Project : USDA ARS

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Research Project: Agricultural Water Management in Poorly Drained Midwestern Agroecosystems

2020 Annual Report

Objectives
The overall objective of this project is to address the hydrologic, biogeochemical, and ecological processes and impacts of crop production agriculture and conservation practices in the poorly drained Midwestern US while sustaining increased productivity. Specific objectives include: Objective 1: Develop technology to identify the location and density of tile drainage systems. Objective 2: Characterize the coupling of hydrologic and chemical/biogeochemical processes in tile drained landscapes and its impact on water quality in the Mississippi River and Western Lake Erie Basins. Objective 3: Develop water management and treatment technologies for subsurface drainage that provide strategies to help farmers, ranchers, and other land managers adapt to climate variability and change at a variety of spatial and temporal scales. Objective 4: As part of the LTAR network, and in concert with similar long-term, land-based research infrastructure in the Midwest region, use the Eastern Corn Belt 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 Midwest region. 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 includes research and data management in support of the ARS GRACEnet and/or Livestock GRACEnet projects.

Approach
Water quantity and quality continue to be major natural resource concerns in the United States. As the pressure to produce more food, feed, fiber and fuel from our agricultural lands increases, the need for protecting soil and water resources and ecosystem services within poorly drained watersheds accelerates exponentially. In the Midwestern United States, excess water is rapidly removed through subsurface drainage and agricultural drainage ditches to facilitate agricultural crop production. Excessive levels of nutrients exported with drainage water from agricultural landscapes contribute to downstream algal blooms and hypoxic zones. Sediment, nutrient and pesticide mixtures found in waterways adjacent to agricultural production may also disrupt stream ecosystem function and have deleterious effects on aquatic biota. Information on the primary transport pathways of nutrients and the temporal delivery through these pathways at the field and watershed scales is sparse. Conservation practices (i.e., 4Rs, cover crops, drainage water management, grassed filter strips) are being implemented at a rapid rate across many watersheds to mitigate the effects of agricultural production, but their effectiveness has not been fully evaluated. The research consists of location specific and cross location research projects that investigate the impacts of agricultural land use, production management, and conservation practices on edge-of-field water quality (surface and subsurface flow pathways) and aquatic biota. Additionally, technologies and approaches to address these issues under a changing climate will be evaluated. The research will primarily be conducted in three high priority watersheds in Ohio: 1) Upper Big Walnut Creek; 2) Grand Lake St. Mary; and 3) Western Lake Erie Basin. Understanding the watershed scale transport pathways, timing, and ecological impact within these agricultural landscapes will facilitate the identification, design, and implementation of conservation practices to mitigate or reduce the environmental impact of agricultural land use

Progress Report
Objective 1 – An unmanned aerial vehicle (UAV) mounted with visible, multispectral (green, red, red edge, near infrared), and thermal infrared cameras continue to be tested for mapping subsurface drainage systems at sites in Indiana, Michigan, Minnesota, and Ohio. This large amount of accumulated imagery is providing insight on field conditions under which UAV imagery does and does not work regarding location of buried agricultural drainage pipes. A side study has been completed to determine the best time of day, from before sunrise to after sunset, to obtain thermal infrared imagery used to map drain lines. A manuscript describing this time of day impact on UAV thermal infrared mapping of subsurface drainage is complete and will be submitted to the scientific journal. Data (UAV surveys, handheld thermal imaging cameras, and stream temperature measurements) have been collected in a new study focused on evaluating the potential of using UAV multispectral and thermal infrared imagery to locate drainage system outlets in streams and ditches. Ground penetrating radar (GPR) data has also been collected at many UAV survey sites in order to further assess the capability of this technology for detecting buried drainage pipes. Working with collaborators from Aarhus University in Denmark, a manuscript is now being prepared focusing on the complimentary employment of GPR and UAV surveys for drainage mapping. A manuscript on the use of satellite imagery for determining drainage practice intensity across agricultural landscapes is pending. Objective 2 - The effect of recent phosphorus fertilizer applications on edge-of-field water quality is being analyzed using an advanced statistical approach (weighted regression on time, discharge, and season). Supplemental funds have been secured to expand the scope of the objective to characterize and model the influence of soil processes on water quality, with a specific focus on understanding how healthy soils can help mitigate nutrient losses.Steady-state nutrient addition experiments have been used to measure nutrient uptake (specifically nitrate nitrogen [NO3] and dissolved reactive phosphorus [DRP]) in tile drain flowpaths on two-stage ditch floodplains over several seasons in order to quantify nutrient removal under baseflow conditions. Longitudinal denitrification has been quantified by collecting dissolved dinitrogen (N2) gas samples from tile drain flowpaths (collaboration with ARS researchers at Oxford, Mississippi) and examined phosphorus dynamics in floodplain soils using mesocosm experiments. All the experiments have been completed; data processing and statistical analyses are ongoing Objective 3 - Previous laboratory investigation has indicated that zero valent iron has potential for use as a filter material to remove phosphate from agricultural drainage waters. The ability to regenerate zero valent iron in situ for continued phosphate removal will increase this filter material’s efficiency of use and its economic attractiveness. Additional batch and column tests were therefore conducted to evaluate the overall viability and best approach for regenerating zero valent iron for drainage water phosphate treatment. A manuscript is now in preparation. Analysis and manuscript preparation of the impact of drainage water management on hydrology and water quality from multiple field and large plot scale studies in underway. In collaboration with ARS researchers at West Lafayette, Indiana, a new field scale phosphorus removal structure was installed on a private farm. In addition, plans are underway to refit two existing structures with alternative filter media. Objective 4 - Progress continues on the conservation effects assessment project (CEAP) and the Long-Term Agroecosystem Research (LTAR) common experiment. Experiments are underway on 16 plus established paired edge-of-field sites that exist on private farms in central and northwest Ohio. Additional instrumentation is being established that includes new precipitation and weather stations and soil moisture and temperature sensors. Sites range in age from three to eight years. Assessment of among-site variability in environmental and management characteristics was completed with differences explained by fertilizer management and soil properties. Nutrient losses were more strongly related to site specific interactions between management and environmental characteristics. Additionally, an assessment of controls on subsurface nutrient losses from agricultural fields during precipitation-driven events was recently completed. Factors that both increase and decrease flow and nutrient loss were identified, thus allowing identification of management strategies to mitigate or enhance factor effects. Current practices being evaluated for addressing excess phosphorus issues include: 4Rs (right source, right rate, right time, right placement) of nutrient stewardship, cover crops, drainage water management, and structural practices. All show promise in reducing agriculture’s footprint in the Eastern Corn Belt. Placement and timing practices within the 4R framework have shown significant reductions in phosphorus loss. Cover crops have been shown to be great nitrogen scavengers; however, results related to phosphorus (specifically DRP) loss are mixed. Water quality and management data collected from agricultural fields across the edge-of-field network have been used to examine the influence of cover crops on nitrogen and phosphorus loads in subsurface drainage and surface runoff. All data has been processed and the majority of statistical analyses have been completed. Drainage water management was shown to positively reduce nitrogen loss, but the effects on phosphorus were minimal. Furthermore, the losses of phosphorus in surface runoff following drainage water management implementation tended to increase. Collaborative partnerships have been established with university partners, agencies, and nongovernment organizations (NGOs) to share and interpret the findings. Current research findings have been shared with local, state, national, and international stakeholders to identify crop production practices that can address the excess phosphorus transport that is leading to harmful and nuisance algal blooms in Lake Erie and other inland waters. The research efforts have led to opportunities for collaboration on several grants aimed at expanding the research network and scope. CEAP agreements to investigate the impact of integrated practices as well as legacy phosphorus have been established. An agreement with the University of Waterloo, Ontario, Canada, has been secured to review data and maintain the flux tower requirements of LTAR. Good progress has been made on LTAR and CEAP ecology research within the Upper Big Walnut Creek watershed, Ohio, and Cedar Creek, Indiana, evaluating ecological responses to improved water quality and conservation practices within agricultural watersheds. All joint ecology field work in the Upper Big Walnut Creek and Cedar Creek watersheds was completed in November 2019. ARS scientists at Columbus, Ohio, and West Lafayette, Indiana, and Purdue University Fort Wayne (Fort Wayne, Indiana) faculty members continue their collaboration in the fifth year of the project through the writing of peer review manuscripts. Manuscripts in preparation include documentation on: 1) the effects of sediment chemistry and sediment physical characteristics on macroinvertebrates within agricultural headwater streams; 2) the best environmental predictors of crayfish community structure in agricultural headwater streams; and 3) the relationships of air temperature and precipitation with fish biodiversity in agricultural headwater streams over a 14-year period. Progress is also being made on sampling snakes and measuring riparian habitat variables in the Upper Big Walnut Creek watershed to evaluate the effects of planting grass filter strips on terrestrial animals within riparian corridors of agricultural headwater streams.

Accomplishments
1. Quantified the hydrologic, environmental and management variability within the Lake Erie watershed and its impact on nutrient transport and water quality. Nutrient source and transport, specifically phosphorus, is at the core of understanding and addressing the re-eutrophication of Lake Erie. The recent extent and toxicity of algal blooms within the Western Lake Erie Basin (WLEB) led to the binational agreement between the United States and Canada calling for a 40% reduction in phosphorus loadings. Using collected field, stream and watershed scale data as well as simulation technologies, ARS researchers at Columbus, Ohio, and West Lafayette, Indiana, in collaboration with various university partners quantified the hydrologic, environmental, and management variability within the WLEB and related those findings to nutrient transport and water quality. Variation in field scale water quality across the WLEB was in large part explained by differences in management practices and soil properties. In-stream sediment phosphorus was identified as a significant source of downstream phosphorus delivery. Changes in precipitation amount and intensity over time have significantly increased phosphorus delivery from several Lake Erie tributaries. Simulation technologies were able to capture the measured variability and thus can be used to assess the impacts of different conservation management practices. The findings have been shared and delivered to Lake Erie stakeholders (e.g., Natural Resource Conservation Service, The Nature Conservancy, Farm Bureau, and producers) and should help to inform conservation policy. Furthermore, these findings are critical to the Long-Term Agroecosystem Network (LTAR), specifically the common experiment and sustainability of agricultural intensification.

2. Unmanned aerial vehicle (UAV) surveys improve accuracy of UAV mapped subsurface drainage systems. Based on both economic and environmental considerations, there is a need for effective, efficient, and nondestructive methods for mapping agricultural subsurface drainage systems. UAV surveys, especially with thermal infrared (TIR) cameras, have shown promise for drainage pipe detection, but positional accuracy of TIR imagery is usually not sufficient to produce useable drainage system maps. Visible bandwidth UAV imagery often does not detect drainage pipes as well as TIR; however, many UAV configurations using high-resolution visible bandwidth cameras are real time kinematic/global navigation satellite system (RTK/GNSS) compatible and therefore offer excellent positional accuracy. ARS researchers at Columbus, Ohio, along with University of Tennessee partners demonstrated that a UAV visible bandwidth survey with RTK/GNSS capability can be used to produce ground control points that improve the positional accuracy of subsurface drainage maps generated by UAV TIR imagery, greatly improving accuracy and efficiency with which drainage maps are generated. Consequently, integrating these two different types of UAV imagery surveys, can in many cases, be a more efficient and less destructive alternative for subsurface drainage mapping than trenching with construction equipment or using a hand-held tile probe. This technology is valuable to drainage contractors for use in retrofitting/repairing existing subsurface drainage systems, and for those conducting environmental risk assessments based on drainage practice intensity within agricultural landscapes.

3. Unmanned aerial vehicle (UAV) imagery can be employed to map agricultural subsurface drainage systems in the Midwest United States. Based on both economic and environmental considerations, there is a need for effective, efficient, and nondestructive methods for mapping agricultural subsurface drainage systems. Aerial surveys using a UAV with visible-color (VIS-C), multispectral (MS), and thermal infrared (TIR) cameras were conducted by ARS researchers at Columbus, Ohio, at 29 agricultural field sites in the Midwestern United States to evaluate the potential of this technology for mapping buried drainage pipes. Although TIR generally worked best, there were sites where either VIS-C or MS proved more effective than TIR for mapping subsurface drainage systems. Therefore, to ensure the greatest chance for successfully determining drainage pipe patterns in a field, UAV surveys need to be carried out with all three types of cameras, VIS-C, MS, and TIR. Timing of UAV surveys relative to recent rainfall can sometimes have an important impact on drainage pipe detection results. Furthermore, linear features representing drain lines and farm field operations can be confused with one another and are often both depicted on site aerial imagery. The overall results and extracted key findings from this study clearly indicate that VIS-C, MS, and TIR imagery obtained with UAVs have significant potential for use in mapping agricultural drainage pipe systems. This technology is valuable to drainage contractors for use in retrofitting/repairing existing subsurface drainage systems, and for those conducting environmental risk assessments based on drainage practice intensity within agricultural landscapes.

4. Phosphorus losses from cropland are exacerbated by high runoff. Excess water in Midwestern croplands must be transported away from fields through surface runoff or tile drainage, and in the process carries phosphorus stored in agricultural soils to the Great Lakes and Gulf of Mexico where it causes water quality issues. Relationships between water drainage and phosphorus transport can provide insight into the climate, soil, and management factors that drive this issue. ARS researchers at Columbus, Ohio, investigated patterns of water volume and phosphorus concentrations of runoff from fields in Ohio. Larger volumes of runoff resulted in higher phosphorus concentrations which highlighted the primary importance of addressing P losses during large precipitation events. These findings will guide future research efforts into factors controlling water quality and can also help advance water quality modeling.

5. Documented that the frequency and severity of crayfish injuries was more strongly influenced by physical habitat quality and biotic factors than water quality in agricultural headwater streams. Agricultural conservation practices are frequently used to reduce the impacts of agriculture on stream ecosystems. The ecological effect of many conservation practices on the aquatic biota has not been evaluated. Information on the biota-habitat relationships within agricultural streams can provide predictions about the ecological effects of conservation practices. University scientists from Bowling Green State University and Purdue University Fort Wayne and ARS Scientists from Columbus, Ohio, and West Lafayette, Indiana, evaluated the relationships of the frequency and severity of injuries of common stream invertebrate (crayfish) with physical habitat quality, water quality, and crayfish abundance within agricultural headwater streams. The frequency and severity of crayfish injuries was most strongly influenced by crayfish abundance and physical habitat quality, but not water quality. These results suggest that conservation practices that lead to increases in the diversity of water depth, water velocity, and substrate types in agricultural streams in the Midwestern United States are more likely to positively benefit crayfishes than water quality improvements. These results will assist state agencies, federal agencies, non-profit groups, and consulting agencies involved with conservation and management of macroinvertebrates as well as those involved with managing agricultural watersheds.

U.S. DEPARTMENT OF AGRICULTURE

Soil Drainage Research: Columbus, OH