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Plants obtain inorganic elements from the soil, which serves as a natural medium for land plants. Soil is the outer, loose layer that covers the surface of Earth. Soil quality, a major determinant, along with climate, of plant distribution and growth, depends not only on the chemical composition of the soil, but also the topography (regional surface features) and the presence of living.
Soil texture is a qualitative classification tool used in both the field and laboratory to determine classes for agricultural soils based on their physical texture. The classes are distinguished in the field by the "textural feel" which can be further clarified by separating the relative proportions of sand, silt and clay using grading sieves.
A soil horizon is a layer generally parallel to the soil crust, whose physical characteristics differ from the layers above and beneath. Each soil type usually has three or four horizons. Horizons are defined in most cases by obvious physical features, chiefly color and texture. These may be described both in absolute terms and in terms relative to the surrounding material.
Rate of Soil Formation
Importance of soil
The properties of soil that affect plant growth include texture, aeration , porosity, water holding capacity and aggregate size.A vital function of soil is storing and supplying minerals and nutrients essential for plant life. This is referred to as soil fertility. The proportions of clay and organic matter found in soil influence its fertility.As a regulator and collector of water, soil absorbs and stores moisture for plants and organisms to use. It also shelters plants against extreme temperatures and protects roots from direct sunlight. Moreover, living organisms of various sizes thrive in soil. There are microorganisms and insects in soil that improve it, allowing plants to grow better. These tiny microorganisms, such as fungi and bacteria, decompose the soil and transform old, dead materials into raw materials that plants need for growth.The quality of soil is important for the health of plants and the humans and animals that consume plants.