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1 BASIC CONCEPTS OF SOIL Definition of soil Soil is a natural and dynamic body occurring on the surface of the earth in places made or modified by man using earthy materials containing living matter supporting or capable of supporting plant growth out of door. A soil or an individual soil has three dimensions (Length, Width, and Height) just like a body of water. A soil occupies a small three –dimensional part of the land surface. The water or a soil can be sampled and analyzed in the laboratory. Limits of soil a)Upper Limit- generally considered as air or water. The atmosphere or shallow waters.b)Lateral Limit- deep water or barren areas of rock, ocean ice caps, salt, or shifting desert sand dunes. Sediments at depths greater than where emergent plants grow is not considered as soil. c)Lower Limit- difficult to define, but generally thought of as the common rooting depth (shallow in deserts, deep in humid tropics) of the native perennialplant.Lowest limit of biological activities i.e. the rooting zone, weathering materials. Concept about soil During the early development of soil science, the concept of soil differs among investigators with different disciplines or background. 1.Pedologist - study of soil as a natural entity - origin, classification and description. 2.Edaphologist - study of soil from the standpoint of plant growth. Medium of for supporting plant growth. A person's concept of soil depends on his/her viewpoint and experience. 3.Engineer - loose or broken rock material at the earth's surface. This material can be used for building purposes. 4.Geologist - highly weathered rock. Part of the material that makes up outer mantle of the earth. 5.Horticulturalist - material that needs sterilizing and modification before using for plant growth in greenhouses. 6.Turf Specialist - material that supports foot and cart traffic, grows grass, and will provide a good fairway or putting surface. Will modify it to suit their needs.