The North American long-term soil productivity experiment: Findings from the first decade of research   总被引：1，自引：0，他引：1  

Robert F. Powers  D. Andrew Scott  Felipe G. Sanchez  Richard A. Voldseth  Deborah Page-Dumroese  John D. Elioff  Douglas M. Stone 《Forest Ecology and Management》2005,220(1-3):31-50

First decade findings on the impacts of organic matter removal and soil compaction are reported for the 26 oldest installations in the nation-wide network of long-term soil productivity sites. Complete removal of surface organic matter led to declines in soil C concentration to 20 cm depth and to reduced nutrient availability. The effect is attributed mainly to the loss of the forest floor. Soil C storage seemed undiminished, but could be explained by bulk density changes following disturbance and to decomposition inputs of organic C from roots remaining from the harvested forest. Biomass removal during harvesting had no influence on forest growth through 10 years. Soil compaction effects depended upon initial bulk density. Soils with densities greater than 1.4 Mg m⁻³ resisted compaction. Density recovery was slow, particularly on soils with frigid temperature regimes. Forest productivity response to soil compaction depended both on soil texture and the degree of understory competition. Production declined on compacted clay soils, increased on sands, and generally was unaffected if an understory was absent.  相似文献   

Cryopreservation of yellow-poplar and sweetgum embryogenic cultures     

Vendrame  Wagner A.  Holliday  Christopher P.  Montello  Paul M.  Smith  Dale R.  Merkle  Scott A. 《New Forests》2001,21(3):283-292

Cryopreservation has become anessential tool for operational application offorest tree embryogenic cultures, due to thelong evaluation periods needed for treesregenerated from these cultures. Fiveyellow-poplar (Liriodendron tulipifera)and seven sweetgum (Liquidambar spp.)embryogenic culture lines werestored in liquid nitrogen for 48 hours, afterwhich they were thawed and tested for regrowthand ability to produce somatic seedlings.Combinations of two sorbitol pretreatments andthree dimethylsulfoxide (DMSO) cryoprotectantlevels were evaluated for their impact onrecovery following cryogenic storage. The bestresults were obtained with 0.4 M sorbitol and5% DMSO, which provided 100% recovery.Somatic seedlings were regenerated from allculture lines and treatments, except for atransgenic sweetgum line.  相似文献   

One-day rate measurements for estimating net nitrification potential in humid forest soils   总被引：2，自引：0，他引：2  

Donald S. Ross  Guinevere Fredriksen  Austin E. Jamison  Beverley C. Wemple  Scott W. Bailey  James B. Shanley  Gregory B. Lawrence 《Forest Ecology and Management》2006,230(1-3):91-95

Measurements of net nitrification rates in forest soils have usually been performed by extended sample incubation (2–8 weeks), either in the field or in the lab. Because of disturbance effects, these measurements are only estimates of nitrification potential and shorter incubations may suffice. In three separate studies of northeastern USA forest soil surface horizons, we found that laboratory nitrification rates measured over 1 day related well to those measured over 4 weeks. Soil samples of Oa or A horizons were mixed by hand and the initial extraction of subsamples, using 2 mol L⁻¹ KCl, occurred in the field as soon as feasible after sampling. Soils were kept near field temperature and subsampled again the following day in the laboratory. Rates measured by this method were about three times higher than the 4-week rates. Variability in measured rates was similar over either incubation period. Because NO₃⁻ concentrations were usually quite low in the field, average rates from 10 research watersheds could be estimated with only a single, 1-day extraction. Methodological studies showed that the concentration of NH₄⁺ increased slowly during contact time with the KCl extractant and, thus, this contact time should be kept similar during the procedure. This method allows a large number of samples to be rapidly assessed.  相似文献   

Evaluation of the Diagnostic Accuracy of Conventional 2‐Dimensional and 3‐Dimensional Computed Tomography for Assessing Canine Sacral and Pelvic Fractures by Radiologists,Orthopedic Surgeons,and Veterinary Medical Students          下载免费PDF全文

Sri Kumar Jamie Senthirajah BS  Sarah Nemanic DVM  PhD  Diplomate ACVR  Wendy Baltzer DVM  PhD  Diplomate ACVS  Jennifer Warnock DVM  PhD  Diplomate ACVS  Katelyn Hollars BS  Scott S. Lee  Gerd Bobe PhD 《Veterinary surgery : VS》2015,44(6):694-703

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Effects of aluminum hinged shoes on the structure of contracted feet in Thoroughbred yearlings     

Kousuke TANAKA  Atsushi HIRAGA  Toshiyuki TAKAHASHI  Atsutoshi KUWANO  Scott Edward MORRISON 《Journal of Equine Science》2015,26(2):67-71

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Prevalence of methicillin‐resistant Staphylococcus spp. in the conjunctival sac of healthy dogs          下载免费PDF全文

Meredith C. Mouney  Jean Stiles  Wendy M. Townsend  Lynn Guptill  J. Scott Weese 《Veterinary ophthalmology》2015,18(2):123-126

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Insecticidal and anti-microbial activity of bio-oil derived from fast pyrolysis of lignin,cellulose, and hemicellulose     

Hossain  Mohammad M.  Scott  Ian M.  McGarvey  Brian D.  Conn  Kenneth  Ferrante  Lorenzo  Berruti  Franco  Briens  Cedric 《Journal of pest science》2015,88(1):171-179

Journal of Pest Science - Conflicting views regarding synthetic pesticides include the successful use as pest management tools for agriculture and forestry on one hand and the threats to components...  相似文献   

PLUS: a regional groundwater assessment and ranking tool     

Jackson SH  Hendley P  Cheplick M 《Journal of agricultural and food chemistry》2007,55(14):5408-5415

There has been interest within the pesticide regulatory community in developing a tool that can provide estimates of potential pesticide exposure in shallow groundwater across an intended use area. Therefore, industry initiated an investigative project based on the PRZM 3.12 model, which uses regional soils and weather in an easy to use interface. The goal of this proof-of-concept is to facilitate the refinement of groundwater exposure estimates. The focus of this paper is to report the effectiveness of the tool as a regional estimator of potential groundwater contamination.  相似文献   

Detection of ruminant meat and bone meals in animal feed by real-time polymerase chain reaction: result of an interlaboratory study   总被引：1，自引：0，他引：1  

Prado M  Berben G  Fumière O  van Duijn G  Mensinga-Kruize J  Reaney S  Boix A  von Holst C 《Journal of agricultural and food chemistry》2007,55(18):7495-7501

The commercialization of animal feeds infected by prions proved to be the main cause of transmission of bovine spongiform encephalopathy (BSE). Therefore, feed bans were enforced, initially for ruminant feeds, and later for all feeds for farmed animals. The development and validation of analytical methods for the species-specific detection of animal proteins in animal feed has been indicated in the TSE (Transmissible Spongiform Encephalopathies) Roadmap (European Commission. The TSE (Transmissible Spongiform Encephalopathy) roadmap. URL: http://europa.eu.int/comm/food/food/biosafety/bse/roadmap_en.pdf, 2005) as the main condition for lifting the extended feed ban. Methods based on polymerase chain reaction (PCR) seem to be a promising solution for this aim. The main objective of this study was to determine the applicability of four different real-time PCR methods, developed by three National expert laboratories from the European Union (EU), for the detection and identification of cattle or ruminant species in typical compound feeds, fortified with meat and bone meals (MBM) from different animal species at different concentration levels. The MBM samples utilized in this study have been treated using the sterilization condition mandatory within the European Union (steam pressure sterilization at 133 degrees C, 3 bar, and 20 min), which is an additional challenge to the PCR methods evaluated in this study. The results indicate that the three labs applying their PCR methods were able to detect 0.1% of cattle MBM, either alone or in mixtures with different materials such as fishmeal, which demonstrates the improvement made by this technique, especially when compared with results from former interlaboratory studies.  相似文献   

Processes affecting the dissipation of the herbicide isoxaflutole and its diketonitrile metabolite in agricultural soils under field conditions     

Papiernik SK  Yates SR  Koskinen WC  Barber B 《Journal of agricultural and food chemistry》2007,55(21):8630-8639

Two-year field dissipation studies were conducted in three soil types in Minnesota to examine the processes affecting the dissipation of the herbicide isoxaflutole and its phytotoxic diketonitrile metabolite (DKN) under relatively cool, wet soil conditions. Plots of cuphea were treated with isoxaflutole and potassium bromide, a nonsorbed, nondegraded tracer. Replicate soil cores were collected six times during the growing season to a depth of 1 m, and the bromide or herbicide concentration was measured in each of five depth increments. The dissipation half-life (DT50) of isoxaflutole + DKN was 8-18 days in each soil. Bromide and herbicide concentrations were low at depths >40 cm throughout the study, and herbicide concentrations in soil 100 days after application were usually undetectable. Simulation modeling using Hydrus-1D for the loam soil suggested that plant uptake was an important mechanism of dissipation.  相似文献