Research Project: Evaluating Management Strategies to Increase Agroecosystem Productivity, Resilience, and Viability

Location: Agroecosystem Management Research

2023 Annual Report

Objectives
Objective 1: Evaluate impacts of conservation tillage practices and crop diversity on soil carbon sequestration, greenhouse gas emissions, and soil microbial communities. Subobjective 1A: Determine how crop rotation diversification affects soil organic carbon. Subobjective 1B: Quantify soil greenhouse gas emissions from different management and cropping systems. Subobjective 1C: Quantify soil microbial communities from different management and cropping systems. Objective 2: Quantify the impacts of modified management practices of integrated crop-livestock systems to improve agricultural productivity in a temperate environment.. Subobjective 2A: Determine soil physical, chemical, and biological quality changes under integrated crop-livestock (ICL) systems. Subobjective 2B: Determine soil greenhouse gas fluxes from ICL systems. Objective 3. Quantify water management and nutrient management effects on the productivity of crop and feedstock production systems. Subobjective 3A: Determine water use in annual and perennial systems used for bioenergy. Subobjective 3B: Evaluate nitrogen use efficiency on long-term cropping systems. Objective 4: Operate and maintain the Platte River – High Plains Aquifer Long-Term Agroecosystem Research (LTAR) network site using technologies and practices agreed upon by the LTAR leadership. Contribute to the LTAR working groups and common experiments as resources allow. Submit relevant data with appropriate metadata to the LTAR Information Ecosystem. Subobjective 4A: Establish and instrument LTAR research sites. Subobjective 4B: Contribute data to the LTAR database as requested.

Approach
An integrated, systems approach is needed to improve agricultural systems toward greater sustainability to meet societal demands for food, feed, fiber, and fuel. Soil and crop management strategies that optimize the capacity of cropland and grassland soils to store carbon while minimizing greenhouse gas emissions from nitrogen fertilizer and other management practices are required. Past research has increased crop nutrient and water use efficiencies through best management practices coupled with the development of better germplasm. More improvements are required to adapt to climate variability and change, increased competition for limited water resources, and increased demand by a growing population and improved standard of living. Further, a better understanding of how genetics, management, and environmental conditions affects soil organic carbon dynamics, including impacts on soil microbial structure and function, is needed to improve or maintain critical soil functions and associated ecosystem services. Research activities will investigate the role of agronomic practices on soil properties and greenhouse gas fluxes (Objective 1), quantify productivity and soil quality in integrated crop-livestock systems (Objective 2), determine nutrient and water management effects on crop and feedstock production systems (Objective 3), and operate and maintain the Platte River—High Plains long-term agroecosystem research site in collaboration with University of Nebraska-Lincoln (UNL) (Objective 4). Although each objective has a specific research focus, we recognize that a systems-based approach is required and will integrate these research objectives, as needed, to improve our current understanding of integrated agricultural systems. Results will be shared with producers, consultants, extension educators, state and federal regulatory agency personnel, and other scientists. Products resulting from this project plan will contribute to improved soil, crop, and integrated crop-livestock management relevant approaches and tools applicable to temperate regions within sub-humid and semi-arid environments.

Progress Report
This is the final report for Project 3042-11210-003-000D “Evaluating Management Strategies to Increase Agroecosystem Productivity, Resilience, and Viability.” Substantial research results were obtained on all four objectives and their sub-objectives. Under Objective 1, substantial progress was made in the project plat that determined crop rotation diversity had a greater effect on soil organic carbon than nitrogen fertilizer rates and crop rotation diversity increased the amount of soil organic nitrogen availability and the rate of organic nitrogen cycling. Crop diversification also increased corn yields over time and under optimum growing conditions. Results highlight how more diverse crop rotations contribute to improved soil health and crop productivity. Further, ARS scientists determined that long-term (16 years) switchgrass systems mitigate Greenhouse Gas (GHG) emissions during the feedstock production phase compared to GHG-neutral continuous corn under conservation management. Increased soil organic carbon was the major GHG sink in all feedstock systems, but net agronomic GHG outcomes hinged on soil nitrous oxide emissions controlled by nitrogen fertilizer rate. For Objective 2, results indicate that incorporating perennial grasses into integrated crop-livestock systems will provide effective GHG mitigation outcomes. Corn residue grazing, primarily by beef cattle, provides a simple and economical practice to integrate crops and livestock. ARS scientists in collaboration with university colleagues, determined that annual gross value for grazing corn residue for cattle producers was $191 million in Kansas, Nebraska, South Dakota, and North Dakota. Substantial progress has been made for Objective 3. ARS researchers determined how water use efficiency can vary through time and how water use efficiency variability differs between an annual crop (e.g., corn) and a perennial crop (e.g., switchgrass). Switchgrass was found to be more sensitive to increased nitrogen than corn when examining responses to water use efficiency. We determined the corn residue removal effects on grain yield under different nitrogen fertilizer rates, irrigation rates and amelioration practices to maintain soil carbon (C) and minimize soil erosion. Results highlight that residue removal increased grain yield and N uptake compared with no residue removal. Grain N concentration was higher with corn residue removal than residue retained. For Objective 4, field and replicated plot-based experiments have been initiated for the Platte River/High Plains Aquifer Long-Term Agroecosystem Research Network. The primary goal of the Long-Term Agroecosystem Research Network is to develop and share science-based findings with producers and stakeholders. The Platte River/High Plains Aquifer Long-Term Agroecosystem Research Network represents the integrated systems found in the central Plains. Experiments consist of annual row crop systems with differing levels of crop rotation diversity and precision agriculture technologies and pasture systems comparing different management strategies. The Long-Term Agroecosystem Research Network field experiments are in south central Nebraska and eastern Nebraska under both irrigated and rainfed conditions. Field experiments are instrumented to measure important soil-crop-atmosphere parameters. Baseline soil samples have been collected and archived for future analysis.

Accomplishments
1. Crop diversity improves soil resources and functionality. How crop rotation diversity affects soil organic matter and soil microbial communities is still unclear. ARS scientists in Lincoln, Nebraska, found that crop rotations affected soil organic matter chemistry and that soil organic matter sources were largely microbial in origin. Crop rotation diversification also increased agricultural resilience to adverse climate conditions, particularly drought. Rotational diversification was beneficial to corn at low nitrogen fertilization, indicating enhanced nitrogen use efficiency. Crop rotation diversity promotes soil nitrogen cycling and can decrease the dependency on external nitrogen inputs while still maintaining crop productivity and decreasing the risk of nitrogen losses into the environment. Results highlight how diverse crop practices can contribute to improved soil health and crop productivity on U.S. farms.

2. Cover crop decision support system. Cover crops provide numerous agroecosystem services such as increased soil health and conservation while increasing water and nutrient use efficiency. Cover crop performance depends on cover crop type, climate, soil, and management. ARS researchers in Lincoln, Nebraska, have improved cover crop decisions for producers to make informed decisions on different aspects of cover crops, particularly, species selection and performance under various climate and management scenarios. Improvements on the cover crop decision support system is on-going to increase the decision-making capabilities for producers and enhance the adoption of cover crops.

3. Perennial grass energy crop effects on soil carbon and nitrogen. Incorporating native perennial grasses on marginal cropland can increase agroecosystem resilience by diversifying rural energy production and improving soil health. An ARS researcher in Lincoln, Nebraska, conducted a five-year study that evaluated soil organic carbon, total soil nitrogen, and biomass for native perennial warm-season grasses with different nitrogen fertilizer rates compared to no-till continuous-corn. Neither soil organic carbon nor total soil nitrogen changed over time under either the warm-season grasses or corn. Both soil organic carbon and total soil nitrogen were generally greater in the low-diversity mixture compared to big bluestem. The effect of nitrogen fertilizer on warm-season grass biomass was inconsistent. Biomass was generally greater in the low-diversity mixture after the first harvest year. Growing native perennial grasses on marginal cropland can maintain soil organic carbon and total soil nitrogen stocks while providing a significant source of biomass to be used in energy production or in integrated livestock systems benefiting U.S. producers.

Review Publications
Breza, L.C., Mooshammer, M., Bowles, T.M., Jin, V.L., Schmer, M.R., Thompson, B., Grandy, S.A. 2022. Complex crop rotations improve organic nitrogen cycling. Soil Biology and Biochemistry. 177. Article 108911. https://doi.org/10.1016/j.soilbio.2022.108911.
Birru, G.A., Shiferaw, A., Tadesse, T., Schmer, M.R., Jin, V.L., Wardlow, B., Koehler-Cole, K., Awad, T., Beebout, S.E., Tsegaye, T.D., Kharel, T.P. 2023. Simulated impacts of winter rye cover crop on continuous maize yield and soil parameters. Agronomy Journal. 115(3):1114-1130. https://doi.org/10.1002/agj2.21291.
Mazis, A., Awada, T., Erickson, G., Wienhold, B.J., Jin, V.L., Schmer, M.R., Suyker, A., Zhou, Y., Hiller, J. 2023. Synergistic use of optical and biophysical traits to assess Bromus inermis pasture performance and quality under different management strategies in Eastern Nebraska, US. Agriculture, Ecosystems and Environment. 348. Article 108400. https://doi.org/10.1016/j.agee.2023.108400.
Li, L., Ma, L., Qi, Z., Fang, Q., Harmel, R.D., Schmer, M.R., Jin, V.L. 2023. Measured and simulated effects of residue removal and amelioration practices in no-till irrigated corn (Zea mays L.). European Journal of Agronomy. 146. Article 126807. https://doi.org/10.1016/j.eja.2023.126807.
Ramirez II, S., Schmer, M.R., Jin, V.L., Mitchell, R., Eskridge, K. 2023. Near-term effects of perennial grasses on soil carbon and nitrogen in eastern Nebraska. Environments. 10(5):80. https://doi.org/10.3390/environments10050080.
Smith, M.E., Vico, G., Costa, A., Bowles, T., Gaudin, A.C.M., Hallin, S., Watson, C.A., Alarcon, R., Berti, A., Blecharczyk, A., Francisco, F.J., Culman, S., Deen, W., Garcia, A.G., Garcia-Diaz, A., Plaza, E.H., Jonczyk, K., Jack, O., Lehman, R.M., Montemurro, F., Morari, F., Onofri, A., Osborne, S.L., Pasamon, J.L.T., Sandstrom, B., Santin-Montanya, I., Sawinski, Z., Schmer, M.R., Stalenga, J., Strock, J., Tei, F., Topp, C.F.E., Ventrella, D., Walker, R.L., Bommarco, R. 2023. Increasing crop rotational diversity can enhance cereal yields. Communications Earth & Environment. 4(1). Article 89. https://doi.org/10.1038/s43247-023-00746-0.
Hoover, D.L., Abendroth, L.J., Browning, D.M., Saha, A., Snyder, K.A., Wagle, P., Witthaus, L.M., Baffaut, C., Biederman, J.A., Bosch, D.D., Bracho, R., Busch, D., Clark, P., Ellsworth, P.Z., Fay, P.A., Flerchinger, G.N., Kearney, S.P., Levers, L.R., Saliendra, N.Z., Schmer, M.R., Schomberg, H.H., Scott, R.L. 2022. Indicators of water use efficiency across diverse agroecosystems and spatiotemporal scales. Science of the Total Environment. 864. Article e160992. https://doi.org/10.1016/j.scitotenv.2022.160992.
Mehmet, B.E., Clay, D.E., Resse, C.L., Westhoff, S., Ownes, R., Birru, G.A., Wang, Z. 2022. Increased rainfall may place saline/sodic soils on the tipping point of sustainability. Journal of Soil and Water Conservation Society. 77(4):418-425. https://doi.org/10.2489/jswc.2022.00131.
Mersha, Z., Birru, G.A., Hau, B. 2023. Light and electron microscopy studies elucidating mechanisms of tomato leaf infection by Pseudocercospora fuligena. Plant Pathology. 39(2):181-190. https://doi.org/10.5423/PPJ.OA.06.2022.0082.
Liang, K., Zhang, X., Liang, X., Jin, V.L., Birru, G.A., Schmer, M.R., Robertson, P.G., McCarty, G.W., Moglen, G.E. 2023. Simulating agroecosystem soil inorganic nitrogen dynamics under long-term management with an improved SWAT-C model. Science of the Total Environment. 879. Article 162906. https://doi.org/10.1016/j.scitotenv.2023.162906.