. However, they may be transported from their site of application with runoff to locations that may impact sensitive non-target organisms. ARS researchers at St. Paul, Minnesota, conducted studies to evaluate the ability of a fine fescue mixture vegetative filter strip to reduce quantities of herbicides transported with surface runoff. Measurement of herbicides (dicamba, mecoprop-p and 2,4-D) in runoff entering and exiting a 50-ft vegetative filter strip revealed the fine fescue turfgrass mixture removed 67 to 99% of the herbicides that were transported with runoff. This research data is important to land managers to help support decisions toward enhanced environmental stewardship and to scientists for modeling larger scale impacts of implementing these mitigation measures.

3. A living mulch system enhances soil infiltration and reduces soil erosion in row crops. Corn and soybean farmers are encouraged to use winter cover crops for a variety of reasons, but it is challenging and expensive to replant them every fall. Perennial living mulches have been proposed as way to get the benefits of cover crops while only having to plant them once. ARS researchers at St. Paul, Minnesota, completed a 5-year project examining the long-term environmental impact of a new farming practice – growing corn and soybeans in a perennial living mulch of kura clover. This research was conducted at Rosemount Minnesota and Arlington Wisconsin. After 5 years of planting row crops in both treatments, all of the soil property measurements were repeated. While no differences were found in many soil properties, there were large differences in water infiltration rates – which were 10-19 times higher in the living mulch system compared to the conventional system. In a related experiment, storm runoff was measured on sloped plots with both systems, and the living mulch system reduced erosive soil loss by 93% compared to the conventional system. These results show that growing corn in a perennial living mulch is a promising management practice for producers challenged by either poor water infiltration or soil erosion.

4. Alfalfa reduces nitrate and phosphorus loads in tile drainage water from manured fields. Dairy products provide needed protein at a reasonable price, yet manure management practices on large, concentrated dairies can negatively impact natural water system health. ARS researchers in St. Paul and Morris, Minnesota, monitored flow rate, and nitrate, phosphorus, and sediment concentrations in tile drainage water from manured silage corn and alfalfa fields on a modern dairy. Alfalfa substantially reduced weekly nitrate and phosphorus loads and annual sediment loads compared to silage corn. These results indicate that surface and groundwater quality may be improved by increasing alfalfa acreage with respect to silage corn in dairy production systems. This research underscores the importance of perennials such as alfalfa for dairy producers to protect water resources.

Review Publications
Spokas, K.A., Bogner, J., Corcoran, M. 2021. Modeling landfill CH4 emissions: CALMIM international field validation, using CALMIM to simulate management strategies, current and future climate scenarios. Elementa: Science of the Anthropocene. 9(1). Article 00050.
Gamble, J.D., Baker, J.M., Dalzell, B.J., Wente, C.D., Feyereisen, G.W. 2022. Ecohydrology of irrigated silage maize and alfalfa production systems in the Upper Midwest US. Agricultural Water Management. 267. Article 107612.
Ferrari, F., Thomazini, A., Pereira, A., Spokas, K.A., Schaefer, C. 2022. Potential greenhouse gases emissions by different plant communities in maritime Antarctica. Annals of the Brazilian Academy of Science. 94(4).
Feyereisen, G.W., Hay, C.H., Christianson, R.D., Helmers, M.J. 2022. Eating the metaphorical elephant: Meeting nitrogen reduction goals in Upper Mississippi River Basin states. Journal of the ASABE. 65(3):621-631.
Goebel, K.M., Davros, N.M., Andersen, D.E., Rice, P.J. 2022. Tallgrass prairie wildlife exposure to spray drift from commonly used soybean insecticides in Midwestern USA. Science of the Total Environment. 818. Article 151745.
Lentz, R.D., Ippolito, J.A., Spokas, K.A. 2022. Does turbulent-flow conditioning of irrigation water influence soil chemical processes: II. Long-term soil and crop study. Communications in Soil Science and Plant Analysis. 53(5):636-650.
Williams, M.R., Welikhe, P., Bos, J.H., King, K.W., Akland, M., Augustine, D.J., Baffaut, C., Beck, G., Bierer, A.M., Bosch, D.D., Boughton, E., Brandani, C., Brooks, E., Buda, A.R., Cavigelli, M.A., Faulkner, J., Feyereisen, G.W., Fortuna, A., Gamble, J.D., Hanrahan, B.R., Hussain, M., Kohmann, M., Kovar, J.L., Lee, B., Leytem, A.B., Liebig, M.A., Line, D., Macrae, M., Moorman, T.B., Moriasi, D.N., Nelson, N., Ortega-Pieck, A., Osmond, D., Pisani, O., Ragosta, J., Reba, M.L., Saha, A., Sanchez, J., Silveira, M., Smith, D.R., Spiegal, S.A., Swain, H., Unrine, J., Webb, P., White, K.E., Wilson, H., Witthaus, L.M. 2022. P-FLUX: A phosphorus budget dataset spanning diverse agricultural production systems in the United States and Canada. Journal of Environmental Quality. 51:451–461.
Baker, J.M., Feyereisen, G.W., Albrecht, K.A., Gamble, J.D. 2022. A perennial living mulch substantially increases infiltration in row crop systems. Journal of Soil and Water Conservation. 77(2):212-220.
Ducey, T.F., Sigua, G.C., Novak, J.M., Ippolito, J.A., Spokas, K.A., Johnson, M.G. 2021. Microbial response to phytostabilization in mining impacted soils using maize in conjunction with biochar and compost. Microorganisms. 9(12), Article 2545.