Abundance and diversity of soil mites of fragmented habitats in a biosphere reserve in Southern Nigeria

Soil samples were collected from the top 7.5 cm of soil in a Strict Natural Reserve (SNR), a surrounding buffer zone, a cassava farm and matured plantations of Gmelina, teak, and pine, so as to determine if plantation establishment and intensive cultivation affect the density and diversity of soil mites. Altogether, 41 taxonomic groups of mites were identified. The diversity and densities of mites in within the SNR, the buffer zone and the Gmelina were more than the diversity and densities in the cassava farm, teak and pine plantations. Each plantation had its own unique community structure which was different from the community structure in the SNR plot. The SNR plot and Gmelina were dominated by detritivorous cryptostigmatid mites unlike teak and pine which were dominated by predatory mesostigmatid and prostigmatid mites respectively. Low cryptostigmatid mite densities in the plantations and cassava farm were seen as a consequence of low fertility status of the soil, the evidence of which was revealed by soil pH and organic matter data.

Low-cost microprocessed instrument for evaluating soil temperature profile

This paper describes a low-cost microprocessed instrument for in situ evaluating soil temperature profile ranging from -20.0°C to 99.9°C, and recording soil temperature data at eight depths from 2 to 128 cm. Of great importance in agriculture, soil temperature affects plant growth directly, and nutrient uptake as well as indirectly in soil water and gas flow, soil structure and nutrient availability. The developed instrument has potential applications in the soil science, when temperature monitoring is required. Results show that the instrument with its individual sensors guarantees ±0.25°C accuracy and 0.1°C resolution, making possible localized management changes within decision support systems. The instrument, based on complementary metal oxide semiconductor devices as well as thermocouples, operates in either automatic or non-automatic mode.

Monitoring of Finnish arable land : changes in soil quality between 1987 and 1998

Selostus: Suomalaisten viljelymaiden tilan seuranta : muutoksia peltojen ominaisuuksissa aikavälillä 1987-1998

Soil Tracking Paint Test, MLR-89-13, 1989

A new paint testing device was built to determine the resistance of paints to darkening due to road grime being tracked onto them. The device consists of a tire rotating on a sample drum. Soil was applied to the tire and then tracked onto paint samples which were attached to the drum. A colorimeter was used to measure the lightness of the paints after being tracked. Lightness is measured from 0 (absolute black) to 100 (absolute white). Four experiments were run to determine the optimum time length to track a sample, the reproducibility, the effects of different soils, and the maximum acceptable level for darkening of a paint. The following conclusions were reached: 1) the optimum tracking time was 10 minutes; 2) the reproducibility had a standard deviation of 1.5 lightness units; 3) different soils did not have a large effect on the amount of darkening on the paints; 4) a maximum acceptable darkness could not be established based on the limited amount of data; and 5) a correlation exists between the paints which were darkening in the field and the paints which were turning the darkest on the tracking wheel.

Studies on Soil-Aggregate-Sodium Chloride Stabilized Roads in Franklin County, Iowa, HR-33

This investigation was conducted to study the performance characteristics of low cost roadway surfaces of soil-aggregate-sodium chloride mixtures. Many roads have been successfully stabilized with sodium chloride. However, little information is available on either the properties of the road materials or the effects of sodium chloride on the materials. The performance of some of the sodium chloride stabilized roads in Franklin County, Iowa, and the performance of some near-by nonchemically treated roads has been studied. The study of sodium chloride stabilized roads was restricted to the roads in which the binder soil used in construction came from the same source. The effects of sodium chloride on some of the engineering properties of the soil and soil-aggregate mixtures used were studied in the laboratory.

Evaluation of Carbide Waste Lime for Soil Stabilization, Progress Report, HR-111

A lime by-product from the manufacture of acetylene from calcium carbide will be commercially available in Iowa. Since the cost of carbide waste lime f.o.b. source is only about half that of ordinary commercial lime, this material was investigated for potential uses in soil stabilization. The by-product lime is calcium hydroxide in a water slurry with approximately 40% solid concentration. Its effectiveness at stabilizing soils was checked by comparing with commercial high-calcium and dolomitic monohydrate varieties of lime. This was done by soil strength and plasticity tests in addition to studies of the reaction products by X-ray diffraction and chemical methods.

Comparison of citrus rooting evaluation methods using root images in soil profiles and root weight

A digitized image method was compared with a standard washing technique for measuring citrus roots in the field. Video pictures of roots were taken in a soil profile. The profile area analyzed was defined by iron rings, which were also used to remove the roots to determine their dry weight. The roots presented in the pictures were quantified using SIARCS software developed by Embrapa. The root length and area determined by digital images provided a good estimate of root quantity present in the profile.

Diversity and structure of AMF communities as affected by tillage in a temperate soil.

Arbuscular mycorrhizal fungi (AMF) were studied in differently tilled soils from a long-term field experiment in Switzerland. Diversity and structure of AMF communities were surveyed either directly on spores isolated from the field soil or on spores isolated from trap cultures, planted with different host plants. Single-spore cultures were established from the AMF spores obtained from trap cultures. Identification of the AMF was made by observation of spore morphology and confirmed by sequencing of ITS rDNA. At least 17 recognised AMF species were identified in samples from field and/or trap cultures, belonging to five genera of AMF--Glomus, Gigaspora, Scutellospora, Acaulospora, and Entrophospora. Tillage had a significant influence on the sporulation of some species and non- Glomus AMF tended to be more abundant in the no-tilled soil. The community structure of AMF in the field soil was significantly affected by tillage treatment. However, no significant differences in AMF diversity were detected among different soil tillage treatments. AMF community composition in trap cultures was affected much more by the species of the trap plant than by the original tillage treatment of the field soil. The use of trap cultures for fungal diversity estimation in comparison with direct observation of field samples is discussed.

A Study to Correlate Soil Consistency Limits with Soil Moisture Tensions, HR-27, 1965

The liquid and plastic limits of a soil are consistency limits that were arbitrarily chosen by Albert Atterberg in 1911. Their determination is by strictly empirical testing procedures. Except for the development of a liquid limit device and subsequent minor refinements the method has remained basically unchanged for over a half century. The empirical determination of an arbitrary limit would seem to be contrary to the very foundations of scientific procedures. However, the tests are relatively simple and the results are generally acceptable and valuable in almost every conceivable use of soil from an engineering standpoint. Such a great volume of information has been collected and compiled by application of these limits to cohesive soils, that it would be impractical and virtually impossible to replace the tests with a more rational testing method. Nevertheless, many believe that the present method is too time consuming and inconsistent. Research was initiated to investigate the development of a rapid and consistent method by relating the limits to soil moisture tension values determined by porous plate and pressure membrane apparatus. With the moisture tension method, hundreds of samples may be run at one time, operator variability is minimal, results are consistent, and a high degree of correlation to present liquid limit tests is possible.

Variation in soil nutrient concentrations and bulk density within peatland forest sites

Abstract

Soil Erosion Control for Secondary Roads, HR-155

Research project HR-155 was initiated to study soil erosion problems along the secondary road system in Iowa and to find a substitute for straw for the control of soil erosion during the period of seed establishment. Accordingly, six field research sites were established to test the ability of commercial soil conditioners to control soil erosion. The six field research sites were selected on the basis of terrain and type of soil material exposed on the cut-slope areas.

Evaluation of Changes in Productivity Resulting from Removal of Soil for Highway Construction, HR-186, 1981

Borrow areas are created where soil is removed to provide needed fill material for highway and other construction projects. Where these areas are located beyond the highway right-of-way, they must be restored and returned to useful purposes. In Iowa, borrow areas are often developed on agricultural lands and therefore, it is necessary to return them to agricultural uses whenever possible. This research project was established to evaluate the changes in row crop productivity where borrow is removed for highway construction. Secondly, several reclamation techniques were selected to be applied to borrow area research sites and the response of crops to each treatment will be evaluated. All borrow area research sites were selected in 1977 from Iowa Department of Transportation construction plans. The Audubon and Buchanan County sites were completed in the fall of 1977 and May 1978, respectively. Both were used for research in 1978, 1979, and 1980. The two remaining sites in Hamilton and Lee Counties were completed in the fall of 1978 and research was conducted at these sites in 1979, 1980, and 1981. In this report, the 1981 results from the Hamilton and Lee County borrow sites will be presented. Secondly, a summary of the three years of research from each borrow area will be presented along with specific and general conclusions from the research project.

Valganciclovir in adult solid organ transplant recipients: pharmacokinetic and pharmacodynamic characteristics and clinical interpretation of plasma concentration measurements.

Valganciclovir and ganciclovir are widely used for the prevention of cytomegalovirus (CMV) infection in solid organ transplant recipients, with a major impact on patients' morbidity and mortality. Oral valganciclovir, the ester prodrug of ganciclovir, has been developed to enhance the oral bioavailability of ganciclovir. It crosses the gastrointestinal barrier through peptide transporters and is then hydrolysed into ganciclovir. This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of this agent, and to address the issue of therapeutic drug monitoring. Based on currently available literature, ganciclovir pharmacokinetics in adult solid organ transplant recipients receiving oral valganciclovir are characterized by bioavailability of 66 +/- 10% (mean +/- SD), a maximum plasma concentration of 3.1 +/- 0.8 mg/L after a dose of 450 mg and of 6.6 +/- 1.9 mg/L after a dose of 900 mg, a time to reach the maximum plasma concentration of 3.0 +/- 1.0 hours, area under the plasma concentration-time curve values of 29.1 +/- 5.3 mg.h/L and 51.9 +/- 18.3 mg.h/L (after 450 mg and 900 mg, respectively), apparent clearance of 12.4 +/- 3.8 L/h, an elimination half-life of 5.3 +/- 1.5 hours and an apparent terminal volume of distribution of 101 +/- 36 L. The apparent clearance is highly correlated with renal function, hence the dosage needs to be adjusted in proportion to the glomerular filtration rate. Unexplained interpatient variability is limited (18% in apparent clearance and 28% in the apparent central volume of distribution). There is no indication of erratic or limited absorption in given subgroups of patients; however, this may be of concern in patients with severe malabsorption. The in vitro pharmacodynamics of ganciclovir reveal a mean concentration producing 50% inhibition (IC(50)) among CMV clinical strains of 0.7 mg/L (range 0.2-1.9 mg/L). Systemic exposure of ganciclovir appears to be moderately correlated with clinical antiviral activity and haematotoxicity during CMV prophylaxis in high-risk transplant recipients. Low ganciclovir plasma concentrations have been associated with treatment failure and high concentrations with haematotoxicity and neurotoxicity, but no formal therapeutic or toxic ranges have been validated. The pharmacokinetic parameters of ganciclovir after valganciclovir administration (bioavailability, apparent clearance and volume of distribution) are fairly predictable in adult transplant patients, with little interpatient variability beyond the effect of renal function and bodyweight. Thus ganciclovir exposure can probably be controlled with sufficient accuracy by thorough valganciclovir dosage adjustment according to patient characteristics. In addition, the therapeutic margin of ganciclovir is loosely defined. The usefulness of systematic therapeutic drug monitoring in adult transplant patients therefore appears questionable; however, studies are still needed to extend knowledge to particular subgroups of patients or dosage regimens.