Location: Soil, Water & Air Resources Research
2023 Annual Report
Objectives
Objective 1: Develop new methods and improve the characterization of carbon, nitrogen and water cycles and agrochemical dynamics to improve management opportunities for better productivity and reduced environmental impact.
Subobjective 1.1: Evaluate and compare management system influences on ET, CO2 exchange, surface energy balance partitioning and N2O emissions as a function of conventional and cover crop tillage practices.
Subobjective 1.2: Evaluate effect of drainage depth and spacing on N2O emissions.
Subobjective 1.3: Develop an improved measurement technique to quantify volatilization and atmospheric transport of agrochemicals necessary to develop and evaluate agrochemical management and remediation strategies.
Objective 2: Improve understanding of nutrient partitioning and flows from animal production to field application of manure to reduce gaps in emission inventories and improve mitigation techniques.
Subobjective 2.1: Determine NH3 and H2S emissions from swine finishing barn and manure storage based on feed inputs.
Subobjective 2.2: Assess manure injection/incorporation methods for impact on residue/surface cover, soil disturbance, and NH3 emissions.
Subobjective 2.3: Develop improved techniques for quantifying ammonia deposition near livestock production sites.
Objective 3: Identify drivers of soil and plant associated microbial community structure and function to improve soil health, nutrient use efficiency, and system resilience.
Subobjective 3.1: Test cropping system influence on soil and plant associated microbial communities.
Approach
This project will focus on knowledge gaps that remain in nutrient cycling, water use efficiency, and fate of resource inputs for cropping-livestock systems including cropping systems with highly structured canopies. Three approaches will be pursued for addressing knowledge gaps: 1) Long-term agriculture research (LTAR) networks to evaluate tillage, cover-crop, and fertilizer management influence on surface energy partitioning, water use efficiency, soil health and greenhouse gas emissions; 2) Turbulent transport mechanisms will be determined, including deposition and management practices that reduce the loss of agrochemicals from cropping systems; and 3) The partitioning of nutrients in livestock systems will be determined to evaluate management practices that reduce nutrient emissions and deposition. Field studies at LTAR network sites using eddy covariance towers will quantify evapotranspiration, carbon dioxide exchange and surface energy partitioning from reduced tillage practices with chamber studies at LTAR sites being used to quantify nitrous oxide (N2O) emissions from a range of soil and nitrogen management strategies. In other field studies, eddy covariance towers will be used to quantify water use efficiency through variable irrigation scheduling in vineyards and chamber studies used to quantify N2O emissions through intensified drainage practices. The transport parameters controlling volatile losses of agrochemicals from cropping systems based on tillage practices will be quantified using eddy covariance micrometeorology techniques to determine turbulent flux from whole fields. The relaxed eddy accumulation technique will be used to provide accurate eddy diffusivities for agrochemical vapor transport to improve agrochemical volatilization flux estimates. Riparian buffer zones will be used to quantify the fraction of agrochemicals captured by vegetative buffers to the fraction of agrochemicals volatilized. Open path ammonia (NH3) lasers will be used to quantify NH3 emissions using both barn ventilation and micrometeorology inverse dispersion modeling techniques. The partitioning of nutrients between animal, manure, and gas emissions will be quantified based on nutrient inputs (feed, animals, and residue manure) and nutrient outputs (live and dead animals, manure, and gas emissions of nitrogen (N) and sulfur (S) compounds from barns). Open path methane (CH4) and NH3 lasers and an array of NH3 passive samplers along a transect from an animal feeding operation will quantify NH3 dry deposition using both a tracer gas technique and a bidirectional NH3 flux modeling technique. The quantification of soil extracellular polymeric substances and soil aggregate stability coupled with microbial genome sequencing analysis will be used to evaluate tillage and cover-crop impact on soil health. Knowledge gained through this research will provide producers and regulatory agencies scientific data to improve the sustainability of agricultural production facilities in U.S. farming systems.
Progress Report
In support of Objective 1.1, the field monitoring of eddy covariance (EC) water vapor and carbon dioxide (CO2) and surface energy fluxes are continuing at the Long-Term Agroecosystem Research (LTAR) and AmeriFlux sites (Williams and Brooks). These long-term continuous measurement programs are quantifying water vapor and CO2 exchanges over a production field under reduced tillage operations (Williams) and conventional tillage (Brooks) in response to the need of understanding variable production management systems. At the Williams site (North field), an 8-chamber system designed to measure soil emissions of nitrous oxide (N2O) and methane (CH4) gases from this year’s corn production field were tested for the 2023 production season during the freeze-thaw period beginning in late February 2023 through the end of March 2023. The N2O and CH4 laser analyzer system was returned to the manufacturer to correct the timing sequence for synchronization with a sonic anemometer. This will allow for direct N2O, CH4, and EC measurements at the North Williams site. N2O and CH4 emissions were measured throughout the year to characterize temporal variability emissions with respect to rainfall and diurnal soil temperature.
Field measurements continued with experimental treatments at the Upper Midwest River Basin (UMRB) LTAR site in Ames, Iowa, to quantify management impacts on N2O emissions. This is the 8th year in a long-term study. All treatments were in a corn-soybean rotation and included: 1) fall chisel plow, spring disk with spring-applied anhydrous ammonia; 2) no-tillage with no cover crop with sidedress application of point injected urea ammonium nitrate (UAN); 3) no-till with winter rye cover crop and sidedress point injected UAN; 4) spring tillage with cover crop and an over-wintering winter camelina relay crop between corn and soybean (WC); and 5) a fertilized and harvested rye cover crop in a no-till system (FR). The FR treatment was initiated in the fall of 2022, to evaluate the environmental performance of a rye bioenergy or forage crop that could provide grower revenue. A manuscript was published from this data.
Work in California on the GRAPEX (Grape Remote sensing Atmospheric Profile & Evapotranspiration eXperiment) project was expanded to include more vineyards as well as an almond and olive orchard. A new design of synchronized high-frequency EC measurements for below/within vine canopies was developed and tested. This system is being deployed in a production vineyard near Madera, California, and a production almond orchard near Vacaville, California. Synchronized high-frequency measurements were conducted with remote sensing inherent optical properties activities in early July 2023 for a period of 6 weeks for a greater understanding of the vertical turbulence characteristics and transport in structured agricultural canopies and to improve remote sensing modeling of evapotranspiration (ET) for vineyards and almond orchards.
Field measurements were conducted to quantify the effects of subsurface drainage depth and intensity on N2O emissions. Drainage treatments were monitored weekly during the growing season and every other week during the fall and winter. In the 2nd year of the study, it was found that plots with subsurface drainage had 50% reduced N2O emissions compared to a no-drained treatment. While N2O emissions were higher in the undrained plots, treatments that varied drainage depth or intensity (spacing) did not influence cumulative N2O emissions. Field measurements are ongoing to determine if these trends hold in varying weather years.
In support of Objective 1.2, field measurements continued to quantify the effects of subsurface drainage depth and intensity on N2O emissions. Drainage treatments were monitored weekly during the growing season and every other week during the fall and winter. In the 2nd year of the study, plots with subsurface drainage had 50% reduced N2O emissions compared to a no-drained treatment. While N2O emissions were higher in the undrained plots, treatments that varied drainage depth or intensity (spacing) did not influence cumulative N2O emissions. Field measurements are ongoing to determine if these trends hold in varying weather years.
Research was initiated to understand patterns of N2O production in the soil profile in relation to the changes in soil moisture and water table depth affected by the drainage treatments. Subsurface gas probes, soil moisture, and oxygen sensors were installed through the soil profile to a depth of 1 m to monitor subsurface N2O concentrations. Initial results suggest that the drainage treatments have their greatest effect on soil moisture in moderate depths (30-100 cm) and that N2O production below 30 cm can contribute substantially to cumulative emissions in Iowa soils. To further investigate the hydrological controls of drainage manipulation on trace gas production and emission from soil a controlled environment experiment using intact soil columns (25 x 60 cm) was constructed. The columns are water-tight with the capacity to independently manipulate water table depth through use of a hydraulic head and have been instrumented with gas ports throughout the soil profile to quantify pore space gas concentrations, microlysimeters to measure pore water NO3 concentrations, soil moisture temperature probes, and soil tensiometers. The soil columns were collected from three soil series that vary in drainage capacity status to test the interaction of legacy soil biophysical properties that impact immediate hydrological status as influenced by current drainage.
In support of Objective 1.3, Relaxed Eddy Accumulation (REA) pesticide volatilization is a dominant vapor loss pathway for many pesticides. Turbulence is the primary transport mechanism for vapor loss from a surface to the atmosphere. The REA system takes simultaneous measurements of pesticide vapor with vertical wind motion common with turbulent transport. The REA system has been deployed since June 2022 for field monitoring at the Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) site located in Beltsville, Maryland. Results from the field collections are pending until a support Chemist position has been filled.
In support of Objective 2, the in-life phase of the study to partition nutrients in a swine finishing operation was initiated with the calibration of the cooperator’s ventilation system using multiple fan assessment numeration system (FANS) units. Ammonia (NH3) lasers and mirrors were deployed along the North-South corridors of the barn room. Sampling shelves were hung from the room ceiling at three locations along the North-South corridor. Particulate matter (PM) samplers, and sensors for hydrogen sulfide (H2S), NH3, and CO2 were deployed in the room. Patterns emerged during the first grow cycle. Concentrations of both CO2 and PM immediately increase with the introduction of animals. Both NH3 and PM concentrations were highest from late evening (after 8 pm) to early morning (before 6 am) as ventilation was lowest during those periods. Concentrations were highest for gases and PM in winter months. Winter months concentrations of NH3 averaged 25-30 parts per million volume (ppmv), CO2 averaged over 1500 ppmv (peaking at 4500), H2S averaged 0.2-0.3 ppmv (peaking at around 1 ppmv), total PM averaged 1100-1700 mg m-3 (peaking at 3500 mg m-3) compared to lower numbers in summer months. Future work includes data screening and reviewing for completeness and filling of data gaps. Ventilation data will be collected from the cooperator to correlate with concentration data for emission calculations.
Nitrogen (N) deposition research was initiated and 15 three-meter sampling posts with inverted plastic shelters and Ogawa passive samplers were deployed at a cooperator’s site in central Iowa. Researchers from multiple USDA ARS locations are developing a protocol for the micrometeorology data loggers. A micrometeorology tower was deployed in the field along with additional sensors for characterizing wind patterns, leaf moisture, canopy cover, etc. Laboratory protocol tested and validated for the following: 1) extraction of passive samplers for NH3 quantification; and 2) extraction of both vegetive and soil samples for NH3. Working on land agreements for two other farmers’ fields. Lasers and mirrors were placed on towers for determining whole facility emissions.
In support of Objective 3, a study was initiated at the UMRB LTAR site in Ames, Iowa, to assess the impact of tillage and winter cover crops on soybean root, rhizosphere, and soil microbial communities and their relationship to soil health. Soybean root, rhizosphere, and bulk soil samples were collected starting a month after planting and then continuing monthly for the growing season. Management systems tested vary in the extent of disturbance (tillage), winter carbon inputs (cover crops), and arbuscular mycorrhizal fungi host status (rye vs brassica winter cover). Samples will be used to test the hypotheses that: 1) Reduced tillage and winter cover crops will alter seasonal patterns of succession in soil and plant-associated microbial communities; and 2) soil extracellular polymeric substances and arbuscular mycorrhizal fungi (two critical soil binding factors) and soil aggregate stability will be at the greater abundance and less variable over time in treatments with reduced disturbance and continuous plant cover. Sample analysis is ongoing.
Accomplishments
1. Identified the risks of N losses under relay-and double-cropping scenarios. Relay cropping soybean with a winter oilseed crop in the Upper Midwest has potential to increase farmer revenue while providing the environmental benefits of a winter cover crop. As part of the Upper Mississippi River Basin (UMRB) Long-Term Agroecosystem Research (LTAR) Network site in Ames, Iowa, ARS researchers in the Soil Water and Air Resources and also the Agroecosystems Management Research Units compared the environmental and agronomic performance of a corn-soybean rotation with a corn-winter camelina-soybean relay cropping system to evaluate nitrous oxide (N2O) losses, nitrate (NO3) loss in subsurface drainage and crop yield. Despite the inclusion of a winter cover, the winter camelina system did not reduce nitrate leaching. Management changes to accommodate the winter camelina crop increased nitrous emissions three-fold in the camelina-soybean phase of the relay cropping system. Most of this increase occurred following fall fertilizer application to the camelina, whereas the later spring sidedress nitrogen applications resulted in only minor increases in N2O emissions. This study provides scientists and growers working to develop the winter camelina relay cropping system with new insights and tools for optimizing production and reducing nitrogen losses to the environment.
2. New tools discovered for reducing swine odors. Manure management is the first line of defense against odor at swine production facilities. ARS researchers in Ames, Iowa, and Florence, South Carolina, in collaboration with scientists from South Korea and Iowa State University, compared the effect higher recharge rates (i.e., manure dilution) have on both the microbial community composition and odor formation in pit recharge systems (PRS). The microbial community composition was influenced by both the barn source and the recharge rate of the barn. Manure odor was controlled by the manure’s total solids and pH. The microbial community had a minor role in controlling odor. Managing solids and manure pH, are the most effective means of odor control in PRS. This study provides researchers and engineers with new insights and tools for reducing odor emissions from swine finishing operations.
3. Improved water use in California orchards and vineyards. Managing irrigation in orchards and vineyards in drought-prone regions is a challenge due to their complex canopy structures. Current models describing evaporation do not adequately describe the physical processes controlling water evaporation from these surfaces. ARS scientists in Beltsville, Maryland, and Ames, Iowa, in collaboration with university scientists from Utah State University and the University of California-Davis, conducted studies to understand the unique air flow patterns over vineyards and orchards in the Central Valley of California. Almond orchards and vineyard architecture represent unique aerodynamic environments that need to be better understood to improve ET (Evapotranspiration) modeling through remote sensing. This study showed ways to improve management practices that promote greater water use efficiency in vineyards and orchards, giving growers and researchers an understanding of the role of cover crops and vine water loss and developing irrigation strategies to support reduced irrigation decisions that conserve water resources while maintaining sustainable yields and fruit/nut quality.
4. Scientists identify ways to reduce odor emissions from decaying swine carcasses during an animal health emergency. During an animal health emergency, dead animals may need to be disposed of safely to protect people, animals, and the environment. ARS researchers in Ames, Iowa, in collaboration with scientists from Digital Agronomy, LLC and Iowa State University compared how different stagging technique’s-controlled odor emissions from decaying animals. Carcasses treated with lime had reduced emissions of volatile sulfur compounds, long-chain fatty acids, and carbon dioxide (CO2). However, animals buried with shallow soil covering or wrapped in tarp material had the lowest total gas emissions while animals without any treatment had the highest gas emissions. Liming and covering animals are effective at reducing gas emissions from swine. This study provides growers and engineers with tools for reducing odor emissions from decaying swine carcasses.
5. Estimating evapotranspiration (ET) partitioning at spatial and temporal scales using sUAV (small unmanned aerial vehicle). Vineyards are considered complex agricultural landscapes because of the separation of canopy rows by exposed soil rows. Water supplies are becoming limited in irrigated agriculture, yet estimating vineyard evapotranspiration (ET) remains challenging because water can be lost independently through evaporation from the soil and separately through transpiration from the grape vines. ARS scientists in Beltsville, Maryland, and Ames, Iowa, in collaboration with university scientists from Utah State University and the University of California-Davis, strove to improve water management practices in vineyards of the Central Valley, California by determining the percentages of ET losses occurring through evaporation and transpiration. They used sUAV to estimate changes in carbon assimilation and water cycling for vineyard production. This approach estimated evaporation and transpiration losses that were scaled to the plant level by using modeling. Partitioning ET provides more accurate estimates of water losses and is also an opportunity to expand an emerging technique to include medium-resolution satellite imagery to estimate vineyard ET. This study provides growers, scientists, and engineers new tools for increasing water use efficiency at multiple spatial (small to large vineyards) scales.
6. Double cropping winter rye cover crop with soybean increases production, while simultaneously reducing nitrogen runoff in the Mississippi River Basin and Gulf of Mexico. Simultaneous goals for increasing crop production and cellulosic bioenergy production while reducing the environmental impacts of agriculture put multiple pressures on growers and conservation programs to develop and implement sustainable intensification strategies. 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, but studies addressing the management of these systems and quantifying the large-scale impacts are non-existent. ARS scientists in Ames, Iowa, and St. Paul, Minnesota, in collaboration with scientists from Iowa State University, Penn State 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 and the Mississippi River. This research will help policy makers and growers in their effort 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.
Review Publications
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.
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.
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.
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.
Volk, J.M., Huntington, J.L., Melton, F., Minor, B., Wang, T., Anapalli, S.S., Anderson, R.G., Evett, S.R., French, A.N., Jasoni, R., Bambach, N., Kustas, W.P., Alfieri, J.G., Prueger, J.H., Hipps, L., McKee, L.G., Castro, S.J., Alsina, M.M., McElrone, A.J., Reba, M.L., Runkle, B., Saber, M., Sanchez, C., Tajfar, E., Allen, R., Anderson, M.C. 2023. Post-processed data and graphical tools for a CONUS-wide eddy flux evapotranspiration dataset. Data in Brief. 48. Article 109274. https://doi.org/10.1016/j.dib.2023.109274.
Doherty, C.T., Johnson, L.F., Volk, J., Mauter, M.S., Bambach, N.E., McElrone, A.J., Alfieri, J.G., Hipps, L.E., Prueger, J.H., Castro, S.J., Alsina, M., Kustas, W.P., Melton, F.S. 2022. Effects of meteorological and land surface modeling uncertainty on errors in winegrape ET calculated with SIMS. Irrigation Science. 40:515-530. https://doi.org/10.1007/s00271-022-00808-9.
Aboutalebi, M., Torres, A., McKee, M., Kustas, W.P., Nieto, H., Alsina, M., White, W.A., Prueger, J.H., McKee, L.G., Alfieri, J.G., Hipps, L., Coopmans, C., Sanchez, L., Dokoozlian, N. 2022. Downscaling UAV land surface temperature using a coupled wavelet-machine learning-optimization algorithm and its impact on evapotranspiration. Irrigation Science. 40:553-574. https://doi.org/10.1007/s00271-022-00801-2.
Gao, R., Torres-Rua, A., Nieto, H., Zahn, E., Hipps, L., Kustas, W.P., Alsina, M., Ortiz, N., Castro, S., Prueger, J., Alfieri, J.G., McKee, L.G., White, W.A., Gao, F.N., McElrone, A.J., Anderson, M.C., Knipper, K.R., Coopmans, C., Gowing, I., Agam, N., Sanchez, L., Dokoozlian, N. 2023. ET partitioning assessment using the TSEB model and sUAS information across California Central Valley vineyards. Remote Sensing. 15(3). Article 756. https://doi.org/10.3390/rs15030756.
Fan, M.Z., Kerr, B.J., Trabue, S.L., Yin, X., Yang, Z., Wang, W. 2022. Swine nutrition and environment. In: Chiba, L.I., editor. Sustainable Swine Nutrition. 2nd edition. Hoboken, NJ. Wiley. p.547-601.
Hwang, O., Yun, Y., Trabue, S.L. 2023. Impact of Bacillus subtilis on manure solids, odor, and microbiome. Journal of Environmental Management. 333. Article 117390. https://doi.org/10.1016/j.jenvman.2023.117390.
