Determination of soil texture: Comparison of the sedimentation method and the laser‐diffraction analysis

Laser‐diffraction analysis (LDA) is a rapid automated method achieving highly resolved frequency distributions of particle sizes. Recently, LDA has come into use in environmental sciences. However, in the size range of silt and clay deviations from the particle‐size analysis with the standard pipette method, which is regarded as the reference method for soil‐texture classification, have been reported. Therefore, this study concentrates (1) on the verification of systematic relations between both methods using a series of soils of Lower Saxony (Germany) and (2) on the general applicability of the laser‐diffraction method to soil‐texture classification as well as (3) texture‐based estimates of air capacity, available field capacity, and permanent wilting point. The comparison of LDA with the pipette method demonstrated highly significant linear correlations in each of the particle‐size fractions from clay to coarse silt. The slope of regressions ranged from 0.4 with fine silt to 3.1 with clay. If the clay content derived from LDA was applied to texture classification, the resulting textural classes differed from the standard textural classes, except for purely sandy samples with a clay content of <5%. However, the linear‐regression model enabled an approach of the LDA‐based clay content to values produced with the standard pipette method. Using this transformation, a texture classification became practicable in many cases, but, despite of a high significance level between LDA and pipette method, still led to wrong textural classes in several cases. A comparison with regression models from other regions in Europe showed both similarities and discrepancies, even for similar substrates. Hence, the laser‐diffraction analysis cannot be used for the texture classification of soil samples without verification by the standard pipette method.     

Methane oxidation,nitrification, and counts of methanotrophic bacteria in soils from a long-term fertilization experiment (”︁Ewiger Roggenbau” at Halle)

Aerobic soils are important sinks for atmospheric methane. CH₄ oxidation, mediated mainly by methanotrophic bacteria, is the responsible process, which is strongly inhibited by ammonium accessible for nitrification. An inhibitory effect immediately after fertilization as well as a long-term effect exists, which results from repeated ammonium applications and which is independent from the actual concentration of NH₄⁺-N in soil. This long-term effect could be caused by a shift in the microbial population of the soil. Thus, with soil samples from long-term fertilization treatments of the field experiment ”︁Ewiger Roggenbau” at Halle (Germany) incubation studies were conducted to investigate the interference between CH₄ oxidation and nitrification and to determine the cell numbers of methanotrophic bacteria. Including the treatments PK, NPK, and farmyard manure, which were established in 1878, a close negative correlation between CH₄ oxidation and net nitrification was found (r = —0.92). The CH₄ oxidation rates, determined with an initial concentration of 10 μl CH₄ l^—1, varied between 6.7 and 1.1 μg C kg^—1 d^—1 in the PK and NPK treatment, respectively. After application of NH₄Cl a strong inhibition of CH₄ oxidation occurred, which was 91%, 88%, 81%, and 63% in the treatments PK, NPK, FYM, and U (unfertilized), respectively. After a lag-phase of 2 to 3 weeks an incubation with high CH₄ concentrations (20 Vol.% CH₄) could induce CH₄ oxidizing activity in the NPK treatments under continuous rye or maize cropping. An increase of up to 40 times in comparison to the control under atmospheric CH₄ (2 μl CH₄ l^—1) was observed. A negative correlation (r = —0.74) existed between the CH₄ oxidation rates of the soils without recently applied NH₄⁺ and the numbers of methanotrophic bacteria, determined with the ”︁most probable number” method (MPN). Thus, the MPN technique is not suitable to characterize the physiologically active population of methanotrophic bacteria in soils, which oxidize CH₄ in the atmospheric concentration range. The results of this study suggest that in aerobic arable soils methanotrophic bacteria and not nitrifiers are responsible for CH₄ oxidation.     

Delineation of management zones with spatial data fusion and belief theory

Precision Agriculture - Precision agriculture, as part of modern agriculture, thrives on an enormously growing amount of information and data for processing and application. The spatial data used...     

Organochlorine residues and shell thicknesses in eggs of the clapper rail, common gallinule, purple gallinule, and limpkin (class Aves), eastern and southern United States, 1972-74

Organochlorine residues and shell thicknesses were surveyed in eggs of the clapper rail (Rallus longirostris), purple gallinule (Porphyrula martinica), common gallinule (Gallinula chloropas), and limpkin (Aramus guarauna) from the eastern and southern United States. Clapper rail eggs were collected during 1972-73 in New Jersey, Virginia, and South Carolina. During 1973-74, gallinule eggs were collected in Florida, South Carolina, and Louisiana, and limpkin eggs were collected in Florida. Egg contents were analyzed for residues of organochlorine pesticides, including DDT, TDE, DDE, dieldrin, mirex, heptachlor epoxide, oxychlordane, cis-chlordane (and/or trans-nonachlor), cis-nonachlor, hexachlorobenzene (HCB), toxaphene, and endrin, and for polychlorinated biphenyls (PCBs). Shell thicknesses of recent eggs of these species were compared with archival eggs that had been collected before 1947. With the exception of the limpkin, the majority of eggs analyzed contained residues of p,p'-DDE and PCBs. Geometric means ranged from 0.10 ppm to 1.3 ppm. Small amounts (less than 1.0 ppm) of mirex, dieldrin, cis-chlordane (and/or trans-nonachlor), TDE, and DDT were detected in a few eggs. No evidence of eggshell thinning was found for any of the species studied. DDE residues in clapper rail eggs were higher in New Jersey and Virginia than in South Carolina.     

Organochlorine residues in young herons from the upper Mississippi River-1976.

Chicks of great blue herons (Ardea herodias) from four heronaries located near South St. Paul, Royalton, and Wabasha, Minnesota, and La Crosse, Wisconsin, were analyzed for organochlorines, Highest mean wet-weight concentrations, 6.43 ppm PCBs. 1.31 ppm DDE, and 1.90 ppm sigma DDT, were found in the South St. Paul chicks. Among chicks from the other three heronries, most levels were similar, but were significantly lower than levels in South St. Paul chicks. Lowest mean organochlorine levels, 0.37 ppm DDE, 0.38 ppm sigma DDT, and 0.22 ppm PCBs, were found in chicks from Royalton. All birds from South St. Paul and La Crosse contained residues of DDT and TDE whereas only one of the 10 birds from Royalton contained DDT and one contained TDE residues. Five of the 12 birds from Wabasha contained DDT; eight contained TDE. Except for PCB residues in La Crosse heron chicks, the rate of organochlorine residue accumulation in the birds was generally less than the rate of dilution caused by growth.     

A randomized, controlled study to evaluate the steroid sparing effect of essential fatty acid supplementation in the treatment of canine atopic dermatitis

A randomized, double blind, placebo-controlled multicentre clinical trial of 12 weeks' duration was undertaken in 60 dogs with atopic dermatitis to evaluate the steroid sparing effect of essential fatty acid supplementation. The dogs were randomly assigned to receive either a combination of borage seed oil and fish oil or a placebo, in addition to prednisolone tablets. All dogs received a standardized basal diet. Owners of the dogs recorded pruritus daily using a 10 cm visual analog scale and the dosage of prednisolone was established based on the pruritus score, according to written instructions. The dosage of prednisolone and the use of any concurrent treatment (shampoo and/or ear-cleanser) were recorded by the owner on a daily basis. The investigators graded the skin lesions at days 0, 42 and 84. The use of prednisolone during the test period was lower in the active group, but the difference was not statistically significant (P = 0.32). The test period was sequentially divided into 43-84, 50-84, 57-84, 64-84, 71-84 and 78-84 days. On day 64, the difference between the active group and the placebo group reached statistical significance (P = 0.04) with an increasing difference towards the end of the study. A statistically significant reduction in the pruritus scores and the total clinical scores from day 0 to day 84 was apparent in both groups (P < 0.0001). At the end of the study, both the pruritus score and the total clinical score were lower in the active group. Our findings indicate a steroid sparing effect of essential fatty acid supplementation in canine atopic dermatitis and, furthermore, that there is a time lag before the effect is attained.     

Effects of desflurane and mode of ventilation on cardiovascular and respiratory functions and clinicopathologic variables in horses

OBJECTIVE: To quantitate the effects of desflurane and mode of ventilation on cardiovascular and respiratory functions and identify changes in selected clinicopathologic variables and serum fluoride values associated with desflurane anesthesia in horses. ANIMALS: 6 healthy adult horses. PROCEDURE: Horses were anesthetized on 2 occasions: first, to determine the minimum alveolar concentration (MAC) of desflurane in O2 and second, to characterize cardiopulmonary and clinicopathologic responses to 1X, 1.5X, and 1.75X desflurane MAC during both controlled and spontaneous ventilation. RESULTS: Mean +/- SEM MAC of desflurane in horses was 8.06 +/- 0.41 %; inhalation of desflurane did not appear to cause airway irritation. During spontaneous ventilation, mean PaCO2 was 69 mm Hg. Arterial blood pressure, stroke volume, and cardiac output decreased as the dose of desflurane increased. Conditions of intermittent positive pressure ventilation and eucapnia resulted in further cardiovascular depression. Horses recovered quickly from anesthesia with little transient or no clinicopathologic evidence of adverse effects. Serum fluoride concentration before and after administration of desflurane was below the limit of detection of 0.05 ppm (2.63microM/L). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that desflurane, like other inhalation anesthetics, causes profound hypoventilation in horses. The magnitude of cardiovascular depression is related to dose and mode of ventilation; cardiovascular depression is less severe at doses of 1X to 1.5X MAC, compared with known effects of other inhalation anesthetics under similar conditions. Desflurane is not metabolized to an important degree and does not appear to prominently influence renal function or hepatic cellular integrity or function.     

Effects of sevoflurane dose and mode of ventilation on cardiopulmonary function and blood biochemical variables in horses

OBJECTIVE: To quantitate effects of dose of sevoflurane and mode of ventilation on cardiovascular and respiratory function in horses and identify changes in serum biochemical values associated with sevoflurane anesthesia. ANIMALS: 6 healthy adult horses. PROCEDURE: Horses were anesthetized twice: first, to determine the minimum alveolar concentration (MAC) of sevoflurane and second, to characterize cardiopulmonary and serum biochemical responses of horses to 1.0, 1.5, and 1.75 MAC multiples of sevoflurane during controlled and spontaneous ventilation. Results-Mean (+/- SEM) MAC of sevoflurane was 2.84 +/- 0.16%. Cardiovascular performance during anesthesia decreased as sevoflurane increased; the magnitude of cardiovascular depression was more severe during mechanical ventilation, compared with spontaneous ventilation. Serum inorganic fluoride concentration increased to a peak of 50.8 +/- 7.1 micromol/L at the end of anesthesia. Serum creatinine concentration and sorbitol dehydrogenase activity reached their greatest values (2.0 +/- 0.8 mg/dL and 10.2 +/- 1.8 U/L, respectively) at 1 hour after anesthesia and then returned to baseline by 1 day after anesthesia. Serum creatine kinase, aspartate aminotransferase, and alkaline phosphatase activities reached peak values by the first (ie, creatine kinase) or second (ie, aspartate aminotransferase and alkaline phosphatase) day after anesthesia. CONCLUSIONS AND CLINICAL RELEVANCE: Sevoflurane causes dose-related cardiopulmonary depression, and mode of ventilation further impacts the magnitude of this depression. Except for serum inorganic fluoride concentration, quantitative alterations in serum biochemical indices of liver- and muscle-cell disruption and kidney function were considered clinically unremarkable and similar to results from comparable studies of other inhalation anesthetics.     

The correlation of potassium content and moisture in bovine liver samples analyzed for trace mineral concentrations.

Beef cattle in the United States are often found to be deficient in essential trace minerals such as copper and zinc. Established reference ranges for mineral concentrations exist and usually designate a concentration as adequate, marginal, deficient, or excessive. This research investigates a new method of interpreting detected elemental concentrations in bovine liver that will add confidence to the final diagnosis. This is based on the hypothesis that a correlation exists between potassium concentration and moisture in a bovine liver sample. This relationship between potassium and moisture content enables the diagnostician to more accurately predict mineral concentrations and wet weight regardless of sample moisture loss. Correlations were found between potassium content and percentage of moisture in experimental samples, clinical biopsies, and a validation study, to a statistical significance of P < 0.001. Experimental samples had a correlation coefficient of R2 = 0.95 and the mathematical relationship y = 2513.2x(-1.0662). Clinical biopsies had a correlation of R2 = 0.83 and the mathematical relationship y = 2203.4x(-0.991). The validation study had a correlation of R2 = 0.55 and a mathematical relationship y = 2321.4x(-0.952). An exponent of -1 is predicted by conservation of potassium mass. These findings have practical significance in maintaining and improving cattle growth, health, reproduction, and food safety.     

Methicillin-resistant Staphylococcus aureus (MRSA) isolated from small and exotic animals at a university hospital during routine microbiological examinations

Clinical specimens of small animals (n=869) were screened for the occurrence of methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA; MRSA) during routine microbiological examinations, and results were confirmed by a multiplex PCR strategy. The genetic relatedness of all mecA-positive S. aureus isolates was further investigated by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), PCR for Panton-Valentine leukocidine genes (PVL) and staphylococcal cassette chromosome mec-typing (SCCmec). A total of 61 S. aureus isolates were found during a 20-month period of investigation, 27 (44.3%) of them harbouring the mecA gene for methicillin-resistance. The majority of MRSA were isolated in specimens from dogs (n=18) and cats (n=4). One guinea pig and one rabbit were found to be positive for an MRSA infected site. Similarly, three exotic animals, a turtle, a bat and a parrot, were found to be infected with MRSA. PFGE and MLST analysis revealed a certain genotype ("A" and "A-1") dominating the isolate collection (23 of 27). Furthermore, one isolate showed homologous PFGE pattern to the German epidemic strain Barnim ("BE") and another one ("BE-1") was considered to be closely related. A third genotype ("B") was detected in two cases. Two different sequence types (ST) were identified among the 27 MRSA isolates. PFGE type "A" and both strains related to the Barnim epidemic strain were assigned to ST22, whereas ST239 was associated to PFGE profile "B". The present data show that certain MRSA genotypes are capable of infecting a wide spectrum of small and exotic animals, especially in clinical facilities.