EURASIAN JOURNAL OF SOIL SCIENCE

194-201

Authors: Nalan Kars , Orhan Dengiz

Soil pollution, influenced by both the natural and anthropogenic factors, significantly reduces environmental quality. This research was carried out in some micro catchments located on Ordu province of Black Sea Region-Turkey in order to determine potential ecological risk index based on heavy metal elements (HMs) for organic farming. For this purpose, 166 soil samples (0-20 cm) were taken from the study area and some physical and chemical and HM concentrations (Cd, Cu, Cr, Ni, Pb and Zn) analysis were done. In this study, it was determined; i-) some physical and chemical properties of catchments’ soils, ii-) HM contents and the correlation relation between physico-chemical properties of soil and HM concentrations and iii-) potential ecological risk index (PERI). PERI was calculated using the data obtained to evaluate the environmental risks of HMs in the region. The results showed that Cu concentration in 3%, Cr in 0.6% and Ni in 4.8% of the soil samples exceeded the threshold levels whereas, the concentrations of other HMs were lower than the critical values. Statistically, it was also found significantly positive relationships between sand content and Cu of soils whereas, it was determined significantly negative relationships between EC and Cu. In addition, according to the obtained PERI results, while 54% of total soil samples were low while, 42% of them were moderate class. Only 4% of them were classified as significant ecological risk level. Moreover, according to mean potential ecological risk index of these HMs, it can be ordered as Cd>Pb>Cu>Ni> Zn>Cr.

208-221

Authors: Zeynep Demir

Effects of different cover crops (CCs), mechanically cultivation and herbicide treatments on soil organic matter (SOM) content and some physical properties of soils were investigated in a cherry orchard with clay soil in 2013 and 2014. The present study was conducted in a cherry orchard located at the Experiment Station of Black Sea Agricultural Research Institute in Samsun province in the Northern region of Turkey. As the CCs, Trifolium repens L. (TR), Festuca rubra subsp. Rubra (FRR), Festuca arundinacea (FA), T. repens (40%)+F. rubra rubra (30%)+F. arundinacea (30%) mixture (TFF), Vicia villosa (VV) and Trifolium meneghinianum (TM) were utilized. Experiment also included plots mechanically cultivation (MC), herbicide treatment (HC) and control (C) plot without CCs. Experiment was conducted in randomized complete blocks design with four replications. The CCs were mowed in the flowering period of the plants. After 90 d following seed harvest, soil samples were collected from two depths (0-20 and 20-40 cm) in each plot. The CCs treatments decreased bulk density, volumetric water content, relative saturation, penetration resistance and increased SOM, field capacity, permanent wilting point, available water capacity, total porosity, gravimetric water content, mean weight diameter, structural stability index. The differences in the SOM contents and physical soil properties of all treatments as compared to the control were not found to be significant for the 20-40 cm soil depth in both years of experiments. The CCs, especially TR and VV treatments as legume plants improved SOM and physical soil properties, but longer term studies are needed to evaluate the long-term effects.

231-241

Authors: Marina Burachevskaya , Tatiana Minkina , Tatiana Bauer , Saglara Mandzhieva , Coşkun Gülser , Rıdvan Kızılkaya , Svetlana Sushkova , Vishnu Rajput

This study is aimed at elucidating the fractionation of Cu and Zn in Haplic Chernozem and its alteration under the contamination to evaluate the extraction selectivity of different extractants and thus the efficiency of three sequential extraction schemes (Tessier and McLaren five-step and modified BCR three-step methods). General trends in the distribution of Cu and Zn speciations revealed with these three fractionation schemes suggest that they can be applied for the soils and the obtained results can be compared. Low mobility of potentially toxic metals (PTM) in the studied soil is suggested not only by their high content in residual fraction, but also by low contents of exchangeable and carbonate bound fractions (not more than 4-5 % Cu and 5-7 % Zn in the first two fractions). The highest contribution to the absorption and retention of Cu delivered from anthropogenic sources is made by organic matter and sesquioxides (up to 29 %); for Zn, by the nonsilicate Fe and Mn compounds (up to 25 %). However, the pattern of PTM extraction from soils varies during the application of different fractionation methods. The Tessier method is distinguished by a higher extractability relative to organic matter and sesquioxides. Therefore, this method is more informative for the contaminated soils. The McLaren method makes it possible to track the weakly bound species of compounds without the risk of involving other soil components. The BCR method is marked by simplicity of application and, therefore, recommended only for the noncalcic or low-calcic soils.

254-263

Authors: Nabil Charchar , Laid Bouchaala , Hani Bouyahmed , Abd El-Fatteh Gherib , Amel Lehout

The ecological importance of soil bacteria is not limited to their number or biomass, although these parameters contribute greatly. Indeed, their main asset lies in their great genetic and functional diversity.This study aims to determine heavy metal contamination levels of the soils of an abandoned mining area of Sidi Kamber (Skikda), impact of heavy metals on bacterial communities and the possible risks that can affect the ecological balance of this area. Soil samples from three zones (Zone A, B and C) were collected from the top layer (0–20 cm) of mining area. Chemical analysis (pH, organic matter, total organic C, total N, available P, and cation exchange capacity, metal content of (Pb, Cu, Cd, Zn and Ni) and bacterial analysis were carried in center for biotechnology research CRBt. Our results show that the mining area is characterized by an acid pH. Significant variations were observed for edaphic parameters (organic matter, total organic C, total N, available P and cation exchange capacity) between three sampling zones. The overall area was severely polluted with Cu, Cd, Pb, Ni and Zn with a total concentration far exceeding international standards. The bacterial load and diversity were relatively high with a significant variation between the three zones. The PCA analysis of the soil's characteristics indicates that the organic matter and the cation exchange capacity affect the distribution of the metallic trace elements in the soil and allowed us thus to a clear separation of the studied zones.

275-281

Authors: Reda Ragab Shahin , Hassan Ahmed Khater

Sekem commercial organic farm was chosen for the present work; it is located at Belbeis 20 Km northeast of Cairo city which represented sandy soils. Five plots in Sekem farm were chosen to represent different periods of organic farming application, i.e. 0, 12, 15, 18 and 23 yrs. Surface (0-20 cm) and subsurface (20-40 cm) soil samples were collected in both winter and summer season. The collected soil samples were subjected to the dry sieve analysis to determine and separate the dry aggregate size of ˂0.25, 0.25-0.50, 0.50-1.00 and 1.00-2.00 mm diameter. The distributions of total organic carbon were studied in the whole soil and its aggregate fractions. The data showed that total organic carbon significantly increased by increasing the period of organic farming in the surface samples especially in the longest period of organic farming. Total organic carbon was concentrated in the finest aggregate fraction (˂0.25 mm) for both summer and winter seasons and it was also increased by increasing the period of organic farming. The investigation of the humic and fulvic separates using infrared (IR) spectrophotometry, showed the dominance of carboxylic bands in fulvic especially in the subsurface soil samples which indicated its acidic function. Humic separates showed a relative increased in the intensity of aromatic bands as compared to fulvic separates with increasing the period of organic farming.