Soil
![Soil measuring and surveying device](https://upload.wikimedia.org/wikipedia/commons/a/a8/EAgronom_4okt2023_L-1120.jpg)
Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem.
Most soils have a dry bulk density (density of soil taking into account voids when dry) between 1.1 and 1.6 g/cm3, though the soil particle density is much higher, in the range of 2.6 to 2.7 g/cm3. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, although fossilized soils are preserved from as far back as the Archean.
Collectively the Earth's body of soil is called the pedosphere. The pedosphere interfaces with the lithosphere, the hydrosphere, the atmosphere, and the biosphere. Soil has four important functions:
* as a medium for plant growth * as a means of water storage, supply, and purification * as a modifier of Earth's atmosphere * as a habitat for organisms
All of these functions, in their turn, modify the soil and its properties.
Soil science has two basic branches of study: edaphology and pedology. ''Edaphology'' studies the influence of soils on living things. ''Pedology'' focuses on the formation, description (morphology), and classification of soils in their natural environment. In engineering terms, soil is included in the broader concept of regolith, which also includes other loose material that lies above the bedrock, as can be found on the Moon and other celestial objects. Provided by Wikipedia
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321by Asia Soil Conservation Network for the Humid Tropics, Jakarta (Indonesia). Coordination Unit eng
Published 1990Texto bibliotecaFAO IT -
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323by Asia Soil Conservation Network for the Humid Tropics, Jakarta (Indonesia). Coordination Unit eng
Published 1990Texto bibliotecaFAO IT -
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326by Dey, J., Landbouwuniversiteit, Wageningen (Netherlands). Dept. of Irrigation and Soil and Water Conservation oth
Published 1990Texto bibliotecaFAO IT -
327by Department of Soil Conservation and Watershed Management, Kathmandu (Nepal). Technology Development Section eng
Published 1991Texto bibliotecaFAO IT -
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331by Levenson, B., Ministry of Forests, Kathmandu (Nepal). Dept. of Soil and Water Conservation eng
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332by Cornell Univ., Ithaca, NY (USA). Soil Resource Inventory Study Group eng
Published 1987Texto bibliotecaFAO IT -
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