Is air-drying of soil samples an appropriate step in determining plant available potassium for corn?     

Manbir Kaur Rakkar  David Franzen  Amitava Chatterjee 《Journal of plant nutrition》2016,39(13):1979-1988

Potassium (K) fertilizer recommendations are mainly based on air -dried soil samples which can lead to over- or under-estimation of plant available soil K. Three on-farm trials were conducted in North Dakota and Minnesota to determine the variation of soil test-K between air-dried (K_Dry) and field moist (K_Moist) soil samples. The differences between K_Dry and K_Moist decreased exponentially as soil K increased, but increased linearly with increasing soil moisture. Soil drying influenced the plant available soil K-test value, producing higher K values compared to the moist soil K. It is unclear based on these initial experiments which method might produce a more predictable K critical value to aid in directing K application for corn in this region.  相似文献   

Quantitative monitoring of airborne lead pollution by a foliose lichen     

David Schwartzman  Margaret Kasim  Lorin Stieff  James H. Johnson Jr. 《Water, air, and soil pollution》1987,32(3-4):363-378

The potential use of lichens as quantitative monitors of airborne heavy metal pollution has been demonstrated by measurements of Po²¹⁰, Pb, Cd, Zn, and V levels in sequential growth of the foliose lichen Pseudoparmelia baltimorensis from three localities in the greater Washington, D.C. area. Samples were dated using the growth rate measured by Lawrey and Hale (1977). Po²¹⁰, Pb, and V increase with age in a given colony. Higher levels of Pb, V, Cd, and Zn are present in samples from the two more polluted sites. The retention of heavy metals is consistent with trapping by an ion exchange mechanism. Since Po²¹⁰ is the daughter product of in situ decay of Pb²¹⁰, accumulated from atmospheric fallout of known rate, its levels can be used to calculate trapping efficiencies of Pb and retrospective fallout rates. These rates are similar to published data from rural and urban areas.  相似文献   

Differentiation of physical from chemical toxicity in solid waste fish bioassays     

Peter M. Chapman  J. David Popham  Jack Griffin  David Leslie  John Michaelson 《Water, air, and soil pollution》1987,33(3-4):295-308

This study showed that particulate (i.e., physical) toxicity was responsible for rainbow trout deaths in bioassays with two separate solid wastes. This conclusion was based on: (1) fish necropsies which indicated physical damage to gills but no evidence of chemical damage to liver or kidney, (2) chemical analyses which indicated that levels of Priority Pollutants and other target compounds were too low to cause the observed toxicity, (3) structural and chemical analyses of the waste particles which showed that these consisted of inert materials, and (4) the use of centrifugation techniques to remove most of the suspended particulate material in bioassay tanks resulting in an elimination of most of the toxicity. The particles associated with the lethal effects were approximately 5 to 10 μm in size. Regulatory testing of solid wastes must distinguish physical and chemical toxicity since disposal options can vary depending on the mode of toxicity. For instance, chemical toxicity raises concern regarding leaching through soils into groundwater, whereas if physical particles are responsible for toxicity, such leaching is not of concern.  相似文献   

Plant uptake assay to determine bioavailability of inorganic contaminants     

David R. Dreesen  Edward J. Cokal 《Water, air, and soil pollution》1984,22(1):85-93

A laboratory technique has been developed to rapidly assess the potential uptake of contaminants by plants growing into waste burial sites. A soil-less planting media was used to provide rapid plant growth and reproducible growing conditions. The uptake of contaminants by several plant species grown on uranium mill tailings materials has been examined. The bioavailability of Mo, Se, Cl, and other trace metals in tailings was greater than in a surface soil from a uranium mining area. Significant differences in nutrient and contaminant contents in aboveground biomass were found between species.  相似文献   

Soil respiration on reclaimed coal-mine spoil     

Andrew Gildon  David L. Rimmer 《Biology and Fertility of Soils》1993,16(1):41-44

Summary Measurements of soil respiration were made at a number of soil-covered reclaimed coal-mine spoil sites. Many chemical and physical soil factors likely to affect the respiration were also measured. A combination of principal component, cluster, and multiple regression analyses was used to indicate the important factors. These were found to be water-holding capacity and organic matter content. In some cases soil pH was also a controlling factor.  相似文献   

Development of multiclass methods for drug residues in eggs: silica SPE cleanup and LC-MS/MS analysis of ionophore and macrolide residues   总被引：1，自引：0，他引：1  

Heller DN  Nochetto CB 《Journal of agricultural and food chemistry》2004,52(23):6848-6856

A method was developed that is suitable for screening eggs for a variety of nonpolar residues in a single procedure. Residues are extracted by silica solid-phase extraction (SPE). Analysis is conducted via reverse-phase gradient liquid chromatography, electrospray ionization, and tandem ion trap mass spectrometry. For screening purposes (based on a single precursor-product ion transition) the method can detect ionophore (lasalocid, monensin, salinomycin, narasin) and macrolide (erythromycin, tylosin) residues in egg at approximately 1 ng/mL (ppb) and above and novobiocin residues at approximately 3 ppb and above. Conditions are described for confirmatory analysis based on multiple ions in the product ion spectrum. The extraction efficiency for ionophores was estimated at 60-85%, depending on drug. Recovery of macrolides and novobiocin was not as good (estimated at 40-55% after a hexane wash of the final extract was included), but the method consistently screened and confirmed these residues at concentrations below the target of 10 ppb. The method was applied to eggs from hens dosed with each drug individually. Lasalocid was found to have the highest probability of detection in eggs based on its high ionization efficiency and higher rate of deposition relative to the other drugs. The method is part of a larger scheme to provide surveillance methods for a wide variety of drug residues in eggs.  相似文献   

The effect on model identifiability of allowing different relocation rates for live and dead animals in the combined analysis of telemetry and recapture data     

Marlina?D.?NasutionEmail author  Cavell?Brownie  Kenneth?H.?Pollock  Roger?A.?Powell 《Journal of Agricultural, Biological & Environmental Statistics》2004,9(1):27-41

Models are described for the joint analysis of live-trapping and radio telemetry data from a study on black bears (Ursus americanus) in which all animals received ear tags and a subset also received radio tags. Concerns about bias in survival estimates led to investigation of identifiability and estimator precision for a series of models that allowed differenttelemetry relocation rates for living and dead animals, in addition to emigration and seasonal variation in survival. Identifiability was determined by showing that the expected information matrix was nonsingular. Models with fidelity constant across time, and with the same degree of time specificity for survival rates and relocation rates for dead animals, were determined to be nonidentifiable. More general models, with a greater degree of time specificity for survival rates, were near-singular, and estimators under these near-singular models had poor precision. Analysis of data from the study on black bears illustrated that estimates of survival have poor precision when relocation rates are estimated separately for live and dead animals. It is recommended that the effort expended to relocate both living and dead animals be consistently high in each telemetry survey, so that relocation rates will be high and constant across time and mortality status.  相似文献   

Influence of pH and calcium on the growth,polysaccharide production and symbiotic association of<Emphasis Type="Italic"> Sinorhizobium meliloti</Emphasis> SEMIA 116 with alfalfa roots     

Carolina?Delavechia  Eugenio?Hampp  Adriana?Fabra  Stella?CastroEmail author 《Biology and Fertility of Soils》2003,38(2):110-114

The Sinorhizobium -legume interaction is sensitive to a number of environmental factors, soil acidity being one of the most important. In the typic Hapludoll soil of the central-southern region of Córdoba (Argentine) it was found that the nodulation of alfalfa ( Medicago sativaL.) roots was impaired with a reduction in shoot dry matter under conditions of soil acidity (pH 5.5) Our results showed that the addition of lime as dolomitic limestone at a concentration of 1 t ha ^-1to acid soil caused a significant increase in the nodulation of alfalfa roots inoculated with the strain Sinorhizobium meliloti SEMIA 116 (recommended inoculum for alfalfa) in the greenhouse experiments. The success of the lime treatment may be related not only to an increase in the pH values but also to an increase in the Ca concentration, improving the growth of S. meliloti and its nodulation ability under acidic conditions. In this study, we also demonstrated an increment in the bacterial growth rate as well as in the production of exopolysaccharides and lipopolysaccharides under low pH (5.5) and a high Ca concentration (5 mM) in the culture medium.  相似文献   

Verification of identities in global cacao germplasm collections     

Lambert Motilal  David Butler 《Genetic Resources and Crop Evolution》2003,50(8):799-807

The ex situ conservation of cacao genetic resources is in the form of field genebanks. Misidentified trees though, represent a serious problem to (i) curators, who need to capture genetic diversity, and (ii) users of germplasm material, who must be certain of the identities of the accessions for proper evaluation of their results. The presence of mislabelled trees was assessed from data compiled in the International Cocoa Germplasm Database (ICGD) 2000 v4.1CD-ROM, which contains the published records of cacao accessions in global holdings. Circumstantial evidence revealed that many germplasm collections, especially those in Brazil (CEPEC), Colombia (ICA), Costa Rica (CATIE), Côte d'Ivoire, Mexico, Malaysia, Togo, Trinidad (ICG,T) and Venezuela (EEC) probably possessed misidentified material. The severity of the problem ranged from 15–44 % and is suggested as an area for immediate resolution. Based upon the morphological data provided by the ICGD CD-ROM, several accessions were highly suspect, including 'EET 19 [ECU]', 'EET 48 [ECU]', 'EET 162 [ECU]', 'ICS 1', 'ICS 6', 'ICS 43', 'ICS 89', 'ICS 100', 'IMC 67', 'PA 121 [PER]', 'POUND 7 [POU]', 'SCA 6', 'SPA 9 [COL]', 'UF 29', 'UF 613' and 'UF 667'. However, the identification of mislabelled trees should depend ultimately on molecular analysis. Hence, the use of voucher specimens for verification is forwarded and the concept of a public domain database for microsatellite analyses of germplasm holdings is raised.  相似文献   

Survival and spatial fidelity of mouflons: The effect of location,age, and sex     

Ruth?KingEmail author  Stephen?P.?Brooks 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(4):486-513

This article is motivated by a series of data on a population of mouflons (Ovisgmelini) in the Caroux-Espinouse massif and focuses upon discriminating between competing biological hypotheses corresponding to the dependence of any or all of the population parameters upon either sex, location, or age. We show how we can analyze the data using a Bayesian approach, where we are able to take into account prior information obtained via a previous radio-tagging study. We consider the Arnason-Schwarz model together with its submodels to describe the data. Efficiently exploring model space using reversible jump Markov chain Monte Carlo methodology, we are able to calculate model-averaged estimates of parameters of interest, which incorporate both parameter and model uncertainty. In addition, we quantitatively compare different biological hypotheses by calculating their corresponding posterior probabilities. In particular, we show that survival rates tend to remain constant with some evidence to suggest a slight senescent decline. We also provide evidence to suggest that movement around the habitat is largely the same for both sexes up until age 4, when the males appear to extend their migration range, venturing further from the main flock in search of better grazing.  相似文献