اثر بقاياي گياهي بر خواص هيدروليكي و وضعيت رطوبتي خاك هاي شاليزاري گيلان

چكيده انگليسي :

Effects of Crop Residue on Hydraulic Characteristics and Moisture Conditions of Paddy Soils in Guilan Maryam M oazzeni maryam moazany@yahoo com March 8 2009 Department of Water Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiProf Seyed Farhad Mousavi mousavi@cc iut ac irProf Behrouz Mostafazadeh Fard behrouz@cc iut ac irAbstractThe role of water and irrigation is vital in cultivation of rice in Iran The dominant method of irrigation in paddyfields in Iran is continuous flooding which changes to periodical method in time of water deficiency Cracks are themain problem in periodical irrigation The amount of water required in periodical irrigation method is several timesgreater that flooding irrigation Crop residues in paddy fields are able to prevent establishment of cracks and theirintensity I the present research effect of different levels of crop residue on soil hydraulic characteristics and controlof amount and intensity of cracks in some paddy Soils of Guilan Province is studied The experiment was performedas split split plots based on complete randomized blocks design using four soil textures and three replications Soiltexture as the main factor in 4 levels rice stem residues as sub factor in 7 levels 0 2 3 4 5 6 and 7 and soilmoisture stages in dry and wet conditions as sub sub factor in 5 levels primary stage T1 initial crack stage T2 crack area 13 17 cm2 final crack stage T3 crack area 55 59 cm2 final cracks get back to the initial stage W1 and crack disappearance W2 were considered Effect of addition different levels of rice residues on moisturecontent bulk density resistance to penetration of a penetrometer i e compaction height of soil subsidence andswelling volume of soil number of days for crack formation volume of water used in wet stage and saturatedhydraulic conductivity of soils were studied The results showed that soil texture levels of crop residues cracktreatment and their interaction have significant effect p 0 01 on moisture content bulk density penetration heightof soil volume of soil and days to crack formation Increasing the level of rice residues caused moisture content height and volume of soils to increase with respect to control and decreased the bulk density Addition of riceresidues increased generally the penetration of soil and delayed the crack formation In drying stage of soil samples from T1 to T3 moisture content and height and volume of soil was decreased In wetting stage from W1 to W2 moisture content height and volume of soil was increased In drying stage bulk density penetration days to crackformation from T1 to T3 increased In wetting stage bulk density and penetration from W1 to W2 was decreased but days to crack formation was increased In silty clay soil addition of 2 and 3 crop residue caused an expeditionin crack formation and addition of 4 7 crop residue caused a delay in crack formation as compared to controltreatment In silty clay loam texture addition of 3 4 and 5 crop residue caused an expedition in crack formation and addition of 6 and 7 crop residue caused a delay in crack formation as compared to control treatment Additionof rice residue in light textured soils of clay loam and sandy loam caused a delay in crack formation Soil texture levels of rice residue crack treatment and interaction of soil texture and levels of crop residue and interaction of soiltexture and crack treatment caused significant difference on volume of water used in wetting stage Volume of waterused in wetting stage was increased from light to heavy textured soils Addition of crop residues increased saturatedhydraulic conductivity of all the studied soils Key Words Paddy field Periodical irrigation Crop residue Soil moisture Bulk density Compaction Days to crack formation Saturated hydraulic conductivity

موذني، مريم

اثر بقاياي گياهي بر خواص هيدروليكي و وضعيت رطوبتي خاك هاي شاليزاري گيلان

آبياري نوبتي , وزن مخصوص ظاهري , تراكم , تعداد روز تا تشكيل ترك , هدايت هيدروليكي اشباع