Search results for "soil water"
showing 10 items of 840 documents
Changes in soil microbial activity and physicochemical properties in agricultural soils in Eastern Spain
2015
Agricultural land management greatly affects soil properties. Microbial soil communities are the most sensitive and rapid indicators of perturbations in land use and soil enzyme activities are sensitive biological indicators of the effects of soil management practices. Citrus orchards frequently have degraded soils and this paper evaluates how land management in citrus orchards can improve soil quality. A field experiment was performed in an orchard of orange trees (<em>Citrus Sinensis</em>) in the Alcoleja Experimental Station (Eastern Spain) with clay-loam agricultural soils to assess the long-term effects of herbicides with inorganic fertilizers (H), intensive ploughing and i…
Selenium Partitioning and Stable Isotope Ratios in Urban Topsoils
2011
oxides. Th e δ82/76 Se values of total Se in the topsoils were close to the bulk Earth composition with an average δ82/76 Se value of −0.03 ± SD 0.38‰ suggesting that there was no or little Se isotope fractionation in soil. We attribute the small isotope fractionation to the low bioavailability of Se as a consequence of the presence of Fe oxides (adsorbing the dominating Se(IV) forms strongly), organic matter, and SO 4 2− (prevents biouptake of the Se(IV) forms) in the study soils. Small Se isotope fractionations of −0.59 to −0.35‰ in mainly forest soils and of 0.26 to 0.45‰ in mainly alluvial soils were presumably caused by soil/plant-recycling and Se contamination by river water, respecti…
Effect of climate and vegetation on soil organic carbon, humus fractions, allophanes, imogolite, kaolinite, and oxyhydroxides in volcanic soils of Et…
2007
A soil sequence along an elevational gradient ranging from subtropical to subalpine climate zones in the Etna region (Sicily, southern Italy) was investigated with respect to organic C, kaolinite, and crystalline to noncrystalline Al and Fe phases. Special emphasis was given to the stabilization of soil organic carbon (SOC) and its interaction with the inorganic phases. The soils were variations of Vitric Andosols that developed on a trachy-basaltic lava flow with an age of 15,000 years. Two main vegetation systems dominated the sites: at the lower sites, it was mainly maquis vegetation and, at the higher elevated sites, predominantly coniferous forest. The concentration of SOC in the topso…
Sur la présence de matières organiques mésocénozoïques dans des humus actuels (bassin de Chaillexon, Doubs, France)
1998
Abstract The optical analysis in the Chaillexon watershed (Doubs, France), of the present soils' humus layers' organic matter points out the contribution of Meso-Cenozoic organic matter in addition to the one produced by vegetal cover. Their relative occurrence varies in each layer: in the reverse of that of vegetal organic matter, the relative amount of Meso-Cenozoic organic matter increases according to the depth. That result shows that the total organic matter amounts in soils (and its evaluation) do not only depend on the net primary production and that geological formations have to be taken into account. Moreover, it suggests that present and past detrital supplies are concerned with ‘…
The influence of weathering processes on labile and stable organic matter in Mediterranean volcanic soils
2008
The relationship and mechanisms among weathering processes, cation fluxes, clay mineralogy, organic matter composition and stability were studied in soils developing on basaltic material in southern Italy (Sicily). The soils were transitions between Phaeozems and Vertisols. Intense losses of the elements Na, Ca and Mg were measured indicating that weathering has occurred over a long period of time. The main weathering processes followed the sequence: amphibole, mica, volcanic glass or if ash was the primary source→smectite→interstratified smectite–kaolinite→kaolinite. Kaolinite formation was strongly related to high Al, Mg and Na losses. The good correlation between oxyhydroxides and kaolin…
Responses of two earthworm populations with different exposure histories to chlorophenol contamination
1998
Two populations of the earthworm Aporrectodea tuberculata (Eisen), one from a chlorophenol contaminated and another from an uncontaminated site in central Finland, were exposed to acute, toxic, and sublethal concentrations of pentachlorophenol (PCP). Exposure history seemed to have only slight effect on the responses of the earthworms. Values of a lethal concentration of 50% in the humus-rich soil were very high, 1,870 μg PCP per gram for the earthworms from the contaminated site and 1,520 μg/g for the earthworms from the uncontaminated site. No differences in the accumulation of PCP from the soil into the earthworms between the two populations were found. Earthworms from both populations s…
Relationships among soil characteristics, plant macronutrients, and cardenolide accumulation in natural populations of Digitalis obscura
2005
In the present study, we have investigated relationships among several soil parameters (pH, organic matter, total carbonate, macronutrients, electrical conductivity, cation-exchange capacity) and macronutrient and cardenolide contents in leaves of wild Digitalis obscura plants. Young and mature leaves and soil samples were collected in ten different areas, corresponding to three Mediterranean bioclimatic belts (thermo-, meso-, and supramediterranean belts). Soil and leaf macronutrient (N, P, K, Ca, and Mg) contents and leaf cardenolide contents were determined. Bioclimatic conditions influenced the development of D. obscura, biomass being lowest in plant populations of the supramediterranea…
Patterns of earthworm, enchytraeid and nematode diversity and community structure in urban soils of different ages
2016
Annelids (Lumbricidae and Enchytraeidae) and nematodes are common soil organisms and play important roles in organic matter decomposition, nutrient cycling and creation of soil structure and porosity. However, these three groups have rarely been studied together and only few studies exist for urban soils. We studied the diversity and community composition of annelids and nematodes in soils spanning more than two centuries of urban soil development in Neuchâtel (Switzerland) and assessed the relationships 1) among these three groups and 2) between each group and environmental (physical, chemical and functional) characteristics of soils and soil age. While the groups of environmental variable…
The Influence of Biomass Ash on the Migration of Heavy Metals in the Flooded Soil Profile - Model Experiment
2014
Soils that have been exposed to fl ood waters can be heavily polluted by inorganic and organic compounds. They are mainly compounds which appear in dissolved or suspended form fl owing together with heavily laden fl oodwater, as well as compounds created as a result of reactions in the soil profi le, mostly due to anaerobic transformation of organic matter. Heavy metals brought with fl ood waters are absorbed by the soil and also washed out from fl ood sediments by precipitation when the fl ood recedes. This paper presents the results of research on the effects of fertilization with ash from incineration or pyrolysis of biomass on the migration process of heavy metals (Zn, Cu, Cr, Ni, Pb, C…
Repelencia al agua en suelos forestales afectados por incendios y en suelos agrícolas bajo distintos manejos y abandono
2013
Soil water repellency determines the water available in the soil system, the runoff generation and the geomorphologic processes. This study examines the soil wettability during the summer of 2008 and 2009 in forest soils with different fire history, and in agricultural soils with different managements. Water repellency was assessed using the Water Drop Penetration Time test (WDPT). Results indicate that water repellency is more frequent and persistent in forest soils than in agricultural ones. In the former, water repellency is reduced a year after a fire and is not recovered during at least 12 years. In agricultural soils, it is found under no till treatment, whereas sites treated with her…