Location: Agroecosystems Management Research
2023 Annual Report
Objectives
Objective 1: Evaluate trends in hydrology and water quality in agricultural watersheds managed with current production practices. The research utilizes georeferenced data relating to landuse, terrain, cropping and animal production, observable use of conservation practices, and climate and meteorological data.
1.A: Document changes in land use, conservation practices, and climate as drivers of water quality trends in three Iowa watersheds.
1.B: Utilize new stream monitoring technology and terrain analyses to document stream bank movement and water quality changes along the SFIR, as related to adjacent land use and extreme weather events.
Objective 2: In collaboration with other Long-Term Agroecosystem Research (LTAR) network sites, identify practices and factors that influence the effectiveness of conservation practices.
2.A: Compare the effects of ASP cropping system as part of the LTAR Common Experiment with other C-S cropping systems on targets such as N loss to drainage.
2.B: Determine crop water use using UAV imagery.
Objective 3: Assess and improve models and remote sensing to characterize fields and watersheds.
3.A: Assess and improve modeling of Midwest conservation practices for sustainable intensification of agriculture.
3.B: Assess and improve mapping and analysis of subsurface drainage (e.g., patterns and intensity) using techniques from UAS and satellite imagery from several Midwest locations including four LTAR-drainage workgroup sites (Ames, St. Paul, W. Lafayette, Columbus).
Approach
This project will investigate the effects of agricultural management practices at field and watershed scales, investigate the dynamics of watershed hydrology, and assess and improve tools to characterize agricultural systems.
Under the first objective, watershed studies will evaluate practices that can reduce loss of nitrate-nitrogen and phosphorous from cropped fields. These practices include saturated buffers, bioreactors, and blind surface inlets to subsurface drainage. Trend analysis will be conducted on long term records in the watershed studies to gain insight on water quality and streamflow variability over time. Streambank movement in these watersheds will be monitored with remote sensing.
Under the second objective, field studies will be conducted as part of the Long-Term Agroecosystem Research network that will support research to sustain or enhance agricultural production and environmental quality in the Upper Mississippi River Basin (UMRB) region.
The third objective will employ a mix of modeling and remote sensing studies to evaluate conservation practices and subsurface drainage systems.
A breadth of watershed monitoring, remote sensing, controlled experiments in field and laboratory, and modeling techniques will be employed in the research. Publications, tools for conservation planning, and databases available to other scientists will be produced. Results are intended to enable agriculture to better manage water resources for multiple needs; particularly, in the UMRB.
Progress Report
In support of Objective 1, water flow, water quality, and meteorological data were obtained from the experimental watersheds with laboratory measurements completed for the 2022 sampling season. Sampling and analysis for the 2023 year are underway. Data from these watersheds were added to the Sustaining the Earth's Watersheds, Agricultural Research Data System database supporting the Conservation Effects Assessment Project (CEAP) and the Long-Term Agroecosystem Research (LTAR) network. Also related to Objective 1, delays in hiring a Southfork Watershed Alliance (SFWA) coordinator delayed plans for installation of six new saturated buffers as part of Batch and Build effort in the South Fork Watershed. The Batch and Build model first implemented by the Conservation Infrastructure initiative in 2021, co-led by Iowa Agriculture Water Alliance and Iowa Department of Agriculture and Land Stewardship to drastically scale up the number of saturated buffers and bioreactors in Iowa. Nevertheless, preparation for installation of the six new saturated buffers are currently underway and include purchasing of automated Smart Drainage System water control structures for continuous monitoring of water flow as well as purchasing of nitrate sensors for continuous measurements of nitrates in the tile discharge. In addition, work on existing saturated buffers continues as water samples are collected on a biweekly basis and analyzed for nitrates. Deep soil cores (0-48 inches) were collected in the fall of 2022 from two long term saturated buffer sites and are being analyzed for inorganic nitrogen (N) and total carbon (C) and N. An ORISE Fellow has been analyzing data and modeling saturated buffers impact using the Soil and Water Assessment Tool model (SWAT). Lastly, unmanned Aerial System (UAS) Light Detection and Ranging mapping missions were flown two times along sites in the South Fork Iowa River reach areas adjacent to stream flow monitoring stations during the Spring of 2023, to document stream bank migration and retreat due to erosion. We are partnering with the Columbia, Missouri, ARS location and other ARS locations to analyze climate and discharge data collected from at least four LTAR/CEAP watersheds within the Mississippi River Basin (Iowa, Missouri, Oklahoma, and Mississippi). The objective of this research is to determine whether long term climate and river/stream discharge trends are consistent with Global Climate Models (GCMs). Partnering with multiple ARS locations will allow the potential to analyze multi-location trends in long-term records (>50 years) of precipitation, temperature, and discharge. Preliminary results show that trends are consistent with the GCMs.
In support of Objective 2, drainage water samples from the Kelley field site near Ames, Iowa, are being collected and analyzed as part of LTAR efforts to quantify the effect of cropping systems, conservation practices and N management on water quality and nitrous oxide emissions. Nitrous oxide emissions are being monitored weekly. Nitrate, phosphorus (P), sulfur, and potassium losses in tile drainage are being measured weekly during flow events. Preliminary 2023 water quality data collected shows nitrate-N concentrations taken from the "aspirational” cropping system (includes relay intercropping of winter camelina between corn and soybean) were no different than nitrate coming from conventional corn soybean management. Conservation practices, such as implementation of annual rye cover crop and in-situ woodchip denitrification bioreactors, were shown to significantly reduce nitrate loss due to leaching relative to conventional practices. Specifically, corn and soybean managed under no-till with rye cover crop and no-till with in-situ woodchip denitrification wall reduced N loss 59 and 58% compared with conventional practices. Cropping system had no significant effect on concentration of orthophosphate, total dissolved P, potassium, or sulfur in the drainage.
In support of Objective 3, data is continuing to be gathered from the Kelley field site near Ames, Iowa, to parameterize and test the SWAT model to simulate effect of winter cover crops on N loss to drainage. Preliminary model runs appear promising with reasonably simulated N loss to drainage and crop growth compared to field observations. We are also partnering with the El Reno, Oklahoma, ARS location to provide a calibrated SWAT model to test aspirational practices across several LTAR sites. Aspirational practices for Ames in this context will likely include winter rye cover crop harvested as a bioenergy feedstock. In addition, UAS flights have continued at the Kelley field site to help identify subsurface drainpipe configurations. Several flights have been completed. While techniques have been modified to increase the quality of the products, field drainpipes have not been detected. With continued monitoring, drainpipes are expected to be detected when conditions are more favorable (e.g., soil water content, drainage rate, and surface crop residue and growth stage). However, the most favorable conditions are not yet fully understood. A methodological framework is being developed to determine optimal conditions for drainpipe detection in the U.S. Midwest.
Accomplishments
1. Double cropping winter rye cover crop with soybean increases bioenergy production while simultaneously reducing nitrogen loss to the Mississippi River Basin and Gulf of Mexico. Simultaneous goals to increase crop production, increase cellulosic bioenergy production, and reduce the environmental impacts of agriculture without reducing producer profits puts multiple pressures on growers and conservation programs. Double-cropping winter rye cover crops with soybean in the North Central U.S. could help with the global effort to sustainably intensify agriculture and increase cellulosic energy production. However, studies addressing the management of this system and quantifying the large-scale impacts are limited to non-existent. ARS scientists in Ames, Iowa, Maricopa, Arizona, and St. Paul, Minnesota, in collaboration with scientists from Iowa State University, Pennsylvania State University, Purdue University, and McGill University completed a field and modeling study that suggested harvesting fertilized rye cover crop biomass before planting soybean is a promising practice for the North Central U.S. to cost effectively maximize total crop production and net energy production while reducing N loss to drainage. For example, harvesting fertilized rye before soybean planting in five North Central U.S. states can reduce nitrogen (N) loads to the Mississippi River and Gulf of Mexico by nearly 30% relative to no rye and provide more than three times the 2022 U.S. cellulosic biofuel production without reducing primary crop production. This research will help in the efforts to design and implement effective management systems to reduce N loads to the Mississippi River Basin and Gulf of Mexico while increasing cellulosic bioenergy production.
2. Saturated buffers demonstrated to serve as a successful practice to reduce nitrate at the edge-of-field and reduce runoff - preventing nitrogen leaching. A long-term collaboration between ARS and Iowa State University scientists in Ames, Iowa, was recognized by FLC with an Impact Award for the development of a new edge-of-field conservation practice. Agricultural soils of the Upper Midwest are highly productive; however, poor drainage can contribute to prolonged saturated conditions that negatively impact crop production. While artificial subsurface drainage (tile) can support agricultural land use, nitrate loss in drainage is a major source of surface water pollution. A novel approach for reducing nitrate loss is to intercept a field tile where it crosses a riparian buffer and divert a fraction of the flow to shallow groundwater within the buffer. This practice is called a saturated buffer, and comprehensive monitoring at a network of sites has demonstrated its utility as an effective edge-of-field nitrate reduction practice. The research results have contributed to the Central Iowa Water Quality Infrastructure Project to establish over 50 saturated buffers and bioreactors in 2021 via a new framework to streamline and scale up adoption by farmers. In addition, the Iowa Department of Agriculture and Land Stewardship partnering with the city of Ames and the Story County Soil and Water Conservation District have installed about 25 edge-of-field conservation practices in 2022, including bioreactors and saturated buffers. This technology is quickly becoming accepted across the Midwest “tile” drained area benefiting farmers, policymakers, and the general public that seek cost-effective ways to improve water quality.
3. Scientists discover relay-cropping may actually increase risk of nitrogen oxide emissions. Relay cropping soybean with a winter oilseed crop is a promising sustainable intensification strategy for the corn-soybean rotations of the Upper Midwest and is intended to increase farmer revenue and provide environmental benefits of a winter cover crop. ARS researchers at the LTAR site in Ames, Iowa, compared a business-as-usual corn-soybean rotation with an aspirational corn-winter camelina-soybean relay cropping system to evaluate nitrous oxide losses, nitrate losses in subsurface drainage, and crop yield. Despite the inclusion of a winter crop, the camelina system did not reduce nitrate leaching and increased nitrous oxide emissions. The limited fall and early spring biomass accumulation and nitrogen uptake with a fall nitrogen starter fertilizer application contributed to these findings. Publication of this research was the first report of measured nitrogen losses from an oilseed relay cropping system in the Upper Midwest. Identifying these risks resulted in ARS scientists refining the relay-crop system to improve environmental outcomes. This research will help in the efforts to design and implement effective relay-crop systems to reduce nitrogen losses to the environment while increasing production.
Review Publications
Wyssmann, M.A., Papanicolaou, A.N., Kyriakopoulos, T. 2023. Semi-theoretical model for mean sediment resting time of spherical particles: the role of hydrodynamic impulses and sphere size nonuniformity. Acta Geophysica. https://doi.org/10.1007/s11600-022-01010-3.
Wilson, C.G., Schilling, K.E., Papanicolaou, A.N. 2022. Evaluating causal factors that influence the spatial and temporal variability of streambank erosion in Iowa. Journal of the ASABE. 65(6):1465-1473. https://doi.org/10.13031/ja.14894.
Malone, R.W., O'Brien, P.L., Herbstritt, S., Emmett, B.D., Karlen, D.L., Kaspar, T.C., Kohler, K., Radke, A.G., Lence, S.H., Wu, H., Richard, T.L. 2022. Rye-soybean double-crop: planting method and N fertilization effects in the North Central US. Renewable Agriculture and Food Systems. 37(5):445-456. https://doi.org/10.1017/S1742170522000096.
Malone, R.W., Radke, A.G., Herbstritt, S., Wu, H., Qi, Z., Emmett, B.D., Helmers, M., Schulte, L., Feyereisen, G.W., O'Brien, P.L., Kovar, J.L., Rogovska, N.P., Kladivko, E.J., Thorp, K.R., Kaspar, T., Jaynes, D.B., Karlen, D., Richard, T. 2023. Harvested winter rye energy cover crop: multiple benefits for North Central US. Environmental Research Letters. 18(7). https://doi.org/10.1088/1748-9326/acd708.
Phillips, C.L., Tekeste, M., Ebrahimi, E., Logsdon, S.D., Malone, R.W., O'Brien, P.L., Emmett, B.D., Karlen, D.L. 2023. Thirteen-year stover harvest and tillage effects on soil compaction in Iowa. Agrosystems, Geosciences & Environment. 6(2). Article e20361. https://doi.org/10.1002/agg2.20361.
Herbstritt, S., Richard, T.L., Lence, S.H., Wu, H., O'Brien, P.L., Emmett, B.D., Kaspar, T.C., Karlen, D.L., Kohler, K., Malone, R.W. 2022. Rye as an energy cover crop: Management, forage quality, and revenue opportunities for feed and bioenergy. Agriculture. 12(10). Article 12101691. https://doi.org/10.3390/agriculture12101691.
Emmett, B.D., O'Brien, P.L., Malone, R.W., Rogovska, N.P., Kovar, J.L., Kohler, K., Kaspar, T.C., Moorman, T.B., Jaynes, D.B., Parkin, T.B. 2022. Nitrate losses in subsurface drainage and nitrous oxide emissions from a winter camelina relay cropping system reveal challenges to sustainable intensification. Agriculture, Ecosystems and Environment. 339. Article 108136. https://doi.org/10.1016/j.agee.2022.108136.
Hatfield, J.L., O'Brien, P.L., Wacha, K.M. 2023. Soil health impacts on water and nutrient use efficiency. In: Bakhru A., editor. Nutrition and Integrative Medicine for Clinicians. Boca Raton, Florida. CRC press. p.279-286.
Hatfield, J.L., O'Brien, P.L., Wacha, K.M. 2022. Climate fluctuations and soil hydrology. In: Blanco, H., Kumar, S., Anderson, S.H., editors. Soil Hydrology in a Changing Climate. Clayton, Autralia: CSIRO Publishing. p.19-38.
Wacha, K.M., Philo, A., Hatfield, J.L. 2022. Soil energetics: A unifying framework to quantify soil functionality. Agrosystems, Geosciences & Environment. 5(4). Article e20314. https://doi.org/10.1002/agg2.20314.
