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Animal manures are commonly used to enhance soil fertility, but there are growing concerns over the impact of this practice on the development and dissemination of antibiotic resistance. The aim of this field study was to determine the effect of annual dairy manure applications on the occurrence and abundance of antibiotic resistance genes (ARGs) in an agricultural soil during four years of crop production. Treatments included (i) control (no fertilizer or manure), (ii) inorganic fertilizer and (iii) dairy manure at three application rates. Quantitative PCR was used to determine absolute (per g dry soil) and relative (per 16S rRNA gene) abundances of ARGs in DNA extracted from soils. Six ARGs and one class 1 integron were targeted. This study found that (i) manure application increases ARG abundances above background soil levels; (ii) the higher the manure application rate, the higher the ARG abundance in soil; (iii) the amount of manure applied is more important than reoccurring annual applications of the same amount of manure; (iv) absolute abundance and occurrence of ARGs decreases with increasing soil depth, but relative abundances remained constant. This study demonstrated that dairy manure applications to soil significantly increase the abundance of clinically relevant ARGs when compared to control and inorganic fertilized plots.

This long‐term study was established to increase knowledge of greenhouse gas (GHG) emissions from irrigated cropping systems utilizing dairy manure solids and compost in semiarid southern Idaho. The objective of this field study was to determine the effect of synthetic N fertilizer (urea or SuperU [enhanced‐efficiency synthetic fertilizer]), composted dairy manure, dairy manure (fall or spring applied), and a control (no fertilizer or manure) on nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) emissions over the growing season. The fertilizer and manure treatments were not applied to alfalfa (Medicago sativa L.) (2017) but were applied to corn (Zea mays L.) (2018; except SuperU) and barley (Hordeum vulgare L.) (2019). Cumulative N2O losses over the 3 yr ranged from 2.8 to 5.2 kg N2O‐N ha–1, with the fall and spring manure emitting the greatest amounts of N2O. Emission factors indicated that up to 0.79% of the total N applied was lost as N2O‐N during the growing seasons. Cumulative losses of CO2 and CH4 across the rotation were on average 12,170 kg CO2–C ha–1 and –0.77 kg CH4–C ha–1, respectively, with no significant differences among the treatments. Major N2O pulses were associated with early‐season irrigation events and incorporation of fertilizer and manure, but overall fluxes tended to be the greatest when soil temperatures were higher. Dairy manure and compost applications were also found to cause rapid and significant increases in soil organic carbon (SOC) in the top 30 cm of soil under corn and barley. Despite the fact that manure does cause elevated soil N2O emissions, it should be considered as an alternative to synthetic fertilizer use due to its ability to increase SOC and potentially help reduce the global warming potential.

Concentrated animal feeding operations emit trace gases such as ammonia (NH3), methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). The implementation of air quality regulations in livestock‐producing states increases the need for accurate on‐farm determination of emission rates. The objective of this study was to determine the emission rates of NH3, CH4, CO2, and N2O from three source areas (open lots, wastewater pond, compost) on a commercial dairy located in southern Idaho. Gas concentrations and wind statistics were measured each month and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open lots were 0.13 kg NH3, 0.49 kg CH4, 28.1 kg CO2, and 0.01 kg N2O. Average emissions from the wastewater pond (g m−2 d−1) were 2.0 g NH3, 103 g CH4, 637 g CO2, and 0.49 g N2O. Average emissions from the compost facility (g m−2 d−1) were 1.6 g NH3, 13.5 g CH4, 516 g CO2, and 0.90 g N2O. The combined emissions of NH3, CH4, CO2, and N2O from the lots, wastewater pond and compost averaged 0.15, 1.4, 30.0, and 0.02 kg cow−1 d−1, respectively. The open lot areas generated the greatest emissions of NH3, CO2, and N2O, contributing 78, 80, and 57%, respectively, to total farm emissions. Methane emissions were greatest from the lots in the spring (74% of total), after which the wastewater pond became the largest source of emissions (55% of total) for the remainder of the year. Data from this study can be used to develop trace gas emissions factors from open‐lot dairies in southern Idaho and potentially other open‐lot production systems in similar climatic regions.

Improving our understanding of antibiotic resistance in soils is important for the protection of human, animal and ecological health. In south-central Idaho, antibiotic resistance genes (ARGs) [blaCTX-M-1, erm(B), sul1, tet(B), tet(M) and tet(X)] and a class 1 integron-integrase gene (intI1) were quantified in agricultural and non-agricultural soils (96 total sites) under various land use practices (cropland, forestland, inactive cropland, pastureland, rangeland, recreational, residential). We hypothesized that gene occurrence and abundance would be greater in intensively managed agricultural soils. The ARGs (except blaCTX-M-1) and intI1 gene were detected in many of the soils (15 to 58 out of 96 samples), with sul1 and intI1 being detected the most frequently (60% of samples). All of the genes were detected more frequently in the cropland soils (46 sites) and at statistically greater relative abundances (per 16S rRNA gene) than in soils from the other land use categories. When the cropland gene data was separated by sites that had received dairy manure, dairy wastewater, and/or biosolids (27 sites), it was revealed that the genes [except tet(B)] were found at statistically greater abundances (7- to 22-fold higher on average) than in soils that were not treated. The results from this study provide convincing evidence that manure/biosolids use in Idaho cropland soils increases the expansion of antibiotic resistance-related determinants.

Understanding the storage requirements of emerging potato cultivars is paramount for effective storage management. Thus, the objective of this study was to quantify the respiration rates of the standard Russet Burbank, and the new cultivars Ivory Russet, Dakota Russet, and Rainier Russet potatoes to understand the relationship between respiration rate and quality parameters during storage. Tubers were cured at 12.8 °C and 95% relative humidity (RH) for 14 days before gradually transitioning to 5.5, 7.2, or 8.9 °C (95% RH). Lower respiration rates were observed at 5.5 °C, with comparable rates at 7.2–8.9 °C. Dakota Russet had lower respiration rates (0.95 mg CO2 kg−1 h−1) while Rainier Russet the highest (1.29 mg CO2 kg−1 h−1). Sucrose content was negatively affected by respiration of Ivory Russet, Rainier Russet, and Russet Burbank, glucose content was affected by all cultivars, though. Fry color (Photovolt reflectance) was positively correlated to the respiration rates of all cultivars. The respiration rates had low correlations with all quality parameters.

Understanding the long‐term effects of manure applications on the soil microbial component in semiarid climates will be key to sustain essential processes that affect their productivity and soil health. In this paper, soil health indicators encompassed both selected chemical and biological indicators. From 2004 to 2009, solid dairy manure treatments were applied to plots at cumulative rates of 0, 134, and 237 dry Mg ha−1 (34–56 dry Mg ha−1 year−1) in a randomized complete block with three replicates. Soil samples were taken from each manure rate in the spring of 2020 at 0–15 and 15–30 cm. Eleven years after manure applications ceased, many of the soil chemical and biological indicators were different between the manure and control treatments. In general, soil organic carbon and biological indicators were significantly greater in the 134 and 237 Mg ha−1 treatments as compared to the 0 Mg ha−1 treatment. Core Ideas Dairy manure has long‐term effects on soil health indicators in southern Idaho semiarid irrigated soils. Dairy manure last applied 11 years prior to soil sampling increased many of the soil health indicators. Soil biological indicators can be effectively utilized to understand the legacy effects of manure.

Concentrated dairy operations emit trace gases such as ammonia (NH3), methane (CH4), and nitrous oxide (N2O) to the atmosphere. The implementation of air quality regulations in livestock‐producing states increases the need for accurate on‐farm determination of emission rates. Our objective was to determine the emission rates of NH3, CH4, and N2O from the open‐freestall and wastewater pond source areas on a commercial dairy in southern Idaho using a flush system with anaerobic digestion. Gas concentrations and wind statistics were measured and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open‐freestall source area were 0.08 kg NH3, 0.41 kg CH4, and 0.02 kg N2O. Average emissions from the wastewater ponds (g m−2 d−1) were 6.8 NH3, 22 CH4, and 0.2 N2O. The combined emissions on a per cow per day basis from the open‐freestall and wastewater pond areas averaged 0.20 kg NH3 and 0.75 kg CH4. Combined N2O emissions were not calculated due to limited available data. The wastewater ponds were the greatest source of total farm NH3 emissions (67%) in spring and summer. The emissions of CH4 were approximately equal from the two source areas in spring and summer. During the late fall and winter months, the open‐freestall area constituted the greatest source area of NH3 and CH4 emissions. Data from this study can be used to develop trace gas emissions factors from open‐freestall dairies in southern Idaho and other open‐freestall production systems in similar climatic regions.

Ammonia, greenhouse gases, and particulate emissions from livestock operations can potentially affect air quality at local, regional, and even global scales. These pollutants, many of which are generated through various anthropogenic activities, are being increasingly scrutinized by regulatory authorities. Regulation of emissions from livestock production systems will ultimately increase on farm costs, which will then be passed onto consumers. Therefore, it is essential that scientifically based emission factors are developed for on‐farm emissions of air quality constituents to improve inventories and assign appropriate reduction targets. To generate a larger database of on‐farm emissions, the USDA–ARS created the workgroup Livestock GRACEnet (Greenhouse gas Reduction through Agricultural Carbon Enhancement Network). This introduction for the special section of papers highlights some of the research presently being conducted by members of Livestock GRACEnet with the intent of drawing attention to critical information gaps, such as (i) improving emissions measurements; (ii) developing emissions factors; (iii) developing and validating tools for estimating emissions; and (iv) mitigating emissions. We also provide a synthesis of the literature with respect to key research areas related to livestock emissions, including feeding strategies, animal housing, manure management, and manure land application, and discuss future research priorities and directions.

Insufficient characterization of soil organic carbon (SOC) dynamics in semi-arid climates contributes uncertainty to SOC sequestration estimates. This study estimated changes in SOC (0–30 cm depth) due to variations in manure management, tillage regime, winter cover crop, and crop rotation in southern Idaho (USA). Empirical data were used to drive the Denitrification Decomposition (DNDC) model in a “default” and calibrated capacity and forecast SOC levels until 2050. Empirical data indicates: (i) no effect (p = 0.51) of winter triticale on SOC after 3 years; (ii) SOC accumulation (0.6 ± 0.5 Mg ha–1 year–1) under a rotation of corn-barley-alfalfax3 and no change (p = 0.905) in a rotation of wheat-potato-barley-sugarbeet; (iii) manure applied annually at rate 1X is not significantly different (p = 0.75) from biennial application at rate 2X; and (iv) no significant effect of manure application timing (p = 0.41, fall vs. spring). The DNDC model simulated empirical SOC and biomass C measurements adequately in a default capacity, yet specific issues were encountered. By 2050, model forecasting suggested: (i) triticale cover resulted in SOC accrual (0.05–0.27 Mg ha–1 year–1); (ii) when manure is applied, conventional tillage regimes are favored; and (iii) manure applied treatments accrue SOC suggesting a quadratic relationship (all R2 > 0.85 and all p < 0.0001), yet saturation behavior was not realized when extending the simulation to 2100. It is possible that under very large C inputs that C sequestration is favored by DNDC which may influence “NetZero” C initiatives.

As of 2007, of the 2,000 United States foundries, 93% produce ferrous or aluminum castings, generating 9.4 million tons of non-hazardous spent foundry sand (SFS) annually. Only 28% of the SFS is beneficially used. The U.S. EPA Resource Conservation Challenge identifies SFS as a priority material for beneficial use, with soil blending as a potential reuse option. The objectives of this work were to measure: (1) select chemical and physical properties important to soil quality and function and (2) total and soluble elemental content of 39 SFSs, in order to evaluate SFS suitability as a component in manufactured soils. Total elemental concentration of the SFS was lower than natural background soil levels for most elements analyzed, suggesting limited to no contamination of the virgin sand during metal casting. Pore water elemental concentrations were generally below detection. However, both total and soluble elemental content indicate a potential contribution of plant nutrients. Lettuce (Lactuca sativa) planted in SFS mixtures had a median germination rate of 96.9% relative to the control. Blending SFS at varying ratios with other materials will allow “tailoring” of a manufactured soil's chemical and physical properties to meet specific growing needs. The SFS organic carbon, clay, and plant nutrient content are benefits of SFS that may make them good candidates as manufactured soil components.