9423

8705

كارشناسي ارشد

كشاورزي - خاك شناسي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1393

دوازده،103ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

حسين خادمي، محمدرضا مصدقي

شمس اله ايوبي

10/10/93

مهران شيرواني، مهدي قيصري

مهندسي كشاورزي

ID8705

104 Mapping the Structural Stability of Surface Soils and its Relationship with Selected Physico chemical Properties Climate and Parent Materials in Isfahan Province Azam Yazdani AYH YAZDANY@yahoo com Date of Submission August 20 2014 Department of Soil Science College of Agriculture Isfahan University of Technology Isfahan 84156 83111 IranDegree MSC Language FarsiSupervisors Hossein Khademi hkhademi@cc iut ac ir Mohammad Reza Mosaddeghi mosaddeghi@cc iut ac irAbstractSoil structure is a key factor in soil functioning its ability to support plant and animal life and tomoderate environmental quality Soil structure influences soil water solute movement soil erosion crusting nutrient recycling ground water pollution and CO2 emission Aggregate stability is used as anindicator of soil structure Aggregation results from the rearrangement flocculation and cementation ofprimary soil particles The objectives of this study were to examine the spatial variability of topsoilaggregate stability and the affecting factors in Isfahan Province Based on the geology map 252 soilsamples were collected from 0 20 cm depth on a 20 20 km network Stability of large aggregates wasmeasured using the wet sieving method and mean weight diameter MWD geometric mean diameter GMD and percent of water stable aggregates WSA were calculated Stability of small aggregates wasassessed using readily dispersible clay RDC Some soil physical and chemical properties includingtexture organic matter carbonates gypsum pH EC SAR and CEC were also determined The impactsof different properties on aggregate stability were evaluated using correlation stepwise regression andspatial variability analyses Semi variogram and kriging techniques were used to analyze the spatialvariability of the soil structure indices Results showed that short time wet sieving i e 2 min wassuitable for evaluation of aggregate stability of the surface soils in Isfahan Province The MWD GMDand WSA were positively and significantly interrelated while they had negative and significant butweaker correlations with RDC The highest correlations belonged to GMD indicating that aggregate sizedistribution was predominantly log normal in the studied soils The correlation analysis showed thatorganic matter had least influence on aggregate formation and stability due to low organic matter contentin the studied soils However clay and gypsum contents have significant influence on aggregate stability whereas EC SAR and silt content are among the factors negatively affecting aggregates Whilesedimentary parent materials mainly produce stable aggregates due to greater clay and calciumenrichment coarse textured metamorphic parent materials result in weaker aggregates Kriging maps ofthe soil structure indices have good reliability although with a low accuracy Spatial variability analysesindicated that structure of the surface soil was weak and severely degraded in the eastern parts of theProvince In the west and southwest regions soil aggregate stability is moderately well Highestcorrelation coefficients were obtained for RDC suggesting that readily dispersible clay can suitablyevaluate soil structural stability in Isfahan Province Overall the results showed weak structural stabilityof the studied soils Therefore it is suggested to preserve and or increase the soil surface cover plantcover and gravel pavement against degrading factors in Isfahan Province

حسين خادمي، محمدرضا مصدقي

شمس اله ايوبي

مهران شيرواني، مهدي قيصري