Section 2 Soil texture Soil particle and particle fraction(soil separates) Types of soil particle: Mineral soil particle and organic soil particle Single particle and compound particle .Primary particle and second particle ()Soil particle fraction (soil separates) Natural soils are comprised of soil particles of varying sizes. The soil particle-size groups, called soil particle fraction(soil separates), are sands(the coarsest), silts, and clays(the smallest)
(一) Types of soil particle： • Mineral soil particle and organic soil particle • Single particle and compound particle •Primary particle and second particle (二) Soil particle fraction (soil separates) Natural soils are comprised of soil particles of varying sizes. The soil particle-size groups, called soil particle fraction (soil separates), are sands (the coarsest), silts, and clays (the smallest). 一、Soil particle and particle fraction (soil separates) Section 2 Soil texture
Particle Diameter size Soil particle diameters range over 4 orders of magnitude Boulders Sand Silt clay
Particle Diameter Size • Soil particle diameters range over 4 orders of magnitude – Boulders – Sand – Silt – Clay
Kachinsky classification system of soil separates Physical sandy particle I mm to 0.01 mm Physical clay particle: <0.01mm
Physical sandy particle: 1 mm to 0.01 mm. Physical clay particle: < 0.01 mm Kachinsky classification system of soil separates
表43常见的土壤粒级制 ) 当量粒径 中国制 卡钦斯基制 美国农部制 际制 (mm) (1987) (1957) (1951) (1930) 石砾 石砾 石砾 石砾 2~1 极粗砂粒 1~0.5 粗砂粒 粗砂粒 粗砂粒 粗砂粒 0.5~0.25 中砂粒 砂 0. 25~0.2 0.2~0.1 细砂粒 物理性砂粒 细砂粒 细砂粒 0.1~0.05 极细砂粒 细砂粒 0.05~0.02 粗粉粒 粗粉粒 0.02~0.01 粉粒 0.01~0.005 中粉粒 中粉粒 粉粒 0.005~0.002 细粉粒 物 细粉粒 0.002~0.001 粗粘粒 理 性 0.001~0.0005 粘 粗粘粒 粘粒 0.0005~0.0001 细粘粒 粒粘细粘粒 粘粒 <0.0001 胶质粘粒
Soil particle Classification system of soil separates:(mm) Diameter International USDA Kachinsky Chinese B ouders >2 2 Sand 2-0.02 2-0.05 1-0.05 1-0.05 Silt0.02-0.002005-0.0020.05-0.0010.05-0.002 Clay 〈0.002〈0.002 〈0.001 〈0.002
Soil particle Classification system of soil separates ：(mm) Diameter International USDA Kachinsky Chinese Boulders >2 >2 > 1 >1 Sand 2-0.02 2-0.05 1-0.05 1-0.05 Silt 0.02-0.002 0.05-0.002 0.05-0.001 0.05-0.002 Clay 〈0.002 〈0.002 〈0.001 〈0.002