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Occurrence and abundance of antibiotic resistance genes in agricultural soil receiving dairy manure
Get PDFAnimal 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 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 under crop production. The experimental design was a randomized complete block with four replications, which included the following treatments: i) control (no fertilizer); ii) inorganic fertilizer; and iii) stockpiled dairy manure. Inorganic fertilizer was applied in the spring, while dairy manure was applied in the fall of 2012–2015 at 17.2, 34.5, and 52.0 Mg (dry wt.)/ha. Soil samples were collected in the spring (pre-plant) and fall (post-harvest) to a depth of 120 cm. DNA extracted from the soils was used in a quantitative real-time PCR reaction to determine absolute abundances (per g dry soil) and relative abundances (per 16S rRNA gene copies) of ARGs. The ARGs targeted were blaCTX-M-1, erm(B), sul1, tet(A), tet(W), and tet(X) and a class 1 integron-integrase gene (intI1), but only sul1, tet(W), tet(X), and intI1 were detected in enough samples to run statistics and draw conclusions. 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; and v) ARGs correlated with each other and a number of soil chemical parameters, but not with soil moisture or 16S rRNA gene. Overall, this study demonstrated that dairy manure applications significantly increase the abundance of clinically relevant ARGs when compared to soil that received inorganic fertilizer or no fertilizer/manure
Is static nitrogen management in northwestern U.S. sugarbeet production appropriate?
Get PDFNitrogen (N) management is important in sugarbeet production. Evaluation of historic data suggest that static N management (fixed N supply independent of yields) may have advantages compared to yield goal based N management in the Northwest U.S. From early 1970’s to 2011, the amount of N supply to maximize yields in research studies was within a narrow N supply range of 179 to 204 kg N/ha. Recommended N supplies have not increased as yields increased. Proposed static N recommendations aim to supply spring total available N supply (soil NO3-N and NH4-N to a depth of 0.9 m [3 ft] + fertilizer N) of less than 202 kg N/ha (180 lbs N/a) for heavier texture soils (sandy loams to clays) and less than 224 kg N/ha (200 lbs N/a) for course texture (loamy sands to sands) or shallow soils. These static supply recommendations represent maximum N supplies
Effects of dairy manure storage conditions on the survival of E. coli O157:H7 and listeria
Get PDFDairy manure is regularly applied to crop fields as a solid or liquid to improve the soil nutrient status. However, pathogens may survive during manure storage and enter the environment during application. In this study, three storage practices were evaluated to understand the survival patterns of E.coli O157:H7 and Listeria spp. in dairy manure using a culture-based approach. To replicate common farm manure storage techniques, solid manure was stacked as piles with periodic turning or as static piles without turning, while liquid manure (feces, urine, and water) was stored as a slurry in small tanks to simulate lagoon conditions. The E. coli and Listeria levels in the manure samples were determined for 29 weeks. Results showed that there was an initial reduction in bacteria levels in the first month; however, both E. coli and Listeria managed to survive in the solid manure piles for the full study period. In slurry samples, E.coli was not detected after 14 weeks, but Listeria survived until the end of the experiment at relatively lower levels compared to the solid manure piles. Ambient weather and pile size were identified as the main reasons for bacteria survival during the course of the experiment. The outcome of this study is important in terms of understanding pathogen survival in manure piles and slurries prior to their application to crop fields
Influence of Beet necrotic yellow vein virus and freezing temperatures on sugar beet roots in storage
Get PDFRhizomania caused by Beet necrotic yellow vein virus (BNYVV) is a yield limiting sugar beet disease that was observed to influence root resistance to freezing in storage. Thus, studies were conducted to gain a better understanding of the influence BNYVV and freezing on sugar beet roots to improve pile management decisions. Roots from five commercial sugar beet cultivars (one susceptible and four resistant to BNYVV) were produced in fields under high and trace levels of rhizomania pressure and subjected to storage using five temperature regimes ranging from 0 to -4.4 C for 24 hours. After cold treatment, eight-root samples were stored in a commercial indoor storage building (set point 1.1 C) for 50 days in 2014 and 57 days in 2015. Internal root temperature, frozen and discolored tissue, and moisture and sucrose loss were evaluated. The air temperature at 0, -1.1, and -2.2 C matched internal root temperature, but internal root remained near -2.2°C when air temperature was dropped to -3.3 and -4.4 C. In a susceptible cultivar produced under high rhizomania pressure, the percentage of frozen tissue increased (P < 0.0001) from an average of 0 to 7% at 0, -1.1, and -2.2 C up to 16 to 63% at -3.3 C and 63 to 90% at -4.4 C depending on year. Roots from the susceptible cultivar produced under low rhizomania pressure and those from the resistant cultivars from both fields only had elevated (P < 0.05) frozen tissue at -4.4 C in 15 of 18 cultivar-year combinations. Frozen tissue was related to discolored tissue (r^2 = 0.91), weight loss (r^2 = 0.12 to 0.28) and sucrose reduction (r^2 = 0.69 to 0.74). Thus, BNYVV will not only lead to yield and sucrose loss in susceptible sugar beet cultivars, but also more frozen root tissue as temperatures drop below -2.2 C. Based on these observations, the air used to cool roots in nonfrozen sugar beet piles throughout the winter should not drop below -2.2 C to maximize sucrose retention
Rhizomania and storage rot resistance in USDA-ARS plant introduction lines evaluated in Idaho, 2017
Get PDFRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, 30 USDA-ARS Beta vulgaris Plant Introduction (PI) Lines and four check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2017 growing season in a randomized complete block design with 6 replications. At harvest on 10 October 2017, roots were dug and evaluated for rhizomania symptoms and also placed in an indoor commercial sugar beet storage building. After 133 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development in the field was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible check had 97% foliar symptoms and a high root disease severity rating. The three resistant checks had 0 to 6% foliar symptoms and the lowest root ratings. Based on root ratings, all PI Line entries were more susceptible than the resistant checks and 14 entries were not different from the susceptible check. However, entry 2 (PI 518383) had both the lowest foliar rating of the PI lines and ranked first among all entries for the lowest storage rot. The root rating for entry 2 may have been affected by poor inherent root shape and may not necessarily represent a lack of resistance to BNYVV. The foliar rating and resistance to storage rot both suggest entry 2 should be reevaluated for resistance to BNYVV. Entry 2 may serve as a starting point for identifying additional sources of resistance to BNYVV and storage rots
Foliar insecticides for the control of curly top in Idaho sugar beet, 2017
Get PDFCurly top caused by Beet curly top virus (BCTV) is a widespread disease problem vectored by the beet leafhopper in semiarid sugar beet production areas. Host resistance is the primary defense against this problem, but resistance in commercial cultivars is only low to intermediate. The neonicotionoid seed treatments currently supplement this resistance to provide early season control. In order to identify other management options seven foliar insecticides were screened in 2017 on a commercial sugar beet cultivar approved for production since it contains curly top resistance. The plots were arranged in a randomized complete block design with eight replications. A curly top epiphytotic was created by releasing six viruliferous beet leafhoppers per plant at the eight-leaf growth stage on 14 June. Foliar symptoms were evaluated on 31 July and 21 August using a scale of 0-9 (0 = healthy and 9 = dead) in a continuous manner. Curly top symptom development was uniform and no other disease problems were evident in the plot area. The disease pressure in the test was moderately severe with good symptom development in the non-treated check. Based on visual ratings, root yield, and estimated recoverable sucrose, the foliar insecticides provided little or no influence on the control of curly top. However, the yields for all treatments except the insecticide seed treatment check indicate that the cultivar was severely infected during the study. These data show that sugar beet production in areas with curly top would likely suffer considerably without the neonicotinoid seed treatments
Kimberly sugar beet germplasm evaluated for rhizomania and storage rot resistance in Idaho, 2017
Get PDFRhizomania caused by Beet necrotic yellow vein virus (BNYVV) and storage losses are serious sugar beet production problems. To identify sugar beet germplasm lines with resistance to BNYVV and storage rots, 14 germplasm lines from the USDA-ARS Kimberly sugar beet program and four check cultivars were screened. The lines were grown in a sugar beet field infested with BNYVV during the 2017 growing season in a randomized complete block design with 6 replications. At harvest on 10 October 2017, roots were dug and evaluated for rhizomania symptoms and also placed in an indoor commercial sugar beet storage building. After 133 days in storage, samples were evaluated for the percentage of root surface area covered by fungal growth or rot. Rhizomania symptom development was uniform and other disease problems were not evident in the plot area. The BNYVV susceptible check had 98% foliar symptoms and a high root disease severity rating. The three resistant checks had 0 to 12% foliar symptoms and low root ratings. Based on root ratings, all entries had a level of resistance better than the susceptible check. However, KEMS43 and KD13/19-19 were the only entries with both root and foliar ratings not different from the resistant checks. Four additional entries (KEMS09-600, KEMS12/KPS24, KEMS06-600, and KEMS06) with both good foliar and storage ratings should be reevaluated for BNYVV resistance. These six entries just mentioned should also be considered as sources of storage rot resistance. These entries with superior performance will be released to the public and utilized in backcrossing breeding
Identifying challenges and opportunities for improved nutrient management through U.S.D.A's Dairy Agroecosystem Working Group
Get PDFNutrient management is a priority of U.S. dairy farms, although specific concerns vary across regions and management systems. To elucidate challenges and opportunities to improving nutrient use efficiencies, the USDA’s Dairy Agroecosystems Working Group investigated 10 case studies of confinement (including open lots and free stall housing) and grazing operations in the seven major
U.S. dairy producing states. Simulation modeling was carried out using the Integrated Farm Systems Model over 25 years of historic weather data. Dairies with a preference for importing feed and exporting manure, common for simulated dry lot dairies of the arid west, had lower nutrient use efficiencies at the farm gate than freestall and tie-stall dairies in humid climates. Phosphorus (P) use efficiencies ranged from 33 to 82% of imported P, while N use efficiencies were 25 to 50% of imported N. When viewed from a P budgeting perspective, environmental losses of P were generally negligible, especially from dry lot dairies. Opportunities for greater P use efficiency reside primarily in increasing on-farm feed production and reducing excess P in diets. In contrast with P, environmental losses of nitrogen (N) were 50 to 75% of annual farm N inputs. For dry lot dairies, the greatest potential for N conservation is associated with ammonia (NH3) control from housing, whereas for freestall and tie-stall operations, N conservation opportunities vary with soil and manure management system. Given that fertilizer expenses are equivalent to 2 to 6% of annual farm profits, cost incentives do exist to improve nutrient use efficiencies. However, augmenting on-farm feed production represents an even greater opportunity, especially on large operations with high animal unit densities
Winter wheat yield, quality, and nitrogen removal following compost- or manure-fertilized sugarbeet
Get PDFTo efficiently use N while protecting water quality, one must know how a second-year crop, without further N fertilization, responds in years following a manure application. In an Idaho field study of winter wheat (Triticum aestivum L.) following sugarbeet (Beta vulgaris L.), we determined the residual (second-year) effects of fall-applied solid dairy manure, either stockpiled or composted, on wheat yield, biomass, biomass N, protein, grain N removal, and agronomic N use efficiency (NUE). Along with a no-N control and urea (82 or 202 kg N/ha), first-year treatments at Site 1 included compost (218 and 435 kg estimated available N/ha) and manure (140 and 280 kg available N/ha) and at Site 2 compost (81 and 183 kg available N/ha) and manure (173 and 340 kg available N/ha). After application, compost and manure were incorporated into two silt loam-textured soils, a Greenleaf (Xeric Calciargid) at Parma in fall 2002 and 2003 and a Portneuf (Durinodic Xeric Haplocalcid) at Kimberly in fall 2002. Second-year wheat yield was greater, relative to the control, where organic N sources but not urea were applied at optimum rates for sugarbeet in two of three site-years, revealing a long-term benefit of compost and manure in reducing future N fertilizer costs. Where N-fertilized, grain yield was similar among urea and organic N sources that applied optimal amounts of plant-available N to the preceding year’s sugarbeet. Where optimal urea but greater organic N rates were applied, grain yield was always greater from manure than urea
Biochars reduce mine land soil bioavailable metals
Get PDFBiochars are being proposed as an amendment to remediate mine land soils. Therefore, two different feedstocks (pine beetle-killed lodgepole pine [Pinus contorta] and tamarisk [Tamarix spp.]), within close proximity to mine land affected soils, were used to create biochars in order to determine if they have the potential to reduce metal bioaccessibility. Four different mine land soils, contaminated with various amounts of cadmium, copper, lead, and zinc, received increasing amounts of biochar (0, 5, 10, and 15% by weight). Soil pH and metal bioaccessibility were determined, and the European Community Bureau of Reference sequential extraction procedure was employed to identify pools responsible for potential shifts in bioaccessibility. Increasing biochar application rates caused increases in soil pH (initial: 3.97; final: 7.49) and 55 to 100% (no longer detectable) decreases in metal bioaccessibility. The sequential extraction procedure supported the association of cadmium with carbonates, copper and zinc with oxyhydroxides and carbonates, and lead with oxyhydroxides; these phases were likely responsible for the reduction in heavy metal bioaccessibility. This study proved that feedstocks local to abandoned mining operations could subsequently be used to create biochars and reduce heavy metal bioaccessibility in mine land soils