Location: Northwest Irrigation and Soils Research
2021 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
This is the final annual report for 2054-12000-011-00D, Improving Management Practices for Irrigated Western Cropping and Dairy Systems to Contribute to Sustainability and Improve Air Quality, which will be replaced by 2054-12000-011-00D, Developing Resilient Irrigated Cropping Systems in Concentrated Dairy Production Areas of the Semi-arid West. For additional information, see the new project report.
Four studies conducted under Objective 1 determined the effects of manure and nitrogen (N) fertilizer on crop yields, soil properties, nutrient budgets, and greenhouse gas (GHG) emissions with various crop rotations. Three studies showed that dairy manure is an excellent plant nutrient source, increasing crop yield and soil organic carbon. High application rates, however, lead to excess soil nutrients and some negative impacts on crop quality for potato, barley and sugar beet. For example, sugar beet root yield increased with manure application rate but sucrose content in the roots was lower for the highest manure application rates. Dairy manure also increased forage production in a corn silage-winter triticale rotation. Triticale forage yield was five to six times greater in plots that received manure compared to plots that were only fertilized based on corn silage production. Spring soil nitrate concentrations were also lower in triticale plots indicating that the winter crop stabilized soil nitrate and may reduce nitrate losses. Over an eight-year period, crops removed greater N and phosphorus (P) from manure treatments compared to commercial fertilizer. Although plant removal was greater, the overall N and P balances were positive, meaning that large amounts of N and P were left in the soil, where it could be lost to runoff or leaching.
In addition to measuring soil nutrients and crop production, soil gas emissions were measured in two of the three studies. Nitrous oxide emissions were two to three times greater from manure treatments than urea fertilizer. Using urea fertilizer with enzyme inhibitors did not reduce nitrous oxide emissions. Nitrous oxide emission pulses were associated with irrigation events as well as fertilizer and manure incorporation. Ultimately, less than one percent of the applied nitrogen was lost to the atmosphere as nitrous oxide. These data have been included in an international database to improve emission factors for cropping systems and used to estimate the carbon footprint of regional dairy production.
In study four, corn silage response to N fertilizer application was measured in nine field trials in non-manured soil. Two trials had yield responses to N and seven did not. These data suggest that using preplant soil tests is not sufficient to guide N fertilizer needs. Additional N application research demonstrated that a static N range strategy was superior to the historic yield-based approach.
In support of Objective 2, field studies were investigated the impact of agricultural production on the prevalence and abundance of antibiotics, antibiotic resistance genes, and antibiotic resistant bacteria. In a south-central Idaho watershed, irrigation return flows contained trace quantities of antibiotics that are used in humans and animals. Monensin, which is only used in livestock, was detected at the highest rate. Some antibiotics were also detected in an irrigation canal indicating that antibiotics in irrigation return flows could originate in the river upstream from the watershed. Irrigation return flows also had elevated levels of antibiotic resistance genes. While antibiotic resistance genes are found naturally in the environment, an elevated presence could result from contamination by human or animal feces. In addition, a wide variety of antibiotic resistance patterns were found among fecal indicator bacteria in the watershed, suggesting that resistance genes were horizontally transferred among microbial populations in the aquatic environment. Bacterial isolates were found to be resistant to up to 10 antibiotics. Irrigation return flows provide a potential environment for the development of antibiotic resistance, as well as a transport mechanism for resistance genes and multidrug resistant bacteria out of agroecosystems.
In a long-term dairy manure application study, a direct correlation was found between the manure application rate and antibiotic resistance gene level. When dairy wastewater was applied to soil, there was also an increase in the gene levels. Gene level increases mainly resulted from adding extracellular and intracellular genes found in manure, not a result of enrichment of antibiotic resistant bacteria. A laboratory microcosm study showed that extracellular and intracellular antibiotic resistance gene levels were not readily affected by changes in soil moisture and temperature, thus they can persist for many weeks. A survey of selected antibiotic resistance genes in 96 agricultural and non-agricultural soils in south-central Idaho found that gene levels were significantly greater in soils that had received dairy manure, dairy wastewater or biosolids. These studies provide evidence that manure and biosolid use in cropland soils can increase the expansion of antibiotic resistance-related determinants.
In support of Objective 3, two large dairy farms in California and one pasture-based dairy in Idaho were monitored to determine sources and temporal variability of emissions. These data will improve dairy farm emission factors and guide development of mitigation strategies to reduce ammonia and GHG emissions. The California study evaluated open-path, vehicle and aircraft measurement methods and compared emission measurements with U.S. Environmental Protection Agency (USEPA) emissions estimates. Whole-facility methane estimates were similar among measurement techniques. No seasonality was detected for methane emissions from animal housing, but methane emissions from liquid manure storage were three to six times greater during the summer than during the winter. The findings confirm previous studies showing that methane emissions need to be measured throughout the year to estimate annual emissions. Open-path measurements for liquid manure storage emissions were similar to monthly USEPA estimates during the summer, but not during the winter measurement periods. However, the numerical difference was relatively small considering yearly emission estimates.
Average methane emissions from the lagoons in Idaho ranged from 22 to 517 kg/day with a general trend of greater emissions during the summer when temperatures were greater. Events such as pumping, rainfall, freezing or thawing, and wind significantly increased methane emissions irrespective of temperature. The USEPA method underestimated methane emissions by 48%. An alternative methodology using volatile solids degradation factor provided a more accurate estimate of annual emissions from the lagoon system and may be applicable for a range of dairy lagoon systems in the United States. Methane prediction models were developed using volatile solids, wind speed, air temperature and pH.
Average total ammonia emissions from the lagoons ranged from 5.4 to 85 kg/day. Emissions were generally greater during the summer when temperatures were greater. High wind events and lagoon agitation created temporary increases in ammonia emissions irrespective of temperature. Regression models were developed to predict ammonia emissions using total N, total ammonia N, wind speed, air temperature and pH. A process-based model (Integrated Farm System Model, IFSM) estimated values for N excretion and ammonia N loss from the lagoon within 5% of measured values. Data from dairy housing and manure management systems were used to validate and improve farm emission estimates in two whole farm dairy models: Dairy CropSys and IFSM.
Studies evaluating diet effects on enteric methane emissions and N excretion from lactating dairy cows showed that increasing dietary forage contents caused greater methane emission and manure N excretion. Cows receiving reduced crude protein diets had low manure N outputs and improved milk protein production efficiencies, regardless of dietary forage content.
An Ammonia Monitoring Network (AMoN) station was established as well as six additional stations to monitor ammonia concentrations throughout a six county agricultural area in southern Idaho. Agriculture has a large impact on ambient regional ammonia concentrations. There were seasonal concentration variations with the lowest concentrations found in the winter and the highest in the summer, particularly in areas with dairy production. Both temperature and wind speed were correlated with ammonia concentrations, with concentrations increasing with increasing temperature and decreasing with increasing wind speed. These data were utilized with the USEPA STAGE model to estimate regional ammonia concentrations and fluxes. Results suggest that ammonia deposition was minimal (less than 1 kg/ha per year) in areas not impacted by agriculture and higher deposition (approximately 10 kg/ha N per year) in agricultural areas with the greatest deposition in areas near concentrated dairy production (30-40 kg/ha N per year). The critical N loading rates for natural ecosystems in this region are approximately 2 kg/ha N per year, suggesting that N transport and deposition from agricultural activities in the region could negatively impact surrounding ecosystems.
Data from the regional network were used by scientists at the Jet Propulsion Laboratory to validate ammonia concentrations estimated from Crosstrack Infrared Sounder (CrIS) satellite observation. Results indicate that there was good temporal correlation, and at most sites the CrIS and ground ammonia concentrations were similar in warm months, but the CrIS concentrations biased low in cold months. The CrIS data was also biased low compared to ground data in areas with high concentrations of dairy cattle.
Accomplishments
1. Applying dairy manure increases soil carbon with corn silage production. The U.S. dairy industry set a goal to be carbon neutral by 2050. One option to offset greenhouse gas emissions from dairy farms is to store carbon during crop production. ARS researchers at Kimberly, Idaho, found that applying dairy manure consistently generated the largest increase in soil carbon storage. In continuous corn silage production, reducing tillage or including winter triticale that was harvested for forage did not increase soil carbon since nearly all above-ground biomass was harvested. Crop rotations including potato and sugar beet have variable impacts on carbon storage since harvest removes plant material from the soil. While enhancing soil carbon storage can offset carbon emissions, it is not likely to reliably offset all emissions from the greater dairy production system.
2. On-farm data improve ammonia and greenhouse gas emission estimates for dairy production. Ammonia and greenhouse gas emissions from dairy production are a concern for air quality, climate change and sensitive ecosystems. ARS researchers at Kimberly, Idaho, provided a comprehensive dataset of emissions from dairy production facilities, including emissions from specific areas within farms, to identify the magnitude and origin of emissions and potential mitigation strategies. These data were used to improve farm emission estimates from dairy farm models Dairy CropSys and Integrated Farm System Model (IFSM) and to demonstrate that U.S. Environmental Protection Agency (US EPA) inventory methodologies underestimate methane emissions on dairy farms. These data were included in the Global Research Alliance database (DATAMAN) to develop improved emissions factors as well as provided to the US EPA to improve ammonia emission methodologies for manure storages. These data are ensuring that realistic dairy farm greenhouse gas emission estimates are included in USDA and Intergovernmental Panel on Climate Change (IPCC) emission inventories.
Review Publications
Beltran, I., Van Der Weerden, T.J., Alfaro, M.A., Amon, B., De Klein, C.A., Grace, P., Hafner, S., Hassouna, M., Hutchings, N., Krol, D.J., Leytem, A.B., Noble, A., Salazar, F., Thorman, R.E., Velthof, G.L. 2021. DataMan: A global dataset of nitrous oxide and ammonia emission factors for excreta deposited by livestock and land-applied manure. Journal of Environmental Quality. https://doi.org/10.1002/jeq2.20186.
Bierer, A.M., Leytem, A.B., Dungan, R.S., Moore, A., Bjorneberg, D.L. 2021. Soil organic carbon dynamics in semi-arid irrigated cropping systems. Agronomy. 11(484):1-30. https://doi.org/10.3390/agronomy11030484.
Dungan, R.S., Leytem, A.B., Tarkalson, D.D. 2021. Greenhouse gas emissions from an irrigated cropping rotation with dairy manure utilization in a semiarid climate. Agronomy Journal. 113(2):1222-1237. https://doi.org/10.1002/agj2.20599.
Dungan, R.S., Bjorneberg, D.L. 2021. Antimicrobial resistance in escherichia coli and enterococcal isolates from irrigation return flows in a high-desert watershed. Frontiers in Microbiology. 12. Article 660697. https://doi.org/10.3389/fmicb.2021.660697.
Bierer, A., Leytem, A.B., Dungan, R.S., Rogers, C.W. 2020. Evaluation of a microplate spectrophotometer for soil organic carbon determination in south-central Idaho. Soil Science Society of America Journal. https://doi.org/10.1002/saj2.20165.
Leytem, A.B., Williams, P., Zuidema, S., Martinez, A., Chong, Y., Vincent, A., Vincent, A., Cronan, D., Kliskey, A., Wulfhorst, J., Alessa, L., Bjorneberg, D.L. 2021. Cycling phosphorus and nitrogen through cropping systems in an intensive dairy production region. Agronomy. 11(5):1005. https://doi.org/10.3390/agronomy11051005.
