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Sofia, Bulgaria

Djokic L.,University of Belgrade | Narancic T.,University of Belgrade | Biocanin M.,University of Belgrade | Saljnikov E.,Institute of Soil Science | And 3 more authors.
Applied Soil Ecology | Year: 2013

Biodegradation of phenol in four natural soils (loamy sand, sandy loam, sandy clay loam and loam) by indigenous microorganisms and in soils augmented by the Bacillus sp. PS11 was studied. During the laboratory soil microcosm experiments, the total removal of 2g of phenol per kg of soil was achieved in all soil types in between 6 and 21 days. All biodegradation data was found to fit very well to saturation kinetics. The most efficient phenol removal was observed in the loamy woodland soil that contained the least amount of sand (42.5%) and the most silt and clay fraction (57.5%) in comparison to other three soil samples. However, amending sandy loam sample to contain more clay (from 13.5% to 30%) negatively affected the phenol removal rate, while increasing sand content (from 74.4% to 90%) resulted in the two times faster phenol removal in comparison to natural soil type. Bacillus sp. PS11 performed well in both pure culture and in the presence of soil microorganisms. Indigenous bacteria from sandy clay loam soil type possessed the ability of phenol bioremediation and almost whole amount of added phenol (2gkgsoil-1) was degraded within 9 days, whereas augmentation by Bacillus sp. PS11 improved the phenol removal by 20%. Carrying out small scale soil model experiments and amending soil granulometric properties by addition of clay or sand minerals is suggested as an effective and economically interesting way of enhancing bacterial soil bioremediation. © 2013 Elsevier B.V.

Vatchev T.D.,Institute of Soil Science
Bulgarian Journal of Agricultural Science | Year: 2015

Fusarium root and stem rot is one of the most damaging diseases of greenhouse cucumber. This study reveals development and spread of airborne inoculum of Fusarium oxysporum f. sp. radicis-cucumerinum the causal agent of the disease. Infective propagules of the pathogen were trapped from the air and recovered from greenhouse interior structures and equipment, including concrete floors, paths and stumps, iron scaffolding components, glass walls, roof surfaces, plastic pots and planters. The results suggest possible reinfestation of freshly steamed or fumigated soils by airborne propagules of the pathogen. © 2015, National Centre for Agrarian Sciences. All rights reserved.

Badea E.M.,Institute of Biochemistry | Chelu F.,Institute of Biochemistry | Lacatusu A.,Institute of Soil Science
Romanian Biotechnological Letters | Year: 2010

Since the introduction of insect-resistant crops in 1996, cultivation of this group of genetically modified crops has grown substantially. There are many Bt corn events in field trials, but only one is commercialized on the Romanian market. The levels of the protein in plant tissue would be valuable in determining the protein concentration to which nontarget organisms may be exposed. The soil fate of the Bt protein is a key parameter governing exposure of nontarget organisms in this environment. The objectives of our study were: (i) to investigate the impact of the soil type on Bt expression levels in transgenic corn tissue (leaves, roots seed); (ii) to monitor the time-dependent degradation of the cry1Ab protein in three soil types favorable for corn growing, with different physicochemical characteristics. Detection and quantification of Cry1Ab protein in tissue (leaves, roots and seeds) and soil extracts was conducted using ELISA method with a commercially available test system for detecting Cry1Ab/Cry1Ac proteins (QuantiPlate Kit for Cry1Ab/Cry1Ac; Agdia), following the recommended protocol of the manufacturer. To evaluate the potential of Bacillus thuringiensis (Bt) Cry1Ab protein accumulation in soil, transgenic corn containing event MON 810 encoding the cry1Ab gene was grown in greenhouse conditions in pots containing three types of soil. At the end of growing period, the corn plants were incorporated into the soil. During vegetative period and at different time points after biomass incorporation, soil samples were collected from pots, and the level of Cry1Ab protein in these samples was determined using ELISA assay. Regarding Bt protein content, there is no difference between plants grown in different soils types. The lowest Bt protein content was quantified in senescent tissue and in seeds. The average chart for test soils shows an initial Bt protein increase after incorporating the plant biomass into the greenhouse soil pots, with the Cry1Ab concentration peaking at about 6-9 weeks after incorporation, and declining slowly towards the 12-15 week (3-4 months) sampling interval. Overall, our results supports the conclusion that the Cry1Ab protein does not persist or accumulate in soil after incorporation in the soil of Bt corn plants expressing this protein. © 2010 University of Bucharest.

Wrobel S.,Institute of Soil Science
Fresenius Environmental Bulletin | Year: 2010

A vegetation experiment was set up to assess the effect of peat and vermicompost used separately or in combination with CaCO3 as soil amendments reducing the availability of excessive amounts of zinc in light soil cropped with sunflower. The best results were attained when vermicompost was added to soil at a rate of 1.5% soil weight along with CaCO3 according to double hydrolytic acidity. With this treatment it was possible to recover 70 to 94% of yields relative to natural (unpolluted) soil, in accordance with the degree of soil pollution with zinc. Peat was the most effective in soil enriching with organic matter. However, its acidifying properties retarded sorption of soluble zinc in soil. Similar concentrations of zinc were determined in aerial parts and roots of sunflower plants, which tended to rise as the zinc pollution rate increased. The results seem to indicate that soil assays employing 1 mol HCl dm-3 can be used for diagnosing zinc pollution in light soil. © by PSP.

Perovic V.,Institute of Soil Science | Zivotic L.,University of Belgrade | Kadovic R.,University of Belgrade | Dordevic A.,University of Belgrade | And 3 more authors.
Environmental Earth Sciences | Year: 2013

This work aims at the assessment of soil erosion rate and its spatial distribution in hilly mountainous Nisava River Basin (South-eastern Serbia) with a surface area of approximately 2,848 km2. The study was conducted using Universal Soil Loss Equation (USLE) model due to its modest data demand and easy comprehensible structure. The erosion factors of USLE were collected and processed through a GIS-based approach. Landsat 7 Enhanced Thematic Mapper (ETM+) image and normalized difference vegetation index (NDVI) were used for the determination of crop management factor. The average annual soil loss was estimated at 27.0 t ha-1 year-1 classifying Nisava River Basin under very high erosion rate category. About 39.0 % of the watershed area was characterized by slight erosion rate (<5 t ha-1 year-1), 7.7 % of the area was found to be under moderate erosion rate (5-10 t ha-1), 13.8 % of the area is under high erosion rate (10-20 t ha-1), while around 17.5 % of the area was under very high erosion rate (20-40 t ha-1 year-1). Severe erosion rate (40-80 t ha-1 year-1) was observed at 14.2 % of the study area, whereas very severe erosion rate (>80 t ha-1 year-1) described about 7.8 % of the watershed. The results of this work are in agreement with the soil erosion map of Serbia, the sediment yield measurements in the basin and with other, more detailed, studies in the watershed. Therefore, the presented methodology could be applied as a framework for the evaluation of erosion factors on soil resources in South-eastern Serbia when limited data are available. The outputs of these studies can be used for the identification of vulnerable areas on a cell basis and for planning of conservation practices. © 2012 Springer-Verlag.

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