Search results for "Soil classification"
showing 10 items of 99 documents
Differenziazione e quantificazione dei carbonati litogenici e pedogenici di Gypsisuoli forestali attraverso l'analisi isotopica
2004
Gli autori riferiscono sui tipi e sui modelli di genesi dei carbonati dei suoli, attraverso l’uso degli isotopi del 13C. Lo studio è stato condotto in un’area dell’interno collinare argilloso siciliano, su suoli che evolvono sui depositi evaporitici della Serie Gessoso-Solfifera. Sono stati scelti cinque pedon su litotipi calcarei e non. I pedon sono stati descritti in campo e campionati secondo la sequenza degli orizzonti genetici; sui campioni di suolo sono state eseguite le seguenti analisi: tessitura, reazione, conducibilità elettrica, gesso, carbonio organico ed inorganico. Inoltre, parallelamente sono state eseguite le analisi isotopiche del carbonio organico ed inorganico. I risultat…
Impact of changing forest management on soil organic matter in low mountain acid media
2002
The impacts of changes in vegetation cover from native deciduous forest to Douglas fir ( Pseudotsuga menziesii Franco) and of human activity on soil organic matter (SOM) characteristics were studied in two low mountain areas of east-central France. No striking difference in soil type (Dystric Cambisol) was found between the two sites. Humus-rich horizons were of the “Dysmull” and “Moder” types, regardless of the nature of the bedrock. Contrary to a common affirmation concerning other coniferous species, Douglas fir had no negative effect on soil pH and humification degree of SOM, with respect to the native beech vegetation. Pruning and partial clearing slightly improved humification, espect…
Influence of Initial Water Content on the Wettability of Autoclaved Soils
2010
Autoclaving is a commonly used practice to destroy microbial activity in soils but is thought to have a limited effect on other soil properties. Small changes in chemical composition have been reported, but there have been no previous reports of any alteration of physical properties. This study, however, showed that autoclaving can cause a major change in soil hydraulic properties. For samples with intermediate water contents (10-35% v/v), it caused severe or extreme water repellency in three of four soil types tested, although no effect for initially low or high water contents was found. These findings have important implications for any experimental work involving soil autoclaving as a pr…
Contrasting evolution of iron phase composition in soils exposed to redox fluctuations
2018
Abstract Ferric iron (FeIII) solid phases serve many functions in soils and sediments, which include providing sorption sites for soil organic matter, nutrients, and pollutants. The reactivity of Fe solid phases depends on the mineral structure, including the overall crystallinity. In redox-active soils and sediments, repeated reductive dissolution with subsequent exposure to aqueous ferrous iron (Fe2+) and oxidative re-precipitation can alter Fe phase crystallinity and reactivity. However, the trajectory of Fe mineral transformation under redox fluctuations is unclear and has been reported to result in both increases and decreases in Fe phase crystallinity. Several factors such as water bu…
Comparison of Metrics for the Classification of Soils Under Variable Geometrical Conditions Using Hyperspectral Data
2008
International audience; The objective of this letter is to find a distance metric between reflectance spectra that is not sensitive to the variations on the soil reflectance induced by the geometry of solar-view angles. This is motivated by the fact that differences between spectra measured for the same soil under different observation and illumination configurations can lead to misclassifications. Using 26 soils of different compositions simulated with Hapke’s model and 92 soils of different compositions measured under 28 solarview angle geometries in laboratory conditions, we tested three metrics, namely, root-mean-square error, spectral angle mapper, and R2 (the coefficient of determinat…
Composting rice straw with sewage sludge and compost effects on the soil-plant system.
2008
Composting organic residue is an interesting alternative to recycling waste as the compost obtained may be used as organic fertilizer. This study aims to assess the composting process of rice straw and sewage sludge on a pilot-scale, to evaluate both the quality of the composts obtained and the effects of applying such compost on soil properties and plant development in pot experiments. Two piles, with shredded and non-shredded rice straw, were composted as static piles with passive aeration. Throughout the composting process, a number of parameters were determined, e.g. colour, temperature, moisture, pH, electrical conductivity, organic matter, C/N ratio, humification index, cation exchang…
Direct seeding mulch-based cropping increases both the activity and the abundance of denitrifier communities in a tropical soil
2009
International audience; This study evaluated the impact of direct seeding mulch-based cropping (DMC), as an alternative to conventional tilling (CT), on a functional community involved in N cycling and emission of greenhouse gas nitrous oxide (N2O). The study was carried out for annual soybean/rice crop rotation in the Highlands of Madagascar. The differences between the two soil management strategies (direct seeding with mulched crop residues versus tillage without incorporation of crop residues) were studied along a fertilization gradient (no fertilizer, organic fertilizer, organic plus mineral fertilizers). The activity and size of the denitrifier community were determined by denitrifica…
An assessment of factors controlling N2O and CO2 emissions from crop residues using different measurement approaches
2017
Management of plant residues plays an important role in maintaining soil quality and nutrient availability for plants and microbes. However, there is considerable uncertainty regarding the factors controlling residue decomposition and their effects on greenhouse gas (GHG) emissions from the soil. This uncertainty is created both by the complexity of the processes involved and limitations in the methodologies commonly used to quantify GHG emissions. We therefore investigated the addition of two soil residues (durum wheat and faba bean) with similar C/N ratios but contrasting fibres, lignin and cellulose contents on nutrient dynamics and GHG emission from two contrasting soils: a low-soil org…
Short-term effects of wood ants (Formica aquilonia Yarr.) on soil animal community structure
1999
Abstract Wood ants are known to affect the structure of invertebrate communities in tree canopies but it is not clear whether wood ants can affect the structure of soil animal communities. To isolate the direct effects of wood ants on soil fauna, I manipulated wood ant density in a 6-week mesocosm experiment by placing mesocosms (O 14 cm, height 13.5 cm) permeable to ants either on or outside the ant trails. The mesocosms contained litter, humus, and a diverse soil fauna typical of coniferous forest. I controlled earthworm species composition and biomasses by inoculating 470 mg fresh mass of epigeic lumbricid Dendrobaena octaedra (Sav.) or Dendrodrilus rubidus (Sav.) to the mesocosms. A 15-…
Insights into the effect of soil pH on N(2)O and N(2) emissions and denitrifier community size and activity.
2010
ABSTRACT The objective of this study was to investigate how changes in soil pH affect the N 2 O and N 2 emissions, denitrification activity, and size of a denitrifier community. We established a field experiment, situated in a grassland area, which consisted of three treatments which were repeatedly amended with a KOH solution (alkaline soil), an H 2 SO 4 solution (acidic soil), or water (natural pH soil) over 10 months. At the site, we determined field N 2 O and N 2 emissions using the 15 N gas flux method and collected soil samples for the measurement of potential denitrification activity and quantification of the size of the denitrifying community by quantitative PCR of the narG , napA ,…