Search results for "soil"

Effectiveness the source of nitrogen from NO3 and NH4 for Panicum maximum Jacq. growth in saline soil

2019

Abstract The purpose of this study was to determine the source of nitrogen used by Panicum maximum Jacq. plants in salt soil. Experimenting pots in a greenhouse with a medium of saline soil. The 2 × 3 factorial design is used in repeated trials. The first factor is calcium sulfate (0 and 2 t ha−1), the second factor is N fertilizer includes (a) without nitrogen = N0, (b) 60 kg N of potassium nitrate (KNO3) and (c) 60 kg N of ammonium sulfate (NH4SO4). The parameters observed were nitrogen uptake, constant growth rate (CGR), biomass yield, crude protein content, NDF, and ADF. The interaction of calcium sulfate and nitrate fertilizer increases CGR, biomass yield, N, CP and NDF uptake. Interac…

Sub- and supercritical fluid extraction of trichloropyridinol from soil prior to immunoassay

1997

A comparative study on the extraction of TCP (3,5,6-trichloro-2-pyridinol, a metabolite of chlorpyrifos) from soil with CO2 and H2O is reported. The polarity of the analyte requires the presence of both a cosolvent (methanol) and an ion-pair reagent [(1R)-(-)-10-camphorsulfonic acid ammonium salt] for 95% extraction in 30 min when supercritical CO2 at 40 degrees C and 383 bar is used as extractant. Subcritical water (250 degrees C and 200 bar) enables complete extraction within 15 min without additives. Quantitation of the target analyte is performed by specific immunoassay using a non-commercial monoclonal antibody which provides a linear determination range between 0.005 and 5 micrograms/…

Comparison of Three Techniques for Lipid Removal from Seal Blubber: Gel Permeation, Acid Treatment, and Dialysis with Semipermeable Membrane

2000

Abstract Harbor seal blubber samples were analyzed for PCDD/Fs and PCBs by splitting the initial extract into three aliquots and applying three different techniques for lipid removal (the first step of sample cleanup methodology for GC-HRMS analysis): gel permeation chromatography (GPC), sulfuric acid treatment, and dialysis through semipermeable membrane. Correlation coefficients of analyte concentrations obtained from three sets of replicate samples ranged from 0.965 to 0.994. In addition, a number of seal blubber samples were processed without pre-extraction using only the dialysis technique. The analyte concentrations in these samples correlated well with the analyte concentrations obta…

Headspace–mass spectrometry determination of benzene, toluene and the mixture of ethylbenzene and xylene isomers in soil samples using chemometrics

2007

A simple and fast method has been developed for the determination of benzene, toluene and the mixture of ethylbenzene and xylene isomers (BTEX) in soils. Samples were introduced in 10 mL standard glass vials of a headspace (HS) autosampler together with 150 microL of 2,6,10,14-tetramethylpentadecane, heated at 90 degrees C for 10 min and introduced in the mass spectrometer by using a transfer line heated at 250 degrees C as interface. The volatile fraction of samples was directly introduced into the source of the mass spectrometer which was scanned from m/z 75 to 110. A partial least squares (PLS) multivariate calibration approach based on a classical 3(3) calibration model was build with m…

Hookworm-like eggs in children’s faecal samples from a rural area of Rwanda

2016

Background: Hookworm eggs identification and quantification is usually carried out by Kato-Katz method. However various structures present in the smear may be confused with eggs of such parasites. Objective: To document the presence of structures in Kato-Katz slides that could initially be misinterpreted as hookworm eggs. Method: 497 faecal samples were analysed by Kato-Katz technique, diphasic concentration technique, agar-plate coprocultive and larvae obtained were analysed by PCR and characterized by sequencing. Result: Hookworm-like eggs were found in 159 (32%) of the samples by Kato Katz, finally identified as Caenorhabditis elegans by PCR technique. Conclusion: The diagnosis of human …

Effect of laboratory procedures on the integrity of a sandy-loam soil sample for bi-directional measurement of saturated hydraulic conductivity

2011

Practical and validated methods to measure anisotropy of saturated, Ks, or field-saturated, Kfs, soil hydraulic conductivity on a single soil sample are still lacking. The objective of this investigation was to test factors affecting anisotropy measured in a sandy-loam soil by the constant-head laboratory permeameter and the modified cube method. The ratio, RK, between the conductivity results obtained with a long (6 h) and a short (0.5 h) duration run varied from a minimum of 0.29 to a maximum of 0.88 with the considered experimental procedure, differing by both the employed constant-head device (Mariotte bottle, siphon) and the initial soil water content (unsaturated, saturated). Maximum …

Predicting maximum annual values of event soil loss by USLE-type models

2017

Abstract Previous experimental investigations showed that a large proportion of total plot soil erosion over a long time period is generally due to relatively few, large storms. Consequently, erosion models able to accurately predict the highest plot soil loss values have practical importance since they could allow to improve the design of soil conservation practices in an area of interest. At present USLE-based models are attractive from a practical point of view, since the input data are generally easy to obtain. The USLE was developed with specific reference to the mean annual temporal scale but it was also applied at the event scale. Other models, such as the USLE-M and the USLE-MM, app…

Exploiting historical rainfall and landslide data in a spatial database for the derivation of critical rainfall thresholds

2017

Critical rainfall thresholds for landslides are powerful tools for preventing landslide hazard. The thresholds are commonly estimated empirically starting from rainfall events that triggered landslides in the past. The creation of the appropriate rainfall–landslide database is one of the main efforts in this approach. In fact, an accurate agreement between the landslide and rainfall information, in terms of location and timing, is essential in order to correctly estimate the rainfall–landslide relationships. A further issue is taking into account the average moisture conditions prior the triggering event, which reasonably may be crucial in determining the sufficient amount of precipitation.…

Anthropedogenesis and Land Use Change: influences on soil qualities and functions.

2014

Aspects of soil phenolic matter (SPM): An explorative investigation in agricultural, agroforestry, and wood ecosystems

2014

Abstract This paper assesses the distribution of soil phenolic matter (SPM) in soil environments from a pedological perspective, with particular emphasis on soil horizonation and its involvement in pedogenic processes. The study was conducted on 15 soil profiles (Andosols, Calcisols, Cambisols, Lixisols, Phaeozems, Podzols, Umbrisols) covering five distinct ecosystems. Although the ecosystems were virtually homogeneous in and of themselves, they represented strongly contrasting climates, geolithology and morphology, land use and vegetation cover (intensive agriculture, chestnut grove, alpine pasture, woody reforestations, and natural woods). Three main SPM fractions were categorised: (i) “t…