Location: Northwest Irrigation and Soils Research
2020 Annual Report
Objectives
Objective 1: Assess organic and inorganic fertilizer forms and application methods as management options for reducing greenhouse gas emissions, increasing nutrient use efficiencies, and optimizing crop yields for irrigated western cropping systems.
Subobjective 1A: Identify effects of fertilizer source, timing and nitrification and urease inhibitors on GHG emissions, nutrient cycling, and field scale nutrient budgets.
Subobjective 1B: Identify effects of manure application rate and frequency on GHG emissions, nutrient cycling, and field scale nutrient budgets.
Subobjective 1C: Determine the efficacy of cover crops to reduce offsite transport of soil nutrients in a dairy forage crop rotation receiving manure.
Subobjective 1D: Evaluate N supply and timing effects on corn yields and nitrogen use.
Subobjective 1E: Determine the interacting effects of manure and fertilizer on soil N mineralization.
Subobjective 1F: Determine the effects of manure incorporation method and timing on the emissions of CO2 and N2O from moist soils subjected to diurnal freeze-thaw cycles.
Objective 2: Investigate the occurrence and transport of antibiotic drugs, antibiotic-resistance genes, and antibiotic-resistant bacteria in irrigated western cropping systems to provide baseline data needed to develop mitigation strategies.
Subobjective 2A: Monitor antibiotics in irrigation return waters to better understand their persistence in the environment and potential movement from areas under intensive dairy and crop production.
Subobjective 2B: Conduct an inter-laboratory validation of assays to screen selected antibiotic resistance determinants.
Subobjective 2C: Determine the influence of dairy manure and compost application rate, soil temperature, and soil moisture content on the occurrence of antibiotic resistant bacteria and antibiotic resistance genes in soil.
Subobjective 2D: Evaluate the effect of annual dairy manure applications, as well as crop rotation, on the distribution of antibiotic resistance genes in the soil profile.
Subobjective 2E: Determine the prevalence of antibiotic resistant indicator bacteria and antibiotic resistance genes in plots irrigated with diluted dairy wastewater with and without added copper sulfate.
Objective 3: Improve measurement and prediction of ammonia and GHG emissions and transport from western dairy systems to improve GHG inventories and evaluate the mitigation potential of management practices.
Subobjective 3A: Improve emission factors for NH3 and GHG emissions from western dairy production systems and improve/validate equations and process based models for estimating emissions.
Subobjective 3B: Improve understanding of impacts of NH3 losses on regional air quality.
Approach
Sustainable crop and dairy production requires efficient nutrient use. Modern dairy farms produce more milk with fewer inputs per unit of milk than farms in the past. Crop yields continue to increase with improved genetics and management. At the same time, nutrient losses to the environment can negatively impact air and water quality. This is especially a concern when concentration of animal production increases the amount of nutrients brought into an area. This project addresses environmental and agronomic issues associated with irrigated crop and dairy production. Specifically, the research seeks to increase crop nutrient use efficiency, minimize nutrient losses and greenhouse gas (GHG) emissions, and reduce occurrence and transport of antibiotics and antibiotic resistance bacteria. The long-term goal of this project is to develop tools to predict nutrient budgets, antibiotic resistance and emissions in the dairy farm-crop production system.
Project objectives will be achieved through several ongoing and new studies conducted at different scales to improve our understanding and management of nutrients, ammonia and GHG emissions, and antibiotic resistant bacteria and genes in dairy and crop production. Research for Objective 1 encompasses six studies evaluating effects of commercial fertilizer with and without nitrification and urease inhibitors, dairy manure, dairy manure compost, and cover crops on gas emissions, soil nutrient cycling, and crop nutrient uptake. Objective 2 contains five studies to evaluate the existence, fate and transport of antibiotics and antibiotic resistant bacteria and genes in soils and surface water. Objective 3 will utilize existing and new data to improve and validate established farm system models that predict nutrient cycling and gas emissions.
Progress Report
Three long-term studies continued and two short-term studies were completed in support of Objective 1. The seventh year of the study assessing the effects of: 1) fertilizer source and timing, and 2) nitrification and urease inhibitors on greenhouse gas emissions, nutrient cycling, and field scale nutrient budgets was completed. The seventh year of an eight-year study evaluating the impacts of manure application rate and frequency on greenhouse gas emissions, nutrient cycling, and field scale nutrient budgets was completed. Soil and plant sampling continued as planned, including nitrogen mineralization measurements. The last year for potatoes in the crop rotation was 2018. Two manuscripts have been prepared examining the effects of manure application on potato nutrient uptake, yield and potato quality. The fourth year of a study evaluating the impacts of manure, tillage, and cover crop on nutrient cycling and losses was completed. Soil and plant sampling continued as planned with the addition of soil nitrogen mineralization measurements. Data from these three studies are being used for a larger scale analysis of manure application and cropping system effects on soil organic matter accumulation and storage. These data are also being used to determine the potential for regional dairy production to have a “net zero” carbon balance.
The field portion of the study to evaluate nitrogen supply effects on corn production was completed. Data analysis are complete and a manuscript is being prepared. Data analysis indicates that determining nitrogen fertilizer application rates based on yield goals and inorganic nitrogen in spring soil samples is not accurate. Further research needs to be conducted to determine better methodologies to guide nitrogen fertilizer recommendations.
A study to determine the interacting effects of manure and fertilizer on soil nitrogen (N) mineralization was completed. Sample collection and chemical analysis has been completed and the data are being organized for statistical analysis.
Two studies conducted in support of Objective 2 were completed ahead of schedule and reported in the 2019 annual report. One study evaluated the effect of annual dairy manure applications, as well as crop rotation, on the distribution of antibiotic resistance genes in the soil profile. A second study determined the prevalence of antibiotic resistant indicator bacteria and antibiotic resistance genes in plots irrigated with diluted dairy wastewater with and without added copper sulfate.
In support of Objective 3, studies continued that are improving: 1) ammonia and greenhouse gas emission factors for western dairy production systems, and 2) equations and process-based models for estimating dairy farm emissions. A new field study was initiated to monitor ammonia and greenhouse gas emissions from a local organic dairy. In addition, the emissions database developed at Kimberly, Idaho, including five dairy farms, six additional dairy lagoons, and two long-term field studies, was added to the Global Research Alliance database DATAman. This database is being used to improve global emission factors for ammonia and greenhouse gasses. Ammonia emission data were also contributed to an Aarhus University project to improve ammonia emissions estimations for lagoons. Work also continued with the United States Environmental Protection Agency (USEPA) to develop reasonable ammonia emission factors from livestock operations in the United States.
An ammonia monitoring network was continued in southern Idaho to improve understanding of ammonia impacts on regional air quality. This network includes one station that is part of the national ammonia monitoring network (AMoN ). A cooperative project with USEPA was started to estimate ammonia transport and deposition downwind from a dairy as well as regionally throughout southern Idaho. In cooperation with Colorado State University, the effects of ammonia emissions on air quality parameters associated with human health risks were analyzed.
Accomplishments
1. Manure and wastewater applications increase the abundance of antibiotic-resistance-related elements in soil. Antibiotic resistance in bacteria threaten human and animal health. Livestock manure and wastewaters are commonly applied to agricultural soils to improve soil fertility; however, these organic fertilizers contain antibiotic resistance genes and antibiotic resistant bacteria. ARS researchers in Kimberly, Idaho, found that short- and long-term utilization of dairy manure (solids or wastewater) in irrigated agricultural soils increased the abundance of clinically relevant antibiotic resistance genes when compared to unfertilized and synthetically fertilized plots. Because manured fields are a reservoir of antibiotic-resistance-related components, those elements could be transported to waterbodies by field runoff events. This information is useful to the scientific community and risk assessors who are trying to understand and mitigate environmental risks associated with livestock manure use in agriculture.
Review Publications
Leytem, A.B., Rogers, C.W., Tarkalson, D.D., Dungan, R.S., Haney, R.L., Moore, A.D. 2020. Comparison of nutrient management recommendations and soil health indicators in southern Idaho. Agrosystems, Geosciences & Environment. 3(1):e20033. https://doi.org/10.1002/agg2.20033.
Rogers, C.W., Dari, B., Schroeder, K.L. 2019. Comparison of soil-test extractants for potassium, calcium, magnesium, sulfur, and micronutrients in Idaho soils. Agrosystems, Geosciences & Environment. 2(1):1-9. https://doi.org/10.2134/age2019.08.0067.
Rogers, C.W., Pristupa, S., Dari, B. 2019. Soil carbonate analysis using the solvita compost maturity gel system. Agricultural and Environmental Letters. 4(1):1-4. https://doi.org/10.2134/ael2019.10.0044.
Dungan, R.S., Bjorneberg, D.L. 2020. Antibiotic resistance genes, class 1 integrons, and IncP-1/IncQ-1 plasmids in irrigation return flows. Environmental Pollution. 257:1-8. https://doi.org/10.1016/j.envpol.2019.113568.
Dungan, R.S., McKinney, C.W. 2020. Influence of environmental conditions on extracellular and intracellular antibiotic resistance genes in manure-amended soil: A microcosm study. Soil Science Society of America Journal. 84(3):747-759. https://doi.org/10.1002/saj2.20049.
Sharpley, A., Helmers, M., Kleinman, P.J., King, K.W., Leytem, A.B., Nelson, N. 2019. Managing crop nutrients to achieve water quality goals. Journal of Soil and Water Conservation. 74(5):91A-101A. https://doi.org/10.2489/jswc.74.5.91A.
Loomis, G., Dari, B., Rogers, C.W., Sihi, D. 2020. Evaluation of residue management practices on barley residue decomposition. PLoS One. 15(5):e0232896. https://doi.org/10.1371/journal.pone.0232896.
