189 research outputs found
Mapping of penetrometer resistance in relation to tractor traffic using multivariate geostatistics
The traffic of agricultural machines can cause soil compaction and high variability of soil structure, both along normal lines and along those parallel to the field plane. The aim of this research is to investigate the potential of geostatistical techniques for understanding and evaluating the within-field spatial variability of soil compaction, caused by the traffic of agricultural machines and/or the action of tillage implements.
In July 2003 soil cone penetrometer resistance was measured in a sandy-silt Cambisol of inland Sicily, where a three-year rotation wheat (Triticum durum Desf.) - wheat - tomato (Solanum lycopersicum L.) was adopted, along three parallel 3-m long transects, from the soil surface to a depth of 0.70 m.
A multivariate geostatistical approach, including exploratory analysis, variography, stochastic simulation and post-processing of simulations was applied to produce thematic maps of penetrometer resistance and probability maps exceeding a critical value, corresponding to different examples of tractor movement. Penetrometer resistance variation was erratic at the surface but showed high spatial correlation between data measured at different depths. The maps of probabilistic compaction risk showed that the soil volume, exceeding the penetrometer resistance of 2.5 MPa, critical for root growth, increased from 20% to 40% after the tractor had passed through five times
An approach for assessing the effects of site-specific fertilization on crop growth and yield of durum wheat in organic agriculture
Semi-Automatic Method for Early Detection of Xylella fastidiosa in Olive Trees Using UAV Multispectral Imagery and Geostatistical-Discriminant Analysis
Xylella fastidiosa subsp. pauca (Xfp) is one of the most dangerous plant pathogens in the world. Identified in 2013 in olive trees in south–eastern Italy, it is spreading to the Mediterranean countries. The bacterium is transmitted by insects that feed on sap, and causes rapid wilting in olive trees. The paper explores the use of Unmanned Aerial Vehicle (UAV) in combination with a multispectral radiometer for early detection of infection. The study was carried out in three olive groves in the Apulia region (Italy) and involved four drone flights from 2017 to 2019. To classify Xfp severity level in olive trees at an early stage, a combined method of geostatistics and discriminant analysis was implemented. The results of cross-validation for the non-parametric classification method were of overall accuracy = 0.69, mean error rate = 0.31, and for the early detection class of accuracy 0.77 and misclassification probability 0.23. The results are promising and encourage the application of UAV technology for the early detection of Xfp infection
Enantiomeric profiling of quinolones and quinolones resistance gene qnrS in European wastewaters
Comparison of phosphodiesterase type V inhibitors use in eight European cities through analysis of urban wastewater
Comparison of phosphodiesterase type V inhibitors use in eight European cities through analysis of urban wastewater
In this work a step forward in investigating the use of prescription drugs, namely erectile dysfunction products, at European level was taken by applying the wastewater-based epidemiology approach. 24-h composite samples of untreated wastewater were collected at the entrance of eight wastewater treatment plants serving the catchment within the cities of Bristol, Brussels, Castellón, Copenhagen, Milan, Oslo, Utrecht and Zurich. A validated analytical procedure with direct injection of filtered aliquots by liquid chromatography-tandem mass spectrometry was applied. The target list included the three active pharmaceutical ingredients (sildenafil, tadalafil and vardenafil) together with (bio)transformation products and other analogues. Only sildenafil and its two human urinary metabolites desmethyl- and desethylsildenafil were detected in the samples with concentrations reaching 60 ng L−1. The concentrations were transformed into normalized measured loads and the estimated actual consumption of sildenafil was back-calculated from these loads. In addition, national prescription data from five countries was gathered in the form of the number of prescribed daily doses and transformed into predicted loads for comparison. This comparison resulted in the evidence of a different spatial trend across Europe. In Utrecht and Brussels, prescription data could only partly explain the total amount found in wastewater; whereas in Bristol, the comparison was in agreement; and in Milan and Oslo a lower amount was found in wastewater than expected from the prescription data. This study illustrates the potential of wastewater-based epidemiology to investigate the use of counterfeit medication and rogue online pharmacy sales
Functionally Important Amino Acids in the Arabidopsis Thylakoid Phosphate Transporter: Homology Modeling and Site-Directed Mutagenesisâ€
Evaluation of metals that are potentially toxic to agricultural surface soils, using statistical analysis, in northwestern Saudi Arabia
© 2015, Springer-Verlag Berlin Heidelberg. Heavy metals in agricultural soils enter the food chain when taken up by plants. The main purpose of this work is to determine metal contamination in agricultural farms in northwestern Saudi Arabia. Fifty surface soil samples were collected from agricultural areas. The study focuses on the geochemical behavior of As, Cd, Co, Cr, Cu, Hg, Pb and Zn, and determines the enrichment factor and geoaccumulation index. Multivariate statistical analysis, including principle component analysis and cluster analysis, is also applied to the acquired data. The study shows considerable variation in the concentrations of the analyzed metals in the studied soil samples. This variation in concentration is attributed to the intensity of agricultural activities and, possibly, to nearby fossil fuel combustion activities, as well as to traffic flows from highways and local roads. Multivariate analysis suggests that As, Cd, Hg and Pb are associated with anthropogenic activities, whereas Co, Cr, Cu and Zn are mainly controlled by geogenic activities. Hg and Pb show the maximum concentration in the analyzed samples as compared to the background concentration
Spatio-temporal assessment of illicit drug use at large scale: evidence from 7 years of international wastewater monitoring
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