第三章 土壤水分PDF.pdf

Chapter 3 土壤水分 Soil Water Soil Moisture （ ， ） Introduction Soil water is one of the soil components Soil mineral matter Soil water(solution) 土壤矿物质 (38%,v/v) 土壤水(15-35%,v/v) (95%,w/w) Soil Atmosphere Soil organic matter 土壤空气(15-35%,v/v) 土壤有机质 (12%,v/v) (5%,w/w) Soil water is one of the four soil fertilities water nutrient Atmosphere heat Soil water is the most active factor in soil Uptake by crops Solvent of mineral nutrition Decomposition and synthesis of soil organic matter Affect physical, chemical and biological properties of soil Importance of Water in Soil a) Biological Functions Critical factor in supporting plant growth Critical for living organisms within soil and OM decay b) Pedogenic Functions Chemical weathering of minerals (clays formation) Translocation of materials within soil c) Mechanical mixing of soils Desiccation cracks due to shrink-swell Cryoturbation (frost churning) d) Physical properties Moderates soil temperature General hydrologic exchange (evapotranspiration) Infiltration into groundwater §3-1土壤水分类型与性质 § 3-1 The form and properties of soil moisture 固态水 ：冰 ，冬季寒冷的中高纬度地区 （solid water） 气态水 :水汽 ，易凝结为液态水 化合水 ：H Al Si O · 8H O 2 2 2 2 （vaporous water ）