David D. Tarkalson

Effect of Growth Promotants on the Occurrence of Endogenous and Synthetic Steroid Hormones on Feedlot Soils and in Runoff from Beef Cattle Feeding Operations

Supplements and growth promotants containing steroid hormones are routinely administered to beef cattle to improve feeding efficiency, reduce behavioral problems, and enhance production. As a result, beef cattle manure will contain both synthetic steroids as well as a range of endogenous steroids including androgens, estrogens, and progestogens. A two-year controlled study was conducted in which beef cattle were administered steroid hormones via subcutaneous implants and feed additives and the occurrence of 16 endogenous and synthetic steroid hormones and metabolites was evaluated in runoff from beef cattle feedlots and in manure and soil collected from feedlot surfaces. Samples were extracted and analyzed using liquid chromatography tandem mass spectrometryfor metabolites of the synthetic androgen trenbolone acetate, 17α-trenbolone, 17β-trenbolone, for the nonsteroidal semisynthetic estrogen agonist, α-zearalanol, and the synthetic progesterone melengesterol acetate, as well as a wide range of endogeneous estrogens, androgens, and fusarium metabolites. Synthetic steroids including trenbolone metabolites and melengestrol acetate were detected in fresh manure and in feedlot surface soils from cattle administered synthetic steroids at concentrations up to 55 ± 22 ng/g dry weight (dw) (17α-trenbolone) and 6.5 ± 0.4 ng/g dw (melengesterol acetate). Melengesterol acetate was detected in 6% of runoff samples from feedlots holding cattle administered synthetic steroids at concentrations ranging up to 115 ng/L. The presence of melengesterol acetate in runoff from beef cattle feeding operations has not been previously reported. Synthetic steroids were not detected in manure or runoff from control cattle. A wide range of endogenous hormones were detected in runoff and feedlot surface soils and manure from cattle given synthetic steroids and from control cattle, with no statistically significant differences in concentration. These results indicate that runoff from confined animal production facilities is of environmental and public health concern regardless of the use of growth promotants.

Zeolite Soil Application Method Affects Inorganic Nitrogen, Moisture, and Corn Growth

Adoption of new management techniques that improve soil water storage and soil N plant availability yet limit N leaching may help improve environmental quality. A benchtop study was conducted to determine the influence of a single urea fertilizer rate (224 kg N ha−1) applied with band or fully mixed zeolite (clinoptilolite) application rates (up to 90 Mg ha−1) on NH4-N and NO3-N concentrations in a Portneuf silt loam (coarse-silty, mixed, mesic, durinodic Xeric Haplocalcid). Two additional greenhouse experiments were carried out to test the soil moisture status and corn (Zea mays L.) growth in a Wolverine sand (mixed, frigid Xeric Torripsamment). Mixing urea fertilizer into silt loam soil resulted in greater urea mineralization as compared with band application of fertilizer + zeolite, and the mixed zeolite was more effective at sorbing and protecting NH4-N against nitrification. Increasing the rate of mixed zeolite into sandy soil increased the soil moisture content, and mixed zeolite soils contained 1.3% more soil moisture as compared with band zeolite applications. After 6 weeks of corn growth in amended sandy soil, zeolite application at 22 Mg ha−1 seemed to increase corn weight compared with controls. However, increasing zeolite rate up to 90 Mg ha−1 caused a decrease in corn weight, likely caused by the elevated zeolite Na content (3%). Fully mixing zeolite into soil reduced the rate of nitrification likely because of NH4+ adsorption in the zeolite mineral lattice. Thus, mixing zeolite into soil may reduce the leaching of inorganic N. Mixing may also improve the soil water status, although initial leaching of zeolite-borne Na may be necessary before growing crops.

Phosphorus Mobility in Soil Columns Treated With Dairy Manures and Commercial Fertilizer

The concentration of animal production in some areas of the United States has led to concern about the environmental fate of manure-derived phosphorus (P) in soils. A column study was conducted to quantify P leaching in a calcareous soil treated with monoammonium phosphate (MAP), two solid dairy manures (D1S and D2S), and two liquid dairy manures (D1L and D2L). A control with no P application was also included. Treatments were applied at 166 kg P ha−1 to columns packed with 20 cm of a Warden fine sandy loam (coarse-loamy, mixed superactive, mesic Xeric Haplocalcids) in a completely randomized design with four replications and housed in a climate-controlled growth chamber. Simulated irrigation water was added to the columns at a rate of 47.4 mm (450 mL) during 13 events during a 9-week period, with leachate collected, volume recorded, and concentrations of total organic carbon (TOC) and total P (TP) determined for each event. At the end of the leaching events, each soil column was divided into eight 2.5-cm segments. Then, soil was air-dried, ground, and analyzed for TP, total carbon, calcium (Ca), iron, and manganese, and water-soluble P. The masses of TP and TOC in leachate were in the order D1L = D2L > MAP = D1S = D2S = Control. There was a positive linear relationship between the cumulative mass of TOC and cumulative mass of TP lost in leachate over all manure treatments (r2 = 0.98). The masses of TP and water-soluble P for treatments in the entire soil columns were in the order MAP > D1L = D2L > D1S = D2S = Control. Masses of P and C in leachate and soil show that P mobility in soil was in the order liquid dairy manures > MAP > solid dairy manures. At the end of the study, the total C was greater in the surface 2.5 cm of the soil columns for the solid manure treatments compared with the other treatments/depth combinations. The greater leaching of P in the liquid manure treatments compared with the solid manure treatments may be caused by a combination of factors including microbial activity, organically complexed metals, coating of P adsorption sites on clay particles by organic C compounds, and P-Ca and P-aluminum reactions.

Copper Impacts on Corn, Soil Extractability, and the Soil Bacterial Community

Dairies use CuSO4 footbaths to control hoof infections, with Cu accumulation in agricultural soils realized when spent footbaths are disposed of in waste lagoons and subsequently used for irrigation. We investigated the effect of Cu applications (up to 1000 mg kg−1) to a Xeric Haplocalcid (Declo series) and a Typic Calciaquoll (Logan series) on corn (Zea mays L.) growth and Cu concentration, soil total and diethylenetriaminepentaacetic acid (DTPA)-extractable Cu, and the soil bacterial community diversity using ribosomal intergenic spacer analysis followed by cluster analysis. Copper application up to 250 mg kg−1 did not affect corn growth; at 500 mg Cu kg−1, corn growth was reduced by up to 80%. The 250 and 500 mg kg−1 Cu application rates increased corn Cu content grown in Declo soil, whereas the 500 mg kg−1 Cu application rate increased Logan soil corn Cu. Regardless of initial application rate, 60% to 75% of the added Cu was still plant available. Comparing DTPA-extractable Cu with corn Cu concentrations for the Declo and Logan soils, 130 or 220, and 215 or 300 mg kg−1 of DTPA-extractable soil Cu would be detrimental in terms of sheep and cattle dietary Cu intake, respectively. As Cu concentrations increased, bacterial diversity decreased, and species evenness remained high, suggesting that few phylotypes predominated within the ribosomal intergenic spacer analysis profiles. To prevent excessive corn Cu accumulation and negative impacts on the soil bacterial community, it is recommended that available soil Cu not exceed 130 mg kg−1 in agroecosystems associated with these soil series.ABBREVIATIONS ANOVA: analysis of variance; DTPA: diethylenetriaminepentaacetic acid; OM: organic matter; RISA: ribosomal intergenic spacer analysis.

Runoff Phosphorus Losses as Related to Soil Test Phosphorus and Degree of Phosphorus Saturation on Piedmont Soils Under Conventional and No-Tillage

Abstract Elevated soil phosphorus (P) concentrations on agricultural land from the application of P in fertilizers and animal manures have increased the potential for excessive P losses in runoff to nutrient-sensitive waters. This study was conducted to determine P losses in runoff from agricultural land in the Piedmont region of the southeastern U.S. with varying soil P levels resulting from past applications of broiler litter and inorganic P fertilizers. The correlations between soil P content and P in runoff can be used to validate and develop P loss-assessment tools for Piedmont soils of the southeastern US. Rainfall simulation at rates of 6.35 cm hr−1 were utilized to collect runoff samples from cropland under conventional tillage (CT) and no tillage (NT) with a range of initial P concentrations. Runoff samples were collected at 5-min intervals for 30 min and analyzed for reactive P (RP), algal-available P (AAP), and total P (TP). Concentration of RP in runoff from CT and NT plots was positively correlated with Mehlich-3 extractable P (M3 STP) (r 2 = 0.70 and 0.67, respectively) and oxalate extractable degree of P saturation (DPS) (r 2 = 0.62 and 0.57, respectively). A Mehlich-3 extractable P concentration of 294 mg P kg−1 and a DPS of 65% corresponded to 1 mg RP L−1 in runoff from NT plots. There was a significant linear relationship between M3 STP concentration and DPS on CT and NT plots. Results of this study indicate that both M3 STP concentration and DPS can be used to help predict P losses from a typical Piedmont soil managed with CT and NT cultivation. Overall, these soil tests predicted P concentration in runoff more effectively than P mass losses in runoff.

A phosphorus budget of a poultry farm and a dairy farm in the southeastern U.S., and the potential impacts of diet alterations

Current and potential environmental problems associated with P transport from lands receiving high application rates of animal waste are a major concern. Phosphorus management strategies are needed to reduce P loading on land. This study was conducted to compare on-farm P budgets for a modern broiler farm and a dairy farm under traditional diets and management practices. Phosphorus inputs, recycling and outputs were assessed for both farms. A typical broiler and a dairy farmer from North Carolina were interviewed and pertinent information for the study was obtained, in cooperation with extension agents, and other professionals associated with the farms. The annual on-farm P surplus for the broiler farm was 6,380 kg, while that for the dairy farm was 1,141 kg. This corresponds to an annual application of 65 kg P ha−1 for the broiler farm and 20 kg P ha−1 for the dairy farm in excess of removal. The potential for reducing P surpluses by the addition of phytase enzymes and/or the use of low phytic acid corn (Zea mays L.) feed in the broiler farm diet was also assessed. Estimates by animal nutritionists indicate that feed supplementation with phytase enzyme can reduce the broiler farms P surplus by 33%. The use of low phytic acid corn can reduce the surplus by 49% and a combination of the two can reduce the surplus by 58%. In this study, the incorporation of soybean (Glycine max (L.) Merr.) and alfalfa (Medicago sativa) land into the waste utilization plan of the dairy farm decreases the annual P surplus from 20 to 9 kg P ha−1. The use of new feed technology and expanding waste application to a larger land base can significantly alter the P budgets of broiler and dairy farms and reduce P surpluses, minimizing the risk of environmental problems.

Use of Time Domain Reflectometry for Continuous Monitoring of Nitrate-Nitrogen in Soil and Water

ABsTRAcr. Nitrate-Nitrogen (NO3-N) losses to ground and surface water are an environmental and agronomic concern in modern crop production systems in the Central Great Plains. Monitoring techniques for nitrogen use in agricultural production are needed to increase crop yield, optimize nitrogen use, and reduce NO3-N leaching. Time domain reflectometry (TDR) could potentially be calibrated to continuously measure NO3-N in soil and water. The objectives of this study were to: (1) evaluate the effect of different factors affecting the response of the bulk electrical conductivity (ECb) sensed by TDR, (2) compare the sensitivity and differences between vertically-installed and horizontally-installed probes for measuring NO3-N leaching in the soil profile, and (3) evaluate the feasibility of using TDR to measure changes in NO 3-N concentration in an irrigated agricultural soil. Studies were conducted in the laboratory and in the field at the University of Nebraska West Central Research and Extension Center in North Platte, Nebraska. Temperature of the medium (Ts), solute concentration, TDR cable length, and volumetric soil water content (O p) all influenced and were linearly related to the bulk electrical conductivity (ECb) sensed by the TDR probes. In the field, measured soil NO 3-N correlated well with values estimated using TDR measurements of ECb, corrected for changes in CC and Ts. These results indicated that TDR, if properly calibrated for a particular soil, could be used to continuously monitor NO3-N in soil, and should also be well-suited for monitoring NO3-N in groundwater and surface water. It is, however, important to perform the calibration over a long enough period of time to include the expected range of 19,,, Ts, and NO 3-N values to obtain adequate accuracy.

Fly ash as a liming material for corn production

Fly ash produced as a by-product of subbituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was conducted to determine if fly ash produced from the Nebraska Public Power District Gerald Gentleman Power Station located in Sutherland, NE could be used as an alternative liming material. This study had the following objectives: 1) compare the effects of fly ash on soil pH with other common agricultural lime materials; 2) determine the effects of fly ash on percent Al saturation in selected soils; and 3) determine the effects of fly ash on corn grain yields. Combinations of dry fly ash (DFA), wet fly ash (WFA), beet lime (by-product of sugar beet [Beta vulgaris L.] processing) (BL), and agricultural lime (AGL) were applied at rates ranging from 0.43 to 1.62 times the recommended lime rate to plots on four acidic soils (Anselmo fine sandy loam, Hord fine sandy loam, Holdrege sandy loam, and Valentine fine sand). Soil samples were collected to a depth of 0.2 m from plots and analyzed for pH before lime applications and twice periodically after lime application. The Hord and Valentine soils were analyzed for exchangeable Ca, Mg, K, Na, and Al for determination of percent Al saturation on selected treatments and sampling dates. Corn grain yields were determined annually. Depending on the lime source, soil pH increased in the upper 0.2 m of soil the year after application compared with the pre-application soil pH values for some sites and years, whereas in others there were no significant increases in pH. However, all lime materials at each site failed to raise the soil pH in the upper 0.2 m of all the treatments and soil types to the target pH of 6.5. Fly ash and AGL treatments did not significantly increase corn grain yields compared with the control on the Anselmo, Hord, and Holdrege soils. At the Hord site, AGL and DFA significantly reduced percent Al saturation by 3.1% and 3.7% compared with the control 5 years after application, respectively. Fly ash did not negatively affect corn grain yields compared with AGL. Yields were 12,472, 12,233, and 12,177 kg ha−1 for the Anselmo, Holdrege, and Hord sites averaged over all treatments and years. The lack of yield response to lime additions was potentially a result of lime materials not raising the soil pH to sufficient levels, higher subsoil pH values, or the exchangeable Al not being high enough prior to lime material application to reduce grain yields in these soils. We conclude that the fly ash utilized in this study and applied at rates in this study, increases soil pH comparable to agricultural lime and is an appropriate alternative liming material.

Effect of composting on the fate of steroids in beef cattle manure.

In this study, the fate of steroid hormones in beef cattle manure composting is evaluated. The fate of 16 steroids and metabolites was evaluated in composted manure from beef cattle administered growth promotants and from beef cattle with no steroid hormone implants. The fate of estrogens (primary detected as estrone), androgens, progesterone, and the fusarium metabolite and implant α-zearalanol was monitored in manure compost piles. First-order decay rates were calculated for steroid half-lives in compost and ranged from 8 d for androsterone to 69 d for 4-androstenedione. Other steroid concentration data could not be fit to first-order decay models, which may indicate that microbial processes may result in steroid production or synthesis in composting systems. We demonstrate that composting is an effective strategy to remove steroid hormones from manure. Total steroid hormone removal in composted beef cattle manure ranged from 79 to 87%.

Evaluation of In-Row Plant Spacing and Planting Configuration for Three Irrigated Potato Cultivars

Research studies have shown that planting potatoes (Solanum tuberosum L.) in a bed configuration can improve water movement into the potato root zone. However, plant spacing recommendations are needed for potatoes planted in a bed configuration. This study was conducted to evaluate the effect of in-row plant spacing and planting configuration on yield of Russet Burbank, Russet Norkotah, and Ranger Russet potatoes under sprinkler irrigation. For the three cultivars, the effect of in-row plant spacing (three spacing treatments) for each planting configuration (4 row conventional ridged-row [4RC], 5 row bed [5RB], and 7 row bed [7RB]), and the effect of planting configuration at a uniform population on total tuber yield, U.S. No. 1 tuber yield, tubers per ha, average size (by weight), and large tuber yield were investigated at the USDA-ARS Northwest Irrigation & Soils Research Lab in Kimberly, ID on a Portneuf silt loam (coarse-silty mixed mesic Durixerollic Calciorthid) in 2008 and 2009. The greatest influence of in-row plant spacing was on average size and tubers per ha. In general, as in-row plant spacing increased (plant population decreased) the average tuber size increased and tubers per ha decreased. There was little influence of in-row spacing on measured production variables under the bed planting configurations except for tubers per ha which generally increased with narrower plant spacing. For Russet Norkotah and Ranger Russet there were few differences in measured production variables between planting configuration treatments. For Russet Burbank, the 4RC planting configuration had 14.6% significantly greater total tuber yield than the 7RB planting configuration, 20.2% greater U.S. No. 1 tuber yield than both bed planting configurations, and 25.2 and 29.9% greater large tuber yield than the 5RB and 7RB planting configurations, in 2009. Optimum production of Russet Norkotah and Ranger Russet potatoes is possible under all the planting configurations and plant spacing range evaluated in this study, granting growers flexibility in their systems, however, evidence from this study suggests that production of Russet Burbank may be less suited to bed planting configurations.ResumenInvestigaciones han demostrado que plantar papa (Solanum tuberosum L.) en una configuración de cama puede mejorar el movimiento del agua hacia la zona de la raíz de la papa. No obstante, se necesitan las recomendaciones de espaciamiento de plantas de papa sembradas en la configuración de cama. Este estudio se condujo para evaluar el efecto del espaciamiento entre plantas en el surco y de configuración de plantación en el rendimiento de papa Russet Burbank, Russet Norkotah, y Ranger Russet bajo riego por aspersión. En 2008 y 2009, se les investigó a estas tres variedades el efecto en espaciamiento entre plantas en el surco (tres tratamientos de distancias) para cada configuración de plantación (4 surcos convencionales [4RC], cama de 5 hileras [5RB], y cama de 7 hileras [7RB]), y el efecto de la configuración de la plantación a una población uniforme, sobre rendimiento total de tubérculo, rendimiento de U.S. No. 1, tubérculos por ha, tamaño promedio (por peso), y rendimiento de tubérculo grande, en el Laboratorio de Investigación sobre Riego y Suelos del Noroeste del USDA-ARS en Kimberly, ID, en un suelo limoso Portneuf (mezcla de limo-grueso con medio Durixerollico Calciortido). La mayor influencia del espaciamiento de las plantas dentro del surco fue en el promedio de tamaño y tubérculos por ha. En general, a medida que aumentó el espaciamiento entre plantas en el surco (disminución en la población de plantas) el tamaño promedio del tubérculo aumentó y los tubérculos por ha disminuyeron. Hubo poca influencia en los espaciamientos dentro del surco en las variables de producción medidas bajo las configuraciones de plantación en camas, excepto para tubérculos por ha, que generalmente se aumentaron con espaciamientos más cortos entre plantas. Para Russet Norkotah y Ranger Russet hubo pocas diferencias en las variables medidas de producción entre los tratamientos de configuración de plantación. Para Russet Burbank, la configuración 4RC tuvo 14.6% significativamente más rendimiento de tubérculo total que la de 7RB, 20.2% más rendimiento de tubérculo U.S. No. 1 que las dos configuraciones de cama, y 25.2 y29.9% más de rendimiento de tubérculo grande que las configuraciones 5RB y 7RB en el 2009. Es posible la producción óptima de papa de Russet Norkotah y Ranger Russet bajo todas las configuraciones y de los rangos de espaciamiento entre plantas evaluados en este estudio, garantizándole a los productores flexibilidad en sus sistemas. No obstante, la evidencia de este estudio sugiere que la producción de Russet Burbank pudiera ser menos deseable para las configuraciones de plantación en camas.