5751

5366

كارشناسي ارشد

مكانيك ماشين هاي كشاورزي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1389

هجده،131ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

عباس همت

محمدرضا مصدقي

27/1/90

امين ا...معصومي، منوچهر حيدرپور

مهندسي كشاورزي

ID5366

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Topsoil and Subsoil Bearing Capacity Assessment with Plate Sinkage Test under Different Ratoon Crops in a Sugarcane Field Aliyeh Veisi Tabar a veisitabar@yahoo com Aug 3 2010 Department of Agricultural Machinery Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiProfessor Abbas Hemmat ahemmat@cc iut ac irAbstractSoil compaction affects soil physical properties through increasing soil bulk density changing the pore sizedistribution as well as the pores tortuosity and connectivity decreasing water infiltration into the soil andair permeability and soil aeration increasing soil mechanical resistance and modifying the soil structure Asa result of soil compaction longitudinal root growth is intensively reduced or even stopped whenencountering compacted layers and hard pans Hence it reduces water and nutrition uptake by the plantsand consequently the crop yields are reduced In addition to intrinsic properties e g texture and physicalproperties e g water content and bulk density of soil machine related factors such as axle load tire sizeand pressure effectively influences the soil compaction In sugarcane farms soil compaction phenomenonis considerable and remarkable Soil compaction in sugarcane farms occurs mainly due to mechanizedoperations during intensive crop production by using very heavy machinery The highest stresses areinduced in the soil by large harvesters and haulout equipments which are heavy and have low soil tirecontact area and high inflation pressure Among the parameters used for evaluation of soil compactibility pre compaction stress pc and deformability coefficient CD are very useful They are used as the stressthreshold for soil compaction and the soil sensitivity to irreversible compaction when the applied stressesdue to the field traffic exceed the pc respectively The objectives of this research were a to determine pc and CD of soils with different textures under different planting conditions fallow plant crop firstratoon crop and second ratoon crop and b to derive pedo transfer functions PTFs for estimating soil pcand CD using easily available soil properties In order to achieve the objectives three different platesinkage tests PST including 20 mm sinkage loading constant cycling loading and staircase loading wereconcurrently conducted in each soil texture while soil water content bulk density and cone index weremeasured simultaneously Results showed that the PST can be used to estimate the load bearing capacity ofthe soil The soil compression curves vertical stress vs sinkage showed two major soil groups a soilswith specific load bearing capacity and b soils sensitive to compaction or with very low load bearingcapacity In fields which were under planting the effect of soil texture on pc was significant but the effectof measuring depth topsoil or subsoil and their interaction were not significant Therefore if the soil

عباس همت

محمدرضا مصدقي

امين ا...معصومي، منوچهر حيدرپور