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Soil is in close cooperation with the broader biosphere. The maintenance of fertile soil is "one of the most vital ecological services the living world performs", and the "mineral and organic contents of soil must be replenished constantly as plants consume soil elements and pass them up the food chain". [3]
Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. [3] It also refers to the soil's ability to supply plant/crop nutrients in the right quantities and qualities over a sustained period of time.
The growth of trees is another source of disturbance, creating a micro-scale heterogeneity which is still visible in soil horizons once trees have died. [190] By passing from a horizon to another, from the top to the bottom of the soil profile, one goes back in time, with past events registered in soil horizons like in sediment layers.
Nutrients in the soil are taken up by the plant through its roots, and in particular its root hairs.To be taken up by a plant, a nutrient element must be located near the root surface; however, the supply of nutrients in contact with the root is rapidly depleted within a distance of ca. 2 mm. [14] There are three basic mechanisms whereby nutrient ions dissolved in the soil solution are brought ...
The table below displays the deal bulk densities that both allow and restrict root growth for the three main texture classifications. The porosity of a soil is an important factor that determines the amount of water a soil can hold, how much air it can hold, and subsequently how well plant roots can grow within the soil. [14] Soil porosity is ...
Animals serve to decompose plant materials and mix soil through bioturbation. [70] Soil is the most speciose (species-rich) ecosystem on Earth, but the vast majority of organisms in soil are microbes, a great many of which have not been described. [71] [72] There may be a population limit of around one billion cells per gram of soil, but ...
The perpetually warm, wet climate makes these environments more productive than any other terrestrial environment on Earth and promotes explosive plant growth. [2] A tree here may grow over 23 m (75 ft) in height in just 5 years. From above, the forest appears as an unending sea of green, broken only by occasional, taller "emergent" trees.
When the organic component of a soil is substantial, the soil is called organic soil rather than mineral soil. A soil is called organic if: Mineral fraction is 0% clay and organic matter is 20% or more; Mineral fraction is 0% to 50% clay and organic matter is between 20% and 30%; Mineral fraction is 50% or more clay and organic matter 30% or ...