期刊级别该如何划分 ？.ppt

* * * * * * * * * * * * * * * * * * * * * * Soil Types and Textures 期刊杂志 Definitions Soil Texture The way a soil feels A name given a textural group based on the relative proportions of each size of soil particle Definitions Aggregate Mass or cluster of soil particles such as a clod, crumb or granule Soil Structure The combination or arrangement of soil particles into aggregates Objectives Define aggregate, soil structure, and soil texture Identify and describe the three basic soil particles Identify the major textural classes SOIL - Fundamental Concepts Prepared by Earl D. Lockridge National Soil Survey Center Lincoln, NE /education/resources/k_12/tools.html SOIL Geologic definition: Loose surface of the earth as distinguished from solid bedrock (support of plant life not required). Traditional definition: Material which nourishes and supports growing plants (includes rocks, water, snow, air). Air 25% Mineral Matter 45% Water 25% Organic Matter 5% SOIL Component definition: Mixture of mineral matter, organic matter, water, and air. SOIL Soil Taxonomy definition: Collection of natural bodies of the earth’s surface, in places modified or even made by man or earthy materials, containing living matter and supporting or capable of supporting plants out of doors. (Its upper limit is air or shallow water and its lower limit is the depth to which soil weathering has been effective.) Soil Taxonomy At the highest level, soils can be recognized in one of 12 categories known as orders. For more information: /soilorders SOIL As a portion of the landscape: Collection of natural bodies occupying portions of the earth’s surface that support plants and that have properties due to the integrated effect of climate and living matter, acting upon parent material, as conditioned by relief, over periods of time. Soil Forming Processes Translocations Transformations Additions Losses Physical Properties of Soil Soil texture Soil structure Soil color Bulk density Three Fractio