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Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    1-18
Measures: 
  • Citations: 

    0
  • Views: 

    832
  • Downloads: 

    0
Abstract: 

The bioavailability and mobility of metals in soils are dependent upon distribution of these metals between solution and solid phases and among solid phase components. A sequential extraction procedure was used to investigate the distribution of Zn among soil fractions for 15 soils of Golestan province that varied in physical and chemical properties. The results revealed that about 0.51, 0.41, 1, 0.44, 8.24, 22.15 and 67.23% of the total soil Zn was present in water-soluble and exchangeable (Ex), carbonates-bound (Car), organically bound (OM), Mn-oxidebound (Mnox), amorphous Fe-oxide-bound (AFeox), crystalline Fe-oxide-bound (CFeox) and residual (Res) forms, respectively. Organic carbon was significantly positively correlated with Zn associated with Mnox, CFeox and total Zn. Cation exchange capacity was significantly positively correlated with Zn in Mnox and AFeox fractions, but did not show correlations with other fractions including Ex- Zn. Organically bound Zn did not show significant correlations with any soil properties. Correlation coefficient between calcium carbonate equivalent and carbonate-bound Zn was not significant. No correlations were observed between soil pH and Zn fractions except with organically bound Zn. Total Zn shows significant correlations with all Zn fractions except Ex-Zn, OM and Mnox fractions. DTPA erxtractable Zn was significantly positively correlated with Zn associated with AFeox and total Zn.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    21-36
Measures: 
  • Citations: 

    0
  • Views: 

    940
  • Downloads: 

    0
Abstract: 

The presence of excessive amounts of exchangeable sodium on sodic soils adversely affects the physico-chemical properties of these soils. Organic matter and minerals amendments were used to improve the properties of sodic soils. To study the effects of different levels (0, 2.5, and 5%) of alfalfa residue without or with gypsum and aluminum sulfate on physical properties of a sodic soil a greenhouse experiment with 9 treatments was conducted in Zanjan University using a completely randomized design and three replications. After addition of different treatments to soil samples, they were incubated for four months at moisture content of field capacity. Physical properties of the soil samples including stability of soil aggregates (measured as mean weight diameter), hydraulic conductivity and plant available water were measured after incubation of two and four months intervals. Aggregates with diameters of 250-500 mm and 500-1000 mm increased significantly with respect to control after 2 and 4 months of incubation respectively. The highest plant available water was obtained from treatments with 5% alfalfa residue+ gypsum or 5% alfalfa residue+ aluminum sulfate and these treatments increased this attribute by 26.5% and 23.5% respectively compared to control. The most effective treatment in increasing hydraulic conductivity was aluminum+ 5% alfalfa residue stood in second place. The results of this research indicate the importance of organic matter and calcium bearing compounds for improving physical properties of sodic soils.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    39-58
Measures: 
  • Citations: 

    1
  • Views: 

    1012
  • Downloads: 

    0
Abstract: 

Soil sensitivity to structure destruction trends is an important criterion to determine the agronomic ability of a soil. This sensitivity is characterized by the concept of physical structure stability which in spite of structure destruction factors effect, shows the ability of structural component stability. The objective of this research were to investigate the factors affecting soil aggregate stability in an extensive area of Shastkalateh forest in soils originated from three different geological parent materials and also to determine the aggregate stability in order to study erosion Soil. Using the Geology and Topographic maps therefore 20 points were selected as mixture and completely random design and sampling was carried out from 0-20 cm depth. Mean weight diameter was determined by wet sieving method. Physical properties such as soil texture and chemical properties including organic matter, calcium carbonates and Iron oxides were measured and linear and multiple regressions with stepwise method was performed to analyse the results. The results showed that Zhorasic parent material has the highest aggregate stability. Carbonate calcium Content (R2=0.67), iron (R2=0.78) and soil CEC of are the most effective factors on soil structure stability in Zhorasic parent material. Carbonate calcium content (R2=0.78), iron (R2=0.72) in Loess structure aggregate and organic matter content and iron (R2=0.5) in alluvial pareat material play the most important roles in stability.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    61-78
Measures: 
  • Citations: 

    0
  • Views: 

    1898
  • Downloads: 

    0
Abstract: 

Particle size distribution (PSD) and aggregate stability are known as the most important soil physical properties which have important influence on soil behavior. This study investigates the effect of soil physical and chemical properties on aggregate stability in some cultivation systems. The PSD in two statuses of dry (DPSD) and wet (WPSD) was studied in 6 cultivation systems consist of wheat, barley, maize, alfalfa, fallow and tilled land. The results showed that the cultivation systems had significant effects on water stable aggregates larger than 0.25 mm (WSA>0.25mm). Among different cultivation systems, alfalfa and wheat were found to be the best systems in establishing macro aggregates for the DPSD and WPSD, Respectively; however these aggregates for alfalfa were lower stable. The highest amounts of organic carbon were obtained in the wheat and barely cultivation systems (1.09% and 1.04%, respectively), while the other systems, showed no significant differences. All of the physical and some chemical properties (i.e. EC, pH, ESP, organic carbon, exchangeable sodium, and soluble cations) were influenced significantly by the cultivation systems, while this effect was not significant (p>0.05) for other chemical properties such as SAR, CEC, calcium carbonate, exchangeable calcium, magnesium and potassium. In addition, the primary PSD had significant influence on secondary PSD. There was a negative significant relationship between sand fraction and stable aggregates (wet and dry), while this relation was positive for silt. Clay content had no significant influence on macro aggregates. The results also indicated that in comparison to physical properties, chemical properties had less effect on WSA>0.25. In this regard, organic carbon was found as the most prominent factor which can control aggregate stability. The findings of this study reveal that larger aggregates are not always stable particles and based on the PSD, the concept of stability can not be described exactly.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    81-95
Measures: 
  • Citations: 

    3
  • Views: 

    2430
  • Downloads: 

    0
Abstract: 

Land use change of natural ecosystems in to managed ecosystems has had negative effects on soil properties and known as a destructive factor of soil physical and chemical properties. Because of extensive land use changes in Iran and especially in the Golestan province, the effect of land use changes on soil properties, in the Kechik catchment was studied. In this study, some physical and chemical properties of soil in different land uses (forest: 612 ha, rangeland 1130 ha, and agriculture1806 ha) were determined and the difference between their means were studied. The results indicated that because of land use changes, soil texture has changed from sandy-clay-loam to sandy-loam and soil classes changed from clay with high plasticity class to clay with low plasticity class. The soil mean weight diameter has also decreased and agricultural soil has lower porosity and higher bulk density than other soils. The level of soil organic matter, organic nitrogen, and cation exchange capacity were meaningfully lower in agricultural soil as compared with other soils.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    97-117
Measures: 
  • Citations: 

    0
  • Views: 

    1128
  • Downloads: 

    0
Abstract: 

it is necessary to use the phosphate rock (PR) because of the globally increasing chemical phosphate fertilizers price and huge resources of domestic PRs. There is a negligible knowledge on mycorrhizal fungi and native PRs sources influence on phosphorous uptake. Therefore a pot experiment was carried out to investigate the effect of mycorrizal fungi on enhancement of phosphate uptake from native PRs sources in soybean in 2010. Experiment was factorial with four replicates. Factors were included none-inoculation (M0) and inoculation (M1) to mycorrhizae plus five sources of phosphate (B1: control without phosphate amendment, B2: standard phosphate fertilizer from triple superphosphate, B3: Yazd rock phosphate, B4: Yasouj rock phosphate and B5: Gafsa rock phosphate from Tunisia). Results showed Gafsa PR produced the highest phosphorous concentration of root and shoot, shoot nitrogen and dry matter among the applied PRs. In the Gafsa rock phosphate inoculated by mycorrhiza phosphorous uptake was higher than other PRs. Gafsa inoculated to mycorrhiza, had the maximum relative agronomic effectiveness based on phosphorus uptake (60.54%) and relative agronomic effectiveness based on shoot dry matter (39.65%). Mycorrizal colonization index in Gafsa was higher than other PRs. Generally, mycorrhiza markedly increased phosphorus uptake from Gafsa PR more than the domestic PRs.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    2
  • Pages: 

    119-135
Measures: 
  • Citations: 

    0
  • Views: 

    767
  • Downloads: 

    0
Abstract: 

Heavy metals are categorized as one of the most important contaminants that disturb soil environment and thus are harmful to terrestrial organisms. There are many ecological indices representing such pollutions. Nematodes as indicator organisms may be a suitable index to assess environmental conditions. The objective of this study was to investigate the impact of different levels of selected heavy metals (Cd, Ni, and Pb) and cow manure on nematode population changes of indigenous soil nematodes. A completely randomized design with factorial arrangement was carried out including three levels of heavy metals 0 (H0); 100, 500, 1000 (H1); and 300, 700, 2000 (H2) mg kg-1 of Cd, Ni and Pb respectively and two levels of cow manure 0 (O0) and 1% (O1) with 3 replications. Soil moisture of all treatments was adjusted at 70% of field capacity. All treatments were incubated for 30 and 90 days. Soils were then washed and the total population, juvenile and mature numbers of nematodes was determined. All isolated nematodes were identified at the family level and ecological indices (enrichment, structure and maturity) were determined. The results showed that total population, juvenile, mature numbers of nematodes decreased significantly in all metal amended treatments. Furthermore, calculated ecological indices tended to decline by addition of heavy metals into soil samples.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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