Các lớp học kết cấu đất (ví dụ, mùn, đất sét, sét pha, cát pha sét) được ước tính về kích thước và phân phối của các hạt tiểu học bằng cách sàng và phân tích trầm tích. Ước tính lĩnh vực của kết cấu được xác nhận bởi các phân tích phòng thí nghiệm mẫu được lựa chọn. Phân tích kích thước hạt (PSA) là một phép đo kích thước hạt phân phối. Hệ thống thông tin đất Canada thuật ngữ xác định kích thước hạt phân phối số tiền của đất khác nhau tách biệt trong một mẫu. | VI. SOIL PHYSICAL ANALYSES Section Editors Denis A. Angers and . Larney 2006 by Taylor Francis Group LLC. 2006 by Taylor Francis Group LLC. Chapter 55 Particle Size Distribution D. Kroetsch and C. Wang Agriculture and Agri-Food Canada Ottawa Ontario Canada INTRODUCTION Soil textural classes . loam clay loam sandy loam are estimated in terms of size and distribution of primary particles by sieve and sedimentation analysis. Field estimates of texture are confirmed by laboratory analyses of selected samples. Particle size analysis PSA is a measurement of particle size distribution. The Canadian Soil Information System glossary defines particle size distribution as the amounts of the various soil separates in a soil sample usually expressed as weight percentages Gregorich et al. 2001 . According to Gee and Or 2002 two major features of PSA are the destruction or dispersion of soil aggregates into distinct units by chemical mechanical or ultrasonic means and the further separation of these particles into size classes by sieving and sedimentation. The proportions are calculated from the relative weights of the particles within defined size classes. The primary particle size classes used in this chapter are defined in the Canadian System of Soil Classification CSSC Soil Classification Working Group 1998 and are given in Table . The limits of soil particle size classes differ in various commonly used systems Figure . The CSSC the United States Department of Agriculture USDA and the International Society of Soil Science ISSS systems are used for soil survey data. The American Association of State Highway Officials AASHO and the Unified Systems American Society for Testing and Materials ASTM are used for engineering purposes. Two common methods of PSA are the pipette and hydrometer methods. In both the coarser fractions are measured by sieving and the finer from sedimentation rates based on Stokes law. Stokes law states that the amount that a particle .
