各种土壤粘结力.ppt

CHAPTER 12 SOIL TILLAGE AND MANAGEMENT  Sectionl Concept of soil tillage and basic manipulation Concept of soil tillage Tillage- The mechanical manipulation of the soil profile for any purpose tillage-oldest procedure of agriculture to manipulate the soil to improve crop production Farmers of West Africa preparing their land for planting  Tillage -Modern  Tillage uses more che rgy than any other cropping procedure Tillage requires time since lifting the soil and moving it can not be done rapidly  Tillage-Obiectives (1)Preparation of seedbed (2)Control of weeds (3)Fluff soil-reduce bulk density of root zone (4)Soil and Water conservation 犁侧板后 犁側板 图121烨犁主犁示意图 图123铁链耙架尖齿把  三、 Basic manipulation of tillage 1、 Plowing 框架总成 提升臂 2、 Preparation of soil 平行提升连杆 3、 Intertillage 通用机架 4 Other tillage manipulation 铲柱或 两个单独机组 图125旋耕机 图124中耕机  Section 2 Mechanics natures of soil A Soil coherence The natures of soil coherence Van der Waals force, hyo drogen bond. coulombian force and water membrane surface tension.E Affect the factors of soil 10 coherence d its affect the factors 图126土壤水分含量与粘结力的关系 曲线C的粘结力单位为:克英寸 2 Soil moisture content (1英寸=2.54cm)  表12-1各种土壤的粘结力 及对铁片的粘着力( Schubler) 干土的相对粘结力湿土对铁片的粘着 土壤 (以灰色纯粘土作 力 为100) (磅/英尺2) 1.硅质纯砂土 0.0 3.8 2腐殖质 8.7 8.8 3.菜园土 7.6 6.4 4砂粘土 57.3 7.9 5壤粘土 688 10.6 6灰色纯粘土 100.0 17.2  Soil adhesivity Soil plastic Plastic -A soil capable of being molded or deformed continuously and permanently, by relatively moderate pressure, into various shapes. 原来的杂乱排列 揉捏后的平行排列 图127片状粘粒塑性的显现  The liquid limit is the gravimetric moisture content at which the soil changes from being plastic and starts to behave as a viscous liquid The plastic limit is the gravimetric moisture content at which a soil changes from being friable into being plastic The plasticity index is defined as the difference between the liquid and plastic limits Atterberg limits- The collective de