Research Project: Improved Management of Nutrients, Water, Agrochemicals, and Energy to Enhance Agriculture System Sustainability

Location: Soil, Water & Air Resources Research

2022 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
Objective 1. Field monitoring study of eddy covariance and surface energy fluxes were conducted at the LTAR and AmeriFlux sites (Williams and Brooks) to quantify water vapor and carbon dioxide exchanges over a production field under reduced tillage operations and conventional tillage in response to variable production management systems. At the Williams site (North field), 8 chamber systems designed to measure soil emissions of nitrous oxide (N2O) and methane (CH4) gas from this year’s soybean production field were tested and deployed to capture N2O and CH4 during the freeze-thaw period beginning in late February 2022 through the end of March 2022. A Los Gatos Research (LGR) N2O and CH4 laser analyzer was tested and evaluated in a laboratory setting in preparation for deployment to the North Williams site in July 2022. The deployment of the soil chambers and LGR trace gas analyzer represents an enhancement to the LTAR suite of surface flux measurements (water and carbon dioxide) as this is a joint project with Department of Energy (DOE) to monitor and quantify annual trace gas (N2O and CH4) fluxes in a Midwest cropping system (corn/soybean). Nitrous oxide and methane emissions will be measured throughout the year to characterize temporal variability emissions with respect to rainfall and diurnal soil temperature. Field measurements of experimental treatments were conducted at the UMRB LTAR site in Ames, Iowa, to quantify management impacts on nitrous oxide emissions. All treatments were in a corn-soybean rotation and included: 1) fall chisel plow, spring disk with spring-applied anhydrous ammonia (business as usual (BP)); 2) no-tillage with no cover crop (NTNC) 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 zero N fertilizer treatment that was otherwise managed as the NTNC (ZN). The WC system was in its sixth year and data from the entire six-year study period were compiled to compare N2O emissions and NO3 loss in drainage between the WC and BP treatments. It was found that the WC did not contribute to reduced NO3 loads in subsurface drainage. Shifts in the management system to accommodate a winter camelina relay crop increased N2O emissions during the camelina-soybean phase of the rotation. Most of this increase was associated with a small starter N fertilizer application that was provided to the camelina in the fall and with increased spring thaw emissions in the WC treatment compared to the BP. Removing the fall fertilizer application and applying N only in the spring sidedress may be an option for mitigating N2O emissions in the WC system. A manuscript has been prepared from this data. Work in California on the GRAPEX (Grape Remote sensing Atmospheric Profile & Evapotranspiration eXperiment) project was expanded to include more vineyards. The canopy vine structure influences exchange and transport processes of water vapor and carbon dioxide gas that pass through the canopy via canopy ventilation shafts produced by vine branches and leaves. A new design of synchronized high-frequency eddy covariance (EC) measurements for below/within vine canopies has been developed and tested. This system is being deployed in a production vineyard near Madera, California. Synchronized high frequency measurements will be conducted beginning in July for a period of 6 weeks to better understand the vertical turbulence characteristics and transport in structured agricultural canopies. 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 first year of the study, it was found that plots with subsurface drainage had 50% reduced N2O emissions compared to a no-drained treatment. Treatments with the most intensive drainage (narrow spacing, deeper tile line) demonstrated the greatest reduction in N2O emission. Field measurements will continue in future years 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 changing water depth influenced by the drainage treatments. Prototype gas probes were constructed to monitor subsurface N2O concentrations. Initial models performed well in terms of quantifying the concentration profile but clogged easily in the fine textured soils. Researchers are developing an alternate design that utilizes a permeable membrane to allow gas diffusion into the sample well while excluding water and sediment. Relaxed Eddy Accumulation (REA) Pesticide volatilization (vapor transport) is a dominant vapor loss pathway for many pesticides. This pathway is variable and specific to pesticide type, chemical formulation, surface target characteristics (vegetation/soil) and local meteorological conditions. Turbulence is the primary transport mechanism for pesticide vapor from a surface to the atmosphere. A new and simplified pesticide volatilization measurement system (REA) has been developed and tested in a laboratory setting. The REA system will enable simultaneous measurements of pesticide vapor with vertical wind motion common with turbulent transport. The system was ready for field deployment and final Beta testing in June 2022 at the Optimizing Production Inputs for Economic and Environmental Enhancement (OPE3) site located in Beltsville, Maryland. Objective 2. Sensors were deployed along a transect in a swine finishing barn to monitor both NH3 and hydrogen sulfide (H2S). Sensors were also co-located with cavity ring-down spectrometers (CRDS) for both NH3 and H2S. Two types of NH3 sensors were compared, one based on an electrochemical cell and the other using a bioengineered material. The H2S sensor was an electrochemical sensor. Sensors followed similar patterns of high to low concentrations along the barn transect. However, winter conditions (high air concentrations of both gases and dust) limited sensor use through either saturating sensor response (air concentration out of sensor range) or clogging of sensor fans prompting shutdown. Sensors derived from bioengineered material were more limited in measuring NH3 concentrations below 1 ppmv. Survey of seasonal laser data showed concentrations of NH3 in the winter averaged over 20 ppmv reaching as high as 100 ppmv for short periods of time (less than 15 min) in the late evening/early morning, while summer concentrations averaged less than 2 ppm but evening concentrations trended upwards (5-10 ppmv) as outside temperatures dropped. Research was initiated to measure NH3 deposition from a swine finishing operation over a two year period using the EPA (Environmental Protection Agency) STAGE model. Researchers from both USDA ARS and EPA worked to develop a sampling transect to capture prevailing wind directions based on wind rose diagrams for the area. Researchers coordinated measurements with growers and owners of a field adjacent to the swine facility. A total of 30 three-meter sampling posts with inverted plastic shelters were constructed and Ogawa passive samplers deployed. Testing of sampling protocol is on-going and lasers have been deployed to measure background NH3 gas concentrations.

Accomplishments
1. Conservation practices to reduce nitrogen (N) loss. Croplands with corn and soybean in the central United States are highly productive, but they pose a risk to the environment when N is lost as nitrate (NO3-) in subsurface drainage or as N2O emissions. Sustainable farming management practices that reduce these impacts without sacrificing yield are needed. ARS scientists in Ames, Iowa, assessed both NO3- losses and N2O emissions in cropping systems using two conservation practices: cover crops and no-till management. Overall, neither practice consistently reduced both NO3- losses and N2O emissions, indicating the two are not linked. No-till management did not affect either one. Cover crops reduced NO3- losses but not N2O emissions. Rather, N2O emissions were linked with fertilizer N applications and weather patterns. Overall, the mechanisms regulating NO3- loss and N2O emissions were not linked. The study suggests it may be necessary to combine multiple conservation practices to reduce environmental impacts in these systems.

2. Improved water use of California vineyards. Improving irrigation management is critical to ensuring water, already a scarce resource in California, is used effectively. Managing irrigation in vineyards is complicated by the unique vine canopy structure. Because of the wide rows and clumped natures of the vines, current theories and the models that rely on may not adequately describe the physical processes controlling water evaporation from vineyards. ARS scientists in Beltsville, Maryland and Ames, Iowa, in collaboration with university scientists from Utah State University and University of California, Davis, conducted a study to understand the unique airflow patterns over a vineyard in the Central Valley of California. The results show that the direction of air flow can strongly influence the vertical turbulent structure above the vines and thus the exchange of heat and moisture. Lateral air flow oriented perpendicular to the canopy row orientation will have greatest turbulent mixing and larger fluxes. The direction of air flow, which is not considered by current modeling methods, is likely to be an important factor for accurately modeling vine water loss and developing irrigation strategies to support reduced irrigation decisions that conserve water resources while maintaining sustainable yields and grape quality.

3. Alternative swine diet formulations to improve economic and environmental efficiency. Diet formulations using both non-nutritive feed additives (i.e., organic acids) and direct-fed microbials have the potential to improve the efficiency of nutrient utilization in pigs. ARS researcher in Ames, Iowa, in collaboration with university researchers from Iowa State University and researchers at Dutch State Mines Feed Company (DSM), conducted a swine feeding trial to evaluate the effects of adding benzoic acid supplemented with and without direct-fed microbials on nutrient metabolism and manure emissions of growing pigs. Feeding 0.3% benzoic acid did not affect nutrient digestibility, but reduced urinary N excretion, and improved N retention compared to the basal diet. Benzoic acid reduced urine and manure pH stabilizing NH3 in manure and reducing NH3 emissions. However, supplementing direct-fed microbials had no effect and when supplemented with benzoic acid weakened its positive effects. Information from this research will be of value to researchers, feed companies and growers looking for alternative feed ingredients to improve the environmental sustainability of swine production.

4. Origins of swine foaming pits. Foam accumulation in swine manure has been linked to explosions and flash fires from sudden and unexpected release of flammable gases, including methane. ARS researchers in Ames, Iowa, in collaboration with university scientists from Iowa State University and the University of Minnesota conducted a field study to survey physical, chemical, and biological parameters that correlate to foam accumulation at 10 farms in Iowa and Illinois. Chemical markers and microbial communities that differed between foaming and non-foaming manure were identified. Foaming barns had higher levels of both proteins and large chain fatty acids. Non-foaming manures had higher concentrations of short chain fatty acids that are known to slow formation of the methane gas a flammable gas. Several bacteria that differed in relative abundance in foaming versus non-foaming pits were identified and bacteria associated with foaming manure produced a protein material that stabilized foam. These results suggest an explanation for manure foaming in which growth of certain microorganisms leads to excessive production of methane gas and stabilizing proteins. Information in this report will be of value for growers, engineers, and scientists working on foaming issues associated with waste processing.

Review Publications
Trabue, S.L., Kerr, B.J., Scoggin, K.D., Andersen, D., van Weelden, M. 2022. Swine diets: Impact of carbohydrate sources on manure characteristics and gas emissions. Science of the Total Environment. 825. Article e153911. https://doi.org/10.1016/j.scitotenv.2022.153911.
Strom, N., Ma, Y., Andersen, D., Trabue, S.L., Chen, C., Hu, B. 2022. Eubacterium coprostanoligenes and Methanoculleus identified as potential producers of metabolites that contribute to swine manure foaming. Journal of Applied Microbiology. 132(4):2906-2924. https://doi.org/10.1111/jam.15384.
O'Brien, P.L., Emmett, B.D., Malone, R.W., Nunes, M.R., Kovar, J.L., Kaspar, T.C., Moorman, T.B., Jaynes, D.B., Parkin, T.B. 2022. Nitrate losses and nitrous oxide emissions under contrasting tillage and cover crop management. Journal of Environmental Quality. 51:683-695. https://doi.org/10.1002/jeq2.20361.
Zahn, E., Bou-Zeid, E., Good, S., Katul, G., Khaled, G., Snith, J., Chamecki, M., Dias, N., Fuentes, J., Alfieri, J.G., Caylor, K., Soderberg, K., Goa, Z., Bambach, N., Hipps, L.E., Prueger, J.H., Kustas, W.P. 2022. Direct partitioning of eddy covariance water and carbon dioxide fluxes into ground and plant components. Agricultural and Forest Meteorology. 315:10879. https://doi.org/10.1016/j.agrformet.2021.108790.
Bambach, N.E., Kustas, W.P., Alfieri, J.G., Prueger, J.H., Hipps, L., McKee, L.G., Castro-Bustamante, S., Volk, J., Alsina, M.M., McElrone, A.J. 2022. Evapotranspiration uncertainty at micrometeorological scales: The impact of the eddy covariance energy imbalance and correction methods. Irrigation Science. https://doi.org/10.1007/s00271-022-00783-1.
Bambach, N.E., Kustas, W.P., Alfieri, J.G., Gao, F.N., Prueger, J.H., Hipps, L., McKee, L.G., Castro-Bustamante, S., Alsina, M.M., McElrone, A.J. 2022. Inter-annual variability of land surface fluxes across vineyards: The role of climate, phenology, and irrigation management. Irrigation Science. https://doi.org/10.1007/s00271-022-00784-0.
Kustas, W.P., Nieto, H., Garcia-Tejera, O., Bambach, N., McElrone, A.J., Gao, F.N., Alfieri, J.G., Hipps, L., Prueger, J.H., Torres, A., Anderson, M.C., Knipper, K.R., Alsina, M., McKee, L.G., Zahn, E., Bou-Zeid, E., Dokoozlian, N. 2022. Impact of advection on two-source energy balance (TSEB) canopy transpiration parameterization for vineyards in the California Central Valley . Irrigation Science. 40:575-591. https://doi.org/10.1007/s00271-022-00778-y.
Xue, J., Anderson, M.C., Gao, F.N., Hain, C., Knipper, K.R., Yang, Y., Kustas, W.P., Yang, Y., Bambach, N., McElrone, A.J., Castro, S., Alfieri, J.G., Prueger, J.H., McKee, L.G., Hipps, L., Alsina, M. 2022. Improving the spatiotemporal resolution of remotely sensed ET information for water management through Landsat, Sentinel-2, ECOSTRESS and VIIRS data fusion. Irrigation Science. 40:609-634. https://doi.org/10.1007/s00271-022-00799-7.
Burchard-Levine, V., Nieto, H., Kustas, W.P., Gao, F.N., Alfieri, J.G., Prueger, J.H., Hipps, L.E., Bambach, N., McElrone, A.J., Castro, S., Alsina., McKee, L.G., Zhan, E., Bou-Zeid, E., Dokoozlian, N. 2022. Application of a remote-sensing three-source energy balance model to improve evapotranspiration partitioning in vineyards. Irrigation Science. 40:593-608. https://doi.org/10.1007/s00271-022-00787-x.
Nieto, H., Alsina, M.M., Kustas, W.P., Garcia-Tejera, O., Chen, F., Bambach, N., Gao, F.N., Alfieri, J.G., Hipps, L.E., Prueger, J.H., McKee, L.G., Zhan, E., Bou-Zeid, E., McElrone, A.J., Castro, S.J., Dokoozlian, N. 2022. Evaluating different metrics from the thermal-based two-source energy balance model for monitoring grapevine water stress. Irrigation Science. 40:697-713. https://doi.org/10.1007/s00271-022-00790-2.
Gao, R., Torres, A., Aboutalebi, M., White, W.A., Anderson, M.C., Kustas, W.P., Agam, N., Alsina, N., Alfieri, J.G., Hipps, L., Dokoozlian, N., Nieto, H., Gao, F.N., McKee, L.G., Prueger, J.H., Sanchez, L., McElrone, A.J., Bambach, N., Coopmans, C., Gowing, I. 2022. LAI estimation across California vineyards using sUAS multi-seasonal multi-spectral, thermal, and elevation information and machine learning. Irrigation Science. 40:731-759. https://doi.org/10.1007/s00271-022-00776-0.
Yang, F., Andersen, D.S., Trabue, S.L., Kent, A.D., Pepple, L.M., Gates, R.S., Howe, A.S. 2021. Microbial assemblages and methanogenesis pathways impact methane production and foaming in manure deep-pit storages. PLoS ONE. 16(8). https://doi.org/10.1371/journal.pone.0254730.
Bhattarai, N., D'Urso, G., Kustas, W.P., Bambach, N., Anderson, M.C., McElrone, A.J., Knipper, K.R., Gao, F.N., Alsina, M., Aboutalebi, M., McKee, L.G., Alfieri, J.G., Prueger, J.H., Belfiore, O. 2022. Influence of modeling domain and meteorological forcing data on daily evapotranspiration estimates from a Shuttleworth-Wallace model using Sentinel-2 surface reflectance data. Irrigation Science. 40:497-513. https://doi.org/10.1007/s00271-022-00768-0.