Location: Agroecosystem Management Research
2020 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
Progress has been made in all four objectives and subobjectives. Under Objective 1A, substantial progress has been made with research that determined crop rotation diversity increases soil organic carbon more than nitrogen fertilizer rates. For Objective 1B, soil greenhouse gas data have been collected using static chamber methodology and data have been summarized and presented. Data show that tillage practices increase nitrous oxide fluxes more than no-till practices in a corn-soybean system. Under Objective 1C, metagenomic/metatranscriptome assembly data have been completed. For Objective 2A, substantial progress has been made with soil samples completed and archived. Soil samples have been summarized for soil biological property analysis to better understand regional impacts from current integrated-crop livestock management practices. For Objective 2B, soil greenhouse gas emissions have been conducted and completed in perennial and annual systems.
For Objective 3A, soil matric potential water sensor values have been summarized in perennial grass and corn treatments. Under Objective 3B, substantial progress has been made documenting 8 years of nitrogen use efficiency data and grain yield in an irrigated continuous corn system. In addition, data have been presented to local farmers on proper corn stover management. For Objective 4A, baseline soil data have been analyzed and checked for quality control. Under Objective 4B, existing business-as-usual experimental sites are fully instrumented to measure carbon dioxide flux, weather data, and collect phenocam data.
Accomplishments
1. Substantial climate mitigation benefit. Substantial climate mitigation benefit. Management controls the net greenhouse gas outcomes of growing bioenergy feedstocks on marginally productive croplands. Bio-based energy is key to developing a globally sustainable low-carbon economy. Lignocellulosic feedstock production on marginally productive croplands is expected to provide substantial climate mitigation benefits, but long-term field research comparing greenhouse gas (GHG) outcomes during the production of annual versus perennial crop-based feedstocks is lacking. ARS scientists in Lincoln, Nebraska, and Fort Collins, Colorado, determined that long-term (16 years) switchgrass systems mitigate 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. This field study is the first to demonstrate that annual crop and perennial grass systems respectively maintain or mitigate atmospheric GHG contributions during the agronomic phase of bioenergy production, providing flexibility for land-use decisions on marginally productive croplands.
2. Agricultural resilience. Crop rotation diversification increases agricultural resilience to adverse climate conditions. Increased weather extremes predicted with climate change may increase crop yield variability. This variability may be reduced by increasing crop rotational diversity, but this proposition has not been systematically assessed in North America. Agricultural scientists across North America including ARS researchers in Lincoln, Nebraska, showed that crop rotational diversity increases corn yield across the United States by an average of 30% while yield losses under unfavorable weather conditions such as drought were reduced by 14 to 90%. Rotation diversification also increased corn yields over time and under better growing conditions. More diversified cropping systems would help reduce risk from increasingly stressful weather
Review Publications
Amorim, H.C., Ashworth, A.J., Wienhold, B.J., Savin, M.C., Allen, F.L., Saxton, A.M., Owens, P.R., Curi, N. 2020. Soil quality indices based on long-term conservation cropping systems management. Agrosystems, Geosciences & Environment. 3(1). Article e20036. https://doi.org/10.1002/agg2.20036.
Schmer, M.R., Jin, V.L., Wienhold, B.J., Becker, S.M., Varvel, G.E. 2020. Long-term rotation diversity and nitrogen effects on soil organic carbon and nitrogen stocks. Agrosystems, Geosciences & Environment. 3(1):e20055. https://doi.org/10.1002/agg2.20055.
Amorim, H., Ashworth, A.J., Moore Jr, P.A., Wienhold, B.J., Savin, M.C., Owens, P.R., Jagadamma, S., Carvalho, T.S., Sutie, X. 2020. Soil quality indices following long-term conservation pasture management practices. Agriculture, Ecosystems and Environment. 301. Article 107060. https://doi.org/10.1016/j.agee.2020.107060.
Jin, V.L., Schmer, M.R., Stewart, C.E., Mitchell, R., Williams, C.O., Wienhold, B.J., Varvel, G.E., Follett, R.F., Vogel, K.P., Kimble, J. 2019. Management controls the net greenhouse gas outcomes of growing bioenergy feedstocks on marginally productive croplands. Science Advances. 5(12):1-6. https://doi.org/10.1126/sciadv.aav9318.
Panday, D., Mikha, M.M., Collins, H.P., Jin, V.L., Kaiser, M., Cooper, J., Malakar, A., Maharjan, B. 2020. Optimum rates of surface-applied coal char decreased soil ammonia volatilization loss. Journal of Environmental Quality. 49:256-267. https://doi.org/10.1002/jeq2.20023.
Bowles, T.M., Mooshammer, M., Socolar, Y., Calderon, F.J., Cavigelli, M.A., Culman, S.W., Deen, W., Drury, C.F., Garcia Y Garcia, A., Gaudin, A., Harkcom, W., Lehman, R.M., Osborne, S.L., Robertson, G., Salerno, J., Schmer, M.R., Strock, J., Grandy, A. 2020. Long-term evidence shows crop rotation diversification increases agricultural resilience to adverse climate conditions in North America. One Earth. 2:284-293.
Schmer, M.R., Jin, V.L., Ferguson, R.B., Wienhold, B.J. 2020. Irrigation, carbon amelioration, nitrogen, and stover removal effects on continuous corn.. Agronomy Journal. 112:2506-2518. https://doi.org/10.1002/agj2.20192.
