Project : USDA ARS

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Research Project: Practices and Technologies for Sustainable Production in Midwestern Tile Drained Agroecosystems

2023 Annual Report

Objectives
Objective 1: Elucidate field and instream governing processes that control water quality and ecological response. Goal 1.1: Develop water table, soil moisture, and evapotranspiration measurement capacity within a subset of EOF network sites to better understand the water balance in tile drained landscapes. Hypothesis 1.2: The majority of observed edge-of-field P losses are attributable to old soil P rather than recently applied P fertilizers. Hypothesis 1.3: Preferential flow to subsurface tile drains are dominated by contributions from a relatively narrow band of the soil surface extending less than 1 m on either side of the drain. Objective 2: Quantify the response of ecosystem services (e.g., water quality, habitat, and biodiversity) to conservation practice implementation. Hypothesis 2.1: Implementation of conservation/aspirational practices (ASP) will significantly reduce edge-of-field surface and subsurface nutrient loss compared to business as usual (BAU) practices. Hypothesis 2.2: Including two or more conservation practices (stacking) will provide greater nutrient loss reductions compared to single practice implementation. Hypothesis 2.3: Improvements in soil health indicators will be associated with reduced edge-of-field nutrient losses. Hypothesis 2.4: Installation of instream inserts within an agricultural headwater stream will create riffle pool sequences that will increase instream habitat diversity and improve fish community integrity at the microhabitat spatial scale. Hypothesis 2.5: Installation of instream inserts in conjunction with channel rerouting and wetland creation will increase instream habitat diversity, improve fish community integrity, increase dissolved oxygen concentrations, and reduce downstream transport of nutrients. Hypothesis 2.6: Channelized agricultural headwater streams with greater instream habitat diversity will exhibit less nutrient concentrations and less within-season variability in nutrient concentrations and greater fish biodiversity and abundance. Objective 3: Contribute to LTAR network science, data synthesis, and model development through data collection and development/assessment of predictive tools. Hypothesis 3.1: Aspirational management systems (ASP) will improve soil health indicators compared to business-as-usual (BAU), but the degree of improvement will depend on site-specific factors. Goal 3.2: Identify the best environmental predictors of fish community structure in agricultural headwater streams in the Eastern Corn Belt LTAR node. Goal 3.3: Collect and synthesize data for Ohio high priority, agricultural tile drained watersheds.

Approach
Improved drainage, including subsurface tile and channelized streams, is required for sustainable agricultural crop production on an estimated 200 million ha of cropland worldwide. Another 425 million ha could benefit from improved drainage. The Midwest U.S. produces roughly 65% of the Nation’s annual corn and soybean production, largely as a result of artificial drainage. However, improved drainage has been linked to downstream water quality issues that include harmful algal blooms (e.g., Lake Erie and Gulf of Mexico) and hypoxia (e.g., Gulf of Mexico). Future climate predictions for the Midwest U.S. indicate more intense fall and spring storms and increasing temperatures that will heighten the importance of efficient drainage systems that maintain or improve ecosystem function and are in balance with new and/or enhanced production management practices, referred to as conservation/aspirational practices. Voluntary, incentive, and regulatory efforts have been applied to address agricultural nutrient loss and ecosystem function; yet, the problems persist. A combination of plot, field, and stream-scale research will be used to: isolate and understand the governing processes that control hydrological, water quality, and ecological responses; assess existing and novel management and conservation practices for their ability to reduce nutrient loss, enhance stream habitat and increase aquatic biodiversity; and synthesize the findings into improved simulation algorithms/scenarios for existing models and/or the development of new predictive tools. Successful completion of the proposed research will provide producers; certified crop advisors; extension specialists; researchers; drainage industry; conservationists; local, state, and federal action agencies; Western Lake Erie Basin (WLEB) and other watershed stakeholders; and decision/policy makers a better understanding of the governing controls and processes of nutrient dynamics in tile drained landscapes; quantitative assessments to develop and inform design, selection, and implementation of conservation practices; and enhance or improve the development and testing of prediction technologies.

Progress Report
In support of Objective 1: Goal 1.1. Soil moisture and temperature sensors as well as mobile flux towers and level loggers for groundwater stage measurement were secured. Soil moisture and temperature sensors as well as groundwater wells have been installed at select edge-of-field locations and data collecting is underway. Protocols for quality assurance and quality control (QA/QC) of the moisture and temperature data are continuing to be developed. Flux towers have been tested and installation following field treatment is planned. Hypothesis 1.2. The effect of recent phosphorus fertilizer applications on edge-of-field water phosphorus losses continues to be analyzed using an advanced statistical approach (weighted regression on discharge, and season). The analysis quantifies the relative contributions of recently applied P fertilizer and legacy soil phosphorus to phosphorus export at the edge-of-field and will translate findings into predictive models for characterization of phosphorus export at the field scale. A manuscript was published in Journal of Environmental Quality, and a second manuscript is under preparation. Hypothesis 1.3. Experimental plan for the utilization of bromide as a tracer of macropore flow is under development using a thorough review of the literature. Necessary supplies are in the process of being procured and modifications to the plots to facilitate measurement where the study will be conducted in ongoing. In support of Objective 2: Hypothesis 2.1. Significant progress continues to be made on assessing the water quality benefits of aspirational and business as usual practices. Field scale experiments are underway to explore the impacts of random vs systematic tile drainage, fertilizer placement, source and rate, conservation tillage, drainage water management and the use of cover crops. Supplemental plot scale experiments on fertilizer placement will end at the end of this water year. Additionally, on many of the fields, soil samples have and will continue to be collected to evaluate the effects of the various practices on soil health/quality. Hypothesis 2.2. Experiments to investigate the stacking or combination of practices are ongoing. Specifically, investigating the impacts of an upland practice with phosphorus removal structures, the combined effect of in-field practices combined with a two-stage ditch, and the combination of two in-field practices (reduced tillage and cover crops) are all ongoing. Hypothesis 2.3. Soil health measurements were completed from samples collected in 2020 and 2021. Analysis of the resulting data is on-going. One manuscript was published in Journal of Environmental Quality. Hypothesis 2.4. Fishes and instream habitat were sampled in the fall 2022 and spring of 2023. Initial analysis of the 2022 data were analyzed and presented to stakeholders at the annual meeting of the Midwest-Great Lakes Chapter of the Society for Ecological Restoration. Hypothesis 2.5. Weekly grab samples of nutrients have been collected on an ongoing basis since October 2022. Instream habitat and fishes were collected in the fall of 2022 and spring of 2023. Initial analysis of dissolved oxygen concentrations as part of assessing stream metabolism were completed and presented to stakeholders at the Ohio State University School of Environment and Natural Resources Undergraduate Student Symposium. Hypothesis 2.6. Field protocols for measurement of instream habitat diversity have been developed and refined. We are currently working with stakeholders to get permission to access identified sites on private lands for reconnaissance sampling of instream habitat diversity. In support of Objective 3: Hypothesis 3.1. A soil data inventory tool was published within the Long-Term Agroecosystem Research (LTAR) network. This tool provides information about all soils measurements taken across the 18 locations, in an easily accessible format, to all LTAR researchers. Goal 3.2. Initiated compilation of historical and current land use data from all ecology sites in St. Joseph River watershed (SJR) and Upper Big Walnut Creek watershed (UBWC). We have also begun compilations of the amounts of selected conservation practices (i.e., no-till tillage, cover crops, and Conservation Reserve Program (CRP) from within the watersheds of the ecology sites in SJR and UBWC. Additionally, continued making progress in the QA/QC checks of the SJR and UBWC ecology data. Goal 3.3. Plot, field and stream scale hydrology, water quality, soils, and ecology data continues to be collected to support site specific and cross location network research. Phosphorus budget data within the Eastern Corn Belt has been contributed to the LTAR water quality working and published within a network assessment and characterization related to phosphorus. Progress continues on four different cross location projects initiated and led by the drainage working group of the LTAR network. One year of high frequency discharge and precipitation data has been collected to support the assessment of dominant flow pathways. Use of unmanned aerial vehicles (UAVs) to locate and map subsurface tile drainage continues. Flights have been completed in Ohio and data analysis of the images continues. High frequency tile drainage volume and water quality continue in support of developing or improving prediction algorithms. Tile drainage temperature data was recently shared to support the development and assessment of structural practices to address subsurface nutrient loss.

Accomplishments
1. Controls and phosphorus reducing effects of conservation management practices in tile drained landscapes of Ohio, USA. Understanding phosphorus source and transport mechanisms within the intensive artificially (tile) drained regions of the Lake Erie watershed is at the core of meeting the binational (U.S. and Canada) 40% reduction goals to address re-eutrophication concerns within the lake. ARS scientists in Columbus, Ohio, in collaboration with university partners determined the importance of preferential flow pathways in phosphorus movement into and through tile drainage as well as the role of nutrient source and crop rotation in reducing phosphorus delivery through the tile drainage network. Preferential discharge through biopores and desiccation cracks in the soil was the primary pathway for particulate phosphorus movement in and through the tile drainage network. Inclusion of perennial crops in the crop rotation had a reducing effect on phosphorus transport while phosphorus source, liquid dairy manure or commercial synthetic fertilizer had little effect on tile drainage phosphorus loss. The findings have been shared and delivered to the USDA Natural Resource Conservation Service (NRCS), the State of Ohio-Ohio Department of Agriculture, and Lake Erie stakeholders (e.g., The Nature Conservancy, Ohio Farm Bureau Federation, university extension, and producers) and will be used to inform conservation policy. Furthermore, these findings are critical to the USDA Conservation Effects Assessment Project (CEAP) and the Long-Term Agroecosystem Research (LTAR) network sustainable intensification objectives.

2. A novel approach for distinguishing the contributions of new fertilizer and old soil phosphorus to edge-of-field phosphorus losses. Knowledge gaps about the importance of fertilizer management practices on losses of new sources (i.e., recently applied fertilizer) of phosphorus could limit the development and efficacy of P loss mitigation strategies. ARS scientists in Columbus, Ohio, in collaboration with Ohio State University researchers developed and utilized a statistical method called weighted regression on discharge and season (WRDS) to assess edge-of-field water quality data, thereby enabling estimation of the contributions of the two sources of phosphorus loss. This is the first widely applicable method that utilizes edge-of-field data and fertilizer management information to distinguish between these phosphorus sources. Initial results show that phosphorus losses are primarily dominated by old soil phosphorus sources, but certain fertilizer applications were also associated with significant phosphorus loss. As the WRDS method is applied to more datasets, the expanded results will allow for greater assessment of the effectiveness of fertilizer management approaches. The WRDS approach will be used to assess source contributions across the country using edge-of-field data as part of an ongoing NRCS project focused on legacy P, through a collaboration between ARS and university researchers. This will provide valuable insights on the sources of P losses in multiple regions of the U.S. with P loss issues, thereby informing the development of P loss mitigation efforts across the U.S.

3. Conservation Effects Assessment Project (CEAP) and Long-Term Agroecosystem Research (LTAR) cross location evaluation and assessments. Network science and research is critical to answering national scale agricultural sustainability questions with an environmental, production, and socio-economic focus. ARS scientists in Columbus, Ohio, contributed to national scale characterizations and assessments related to phosphorus dynamics and conservation practice tradeoffs. Phosphorus dynamics and controlling processes across the network vary widely and tradeoffs associated with different conservation practices should be considered prior to practice implementation. These findings have been delivered and shared with the USDA Natural Resource Conservation Service (NRCS) and other LTAR and CEAP stakeholders for use in informing conservation policy.

U.S. DEPARTMENT OF AGRICULTURE

Soil Drainage Research: Columbus, OH