Search results for "soil structure"
showing 10 items of 37 documents
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Fire effects on soil aggregation: A review
2011
Abstract Fire can affect soil properties depending on a number of factors including fire severity and soil type. Aggregate stability (AS) refers to soil structure resilience in response to external mechanical forces. Many authors consider soil aggregation to be a parameter reflecting soil health, as it depends on chemical, physical and biological factors. The response of AS to forest fires is complex, since it depends on how fire has affected other related properties such as organic matter content, soil microbiology, water repellency and soil mineralogy. Opinions differ concerning the effect of fire on AS. Some authors have observed a decrease in AS in soils affected by intense wildfire or …
Humic substances along the profile of two Typic Haploxerert
2002
Abstract In Vertisols, organic matter contributes to soil colour by formation of organo-mineral complexes and affects morphological, physico-chemical, biological and biochemical properties. Turbation may affect the chemical and structural composition of the most stabilised fractions of soil organic matter (SOM), i.e., humic substances (HS). The objectives of this study were to: (1) characterise SOM in two Vertisols (V1 and V2) developed under Mediterranean climate in Italy, using some HS characteristics as indicators of SOM turnover in Vertisols, and (2) explore possible differences related to the pedomorphologic conditions of the area under which two soils have formed. SOM evolution along …
A method for the preparation of repacked soil cores with homogeneous aggregates for studying microbial nitrogen transformations under highly controll…
1998
International audience; he feasibility of studies on nitrate transformations during incubation in controlled conditions of air-filled porosity using a method of soil core preparation was investigated. Repacked cores were obtained by uniaxial confined compression in a cylindrical mould of a mass of calibrated and conveniently wet aggregates with a water content selected to saturate the textural porosity of the soil aggregates, imposing structural porosity and thereby producing controlled conditions of aeration. The principle and the descrip- tion of the incubation method are explained and some denitrification and respiration data obtained with low and increasing OZ partial pressures are pres…
Poplar biomass production at phytomanagement sites is significantly enhanced by mycorrhizal inoculation
2017
Abstract Afforestation of trace element (TE)-contaminated soil, notably with fast growing trees producing large biomass has been demonstrated to be an attractive option for their bioremediation. Mycorrhizal fungi can form symbiotic associations with plants, contributing to TE tolerance and participating actively in bioremediation processes. We studied the effects of mycorrhizal inoculation on the growth of two poplar clones (Skado and I214), to large-scale. Two TE-contaminated sites of ca . 1 ha (Pierrelaye and Fresnes-sur-Escaut, France) were planted with 2200 trees, and were either inoculated with a mixed commercial inoculum or not-inoculated and allometric parameters were determined afte…
AlomySys: Modelling black-grass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil …
2006
International audience; Weed emergence models are increasingly necessary to evaluate and design cropping systems. The model AlomySys was developed for a frequent and harmful weed, i.e. Alopecurus myosuroides Huds. [Colbach, N., Dürr, C., Roger-Estrade, J., Caneill, J., 2005a. How to model the effects of farming practices on weed emergence. Weed Res. 45, 2–17; Colbach, N., Dürr, C., Roger-Estrade, J., Chauvel, B., Caneill, J., 2005b. AlomySys: modelling blackgrass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil climate. I. Construction. Eur. J. Agronomy] and is based on sub-models predicting (a) soil environment (climate, s…
Effets du mode de travail du sol sur les microorganismes à l'échelle du profil cultural
2009
Soil tillage modifies the location of crop residues and soil structure and affects microbial populations and activities such as mineralization of soil organic matter. The aim of this work was to compare the effect of two tillage systems (traditional mouldboard ploughing, LT, and reduced tillage, TR) on crop residues distribution and soil structure as well as their consequences on soil microbial biomass (BM), the potential activity of C mineralization (Cmin) and soil bacterial community structure (through T-RFLP). In order to study simultaneously the effects of soil structure modifications and crop residues distribution on these microbial parameters we used a stratified sampling scheme based…
Impacts of thinning of a Mediterranean oak forest on soil properties influencing water infiltration
2017
[EN] In Mediterranean ecosystems, special attention needs to be paid to forest¿water relationships due to water scarcity. In this context, Adaptive Forest Management (AFM) has the objective to establish how forest resources have to be managed with regards to the efficient use of water, which needs maintaining healthy soil properties even after disturbance. The main objective of this investigation was to understand the effect of one of the AFM methods, namely forest thinning, on soil hydraulic properties. At this aim, soil hydraulic characterization was performed on two contiguous Mediterranean oak forest plots, one of them thinned to reduce the forest density from 861 to 414 tree per ha. Th…
Recent Developments in Understanding Biochar’s Physical–Chemistry
2021
Biochar is a porous material obtained by biomass thermal degradation in oxygen-starved conditions. It is nowadays applied in many fields. For instance, it is used to synthesize new materials for environmental remediation, catalysis, animal feeding, adsorbent for smells, etc. In the last decades, biochar has been applied also to soils due to its beneficial effects on soil structure, pH, soil organic carbon content, and stability, and, therefore, soil fertility. In addition, this carbonaceous material shows high chemical stability. Once applied to soil it maintains its nature for centuries. Consequently, it can be considered a sink to store atmospheric carbon dioxide in soils, thereby mitigat…
Soil aggregate stability in three Mediterranean environments
1996
Abstract This paper considers the effect of vegetation on soil aggregate stability in three different Mediterranean landscapes in Southeast Spain. Soils on limestone, marls and clays, with two levels of vegetation cover at each north-facing slopes of the study areas, were investigated. Three aggregate stability tests (CND, TDI and UD) based on the drop impact and ultrasonic dispersion methods and the Emerson dispersion test were performed. The results of the experiments show the positive influence of vegetation on aggregate stability. However, vegetation is less important than lithology in influencing soil aggregate stability. Soil depth and moisture also affect aggregation, but the relatio…