575 research outputs found
Spectrophotometric methods for the measurement of soil pH: A reappraisal
No full textThe pH of aqueous soil extracts is generallymeasured potentiometrically by glass electrode (GE). Spectrophotometric
methods have also been used till around the '80s, and then they have apparently been abandoned. However,
the use of microplates and spectrophotometers able to read absorbance values in them can significantly
increase the speed of the data collection (saving analysis time), thus justifying their reappraisal. Three spectrophotometric
methods are proposed in this work: a one-indicator (OISM), a separated three-indicator (STISM)
and a mixed three-indicator (MTISM) spectrophotometric method. They are based on the addition of one or
three colorimetric indicators (methyl red, bromocresol violet, and bromothymol blue) to the aqueous extract.
The pHismeasured through its absorption properties in the visible region. The analysis of 60 soil samples showed
that STISMand MTISMresults correlate well with the ones obtained by GE. The STISMmethod, beingmore simple
and general than the other two methods, is proposed for quick routine analyses. The repeatability, reproducibility
and accuracy of STISM(and of GE, for comparison)were evaluated bymeasuring several times the pH of a
series of soil samples and of a certified reference soil. The standard deviations of STISM results were slightly
worse than those of GE,whereas the accuracywas slightly better, indicating that STISMand GE have overall similar
performances. STISM method is much faster than GE one: the analysis time saving is around 2 min per sample,
and it becomes very high when hundreds of samples have to be analysed. It follows that STISM can represent
an advantageous alternative to GE for rapid and accurate soil pH measurements
Nutrizione azotata della vite: risultati preliminari dell’applicazione di fertilizzanti organici
No full textDevelopment of a Soil Health Index based on the ecological soil functions for organic carbon stabilization with application to alluvial soils of northeastern Italy.
No full textThere is a need to assess soil health quantitatively to assist with sustainable soil management in agroecosystems. The objective of this research was to develop a farm- level soil health index (SHI) to help identify the most sustainable management practices including C sequestration and agroecosystem resilience to climate change. For all indexing phases we used the Soil Management Assessment Framework. The SHI was created using a minimum data set (MDS) of physical, chemical and biochemical soil indicators chosen via expert opinion (EO-MDS) (24 indicators) and via the results of PCA (PCA-MDS) (16 indicators). Each observed value was converted into a score (0 to 1) by using site-specific non-linear scoring algorithms. Indicator scores were incorporated into a composite SHI which quantified the ecological performance of 5 soil functions: habitat and biodiversity, water movement and availability, filtering and buffering, nutrient cycling, physical stability and support, and long-term C stabilization. For both MDS evaluations, we assessed agroecosystems managed organically (OS) or conventionally (CS). Results from our study showed that OS had significantly higher (P< 0.05) SHI scores compared to the CS. SHI, with EO-MDS, was more efficient (P=0.028) than the PCA-MDS (P=0.039) when determining the effect of soil management practices on soil health. Non-linear transformation was a useful technique and represented soil ecological functionality effectively. Five out of six soil functions had significantly greater (P< 0.05) ecosystem performance in OS compared to CS, except for water movement and availability. The benefit for OS lead to a greater soil health status, allowing the system to be more resilient to climate change, to efficiently provide nutrients to plants, and to sustain an active soil food web for the long-term stabilization of C. The SHI may help optimize and provide extensive insight into all aspects of soil health which are intricately linked to soil-based ecological functions at the farm level
The Spatial Representation of Angles
No full textWe investigated whether angle magnitude, similarly to numerical quantities\ud
(i.e., the spatial-numerical association of response codes effect),\ud
is associated to the side of response execution.\ud
In addition, we investigated whether this association has the properties of a spatially oriented mental line,\ud
since angles are taught in a right-to-left progression.\ud
We tested two groups of participants: civil engineering students\ud
(high familiarity with angles) and psychology students (low familiarity with angles).\ud
In Experiment 1, participants were asked to judge the continuity of the angles’ arms (continuous vs. dashed).\ud
Magnitude of the angles was task-irrelevant.\ud
In Experiment 2, they were asked to judge whether the presented angles were smaller or larger than a right angle (90°).\ud
Therefore, the angle magnitude was relevant for performing the task.\ud
Overall, engineering students responded faster with their left hand to large angles and\ud
with their right hand to small angles.\ud
Conversely, psychology students did not show any reliable differences between left- and right-hand responses.\ud
In the case of engineering students, the spatial association has a right-to-left (counter clockwise) direction,\ud
suggesting the influence of education and practice on the mental representation of angle magnitude
Interactions of prion proteins with soil
No full textPrions, are proteinaceous particles recognized as the agents of a class of neurodegenerative disorders, called transmissible spongiform
encephalopathies (TSE), or prion diseases. Epidemiological data suggest that TSE-contaminated environments may serve as source of
infectivity, but there is no information about adsorption of prions onto soil. We carried out experiments by mixing, healthy, or scrapieinfected hamster brains homogenates with three types of soil suspended in different buffers: (i) two saline buffers, i.e., phosphate buffer
solution (PBS) and CaCl2
solution; (ii) a mix of nondenaturing detergents, i.e., Triton X-100 and sodium deoxycholate (DOC) solution;
(iii) a non-ionic detergent, i.e., lauryl maltoside; (iv) two anionic detergents, i.e., Sarkosyl or sodium dodecyl sulphate (SDS); and (v) a
chaotropic agent, i.e., urea. The unbound prion proteins were detected in the supernatants (after centrifugation of soil suspension) by
Western blotting. Results clearly demonstrate that both the no infectious (PrP
C
) and infectious (PrP
Sc
) forms are adsorbed by all soils.
Only 1% sodium dodecylsulphate (SDS) partially impeded the association of PrP
C
, but not that of PrP
Sc
with the sandy loam soil.
Agents with different interacting properties towards hydrophilic and/or hydrophobic domains failed to extract PrP
Sc
from sediments of
soil–brain homogenate mixtures. The strong interaction of PrP
Sc
with soil favors the accumulation of prions in soils, especially if
amended with prion-containing organic fertilizers and/or whenever TSE-affected animal carcasses, placenta, and excreta in general are
buried or laid at the soil surface
Sensitive monitoring of soil fertility in the Valpolicella Valley by the “Fertimetro” tool and a high-throughput enzyme method
No full text
El Tlacuache Núm. 365 (2009). 365 Año 9 (2009) mayo. El Tlacuache
No full textRubén Jaramillo: las intenciones del crimen por Aura Hernández. - Jaramillo y la disputa el sentido de la vida por Flavio Barbosa. - De campesinos a obreros: una comunidad surgida entre las flores por Rafael Gutiérrez
Soil fertility assessment on inter-seeded wheat crop in conservative agriculture by the fertimetro tool and high-throughput enzyme method
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