Location: Agroecosystem Management Research
2019 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 that fall under NP216. Under Objective 1A, over 1, 200 soil samples have been processed, checked for quality control, and have been summarized. Initial data will be presented in FY20. Data suggests that crop rotation diversity increases soil organic carbon, but long-term nitrogen fertilizer levels have modest effects on soil carbon changes. For Objective 1B, soil greenhouse gas data have been collected using static chamber methodology and data have been summarized. 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. A presentation on initial data will be presented in FY20. For Objective 2A, substantial progress has been made with soil samples completed and archived. Soil samples have been sent to research colleagues for soil biological property analysis to better understand regional impacts from current integrated-crop livestock management practices. Soil greenhouse gas emissions have been conducted in perennial and annual systems (Objective 2B). For Objective 3A, soil matric potential water sensors have been installed in switchgrass and corn treatments and previous data have been summarized. A presentation on switchgrass water use was presented in FY19. Under Objective 3B, substantial progress has been made with 8 years of nitrogen use efficiency data have been summarized and a manuscript has been submitted. In addition, data have been presented to local farmers on proper corn stover management. Progress has been made for Objective 4. Hosted the annual Long-term Agroecosystem Research Network meeting. Baseline soil data have been analyzed and checked for quality control (Objective 4A). Existing business-as-usual experimental sites are fully instrumented to measure carbon dioxide flux, weather data, and collect phenocam data (Objective 4B).
Accomplishments
1. Determining the value of grazed corn residue for crop and cattle producers. Corn residue grazing, primarily by beef cattle, provides a simple and economical practice to integrate crops and livestock in the central United States. However, the overall economic value of this practice is unknown. ARS scientists in Lincoln, Nebraska, in collaboration with university colleagues determined that grazed corn residue annually returned $95 million to crop producers in Kansas, Nebraska, South Dakota, and North Dakota. The annual gross value for grazing corn residue for cattle producers was $191 million in these states. Although challenges exist to expand corn residue grazing, opportunities are available in the central United States to further increase net returns by increasing corn residue grazing as a cost-efficient winter forage.
2. Determining how residue removal affects soil properties. Crop residue removal in high-production systems can supply feedstocks for both livestock and bioenergy. Management practices that can ameliorate potential negative effects on soil properties from crop residue removal is needed. ARS researchers in Ft. Collins, Colorado, and Lincoln, Nebraska, evaluated long-term sites in the central Plains to determine how soil organic carbon and soil microbial biomass is affected by crop residue removal. Crop residue removal decreased soil organic carbon and soil aggregation with the majority of declines occurring near the soil surface. Crop residue removal did not change soil microbial biomass or soil microbial communities. Results suggest that conservation tillage practices alone are inadequate to maintaining important soil properties for the central Plains. The use of cover crops or manure may be required in addition to conservation practices if crop residue removal occurs.
Review Publications
Reichmann, L.G., Collins, H.P., Jin, V.L., Johnson, M.V., Kiniry, J.R., Mitchell, R., Polley, H.W., Fay, P.A. 2018. Inter-annual precipitation variability decreases switchgrass productivity from arid to mesic environments. BioEnergy Research. 11(3):614-622. https://doi.org/10.1007/s12155-018-9922-3.
Karlen, D.L., Schmer, M.R., Kaffka, S.R., Clay, D.E., Wang, M.Q., Horwath, W.R., Kendall, A.M., Keller, A., Pieper, B., Unnasch, S., Darlington, T., Vocasek, F., Chute, A.G. 2018. Unraveling crop residue harvest effects on soil organic carbon. Agronomy Journal. 111:93-98. https://doi.org/10.2134/agronj2018.03.0207.
Dien, B.S., Mitchell, R.B., Bowman, M.J., Jin, V.L., Quarterman, J.C., Schmer, M.R., Singh, V., Slininger, P.J. 2018. Bioconversion of pelletized big bluestem, switchgrass, and low-diversity grass mixtures into sugars and bioethanol. Frontiers in Energy Research. 6:129. https://doi.org/10.3389/fenrg.2018.00129.
Lisboa, I.P., Cherubin, M.R., Satiro, L.S., Neto, M.S., Lima, R., Wienhold, B.J., Schmer, M.R., Jin, V.L., Cerri, C.C., Cerri, C.E. 2019. Applying soil quality management assessment framework (SMAF) on short-term sugarcane straw removal in Brazil. Industrial Crops and Products. 129:175-184. https://doi.org/10.1016/j.indcrop.2018.12.004.
Stewart, C.E., Roosendaal, D.L., Sindelar, A.J., Jin, V.L., Schmer, M.R. 2019. Does no-tillage mitigate stover removal in irrigated continuous corn? A multi-location assessment. Soil Science Society of America Journal. 83(3):733-742. https://doi.org/10.2136/sssaj2018.09.0352.
