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Soil health is a state of a soil meeting its range of ecosystem functions as appropriate to its environment. Soil Health Testing is an assessment of this status (NRCS 2013). == Aspects== The term soil health is used to describe the state of a soil in: *Sustaining plant and animal productivity and diversity; *Maintaining or enhance water and air quality; *Supporting human health and habitation. 〔http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/co/home/?cid=nrcs144p2_063020〕 Soil Health has partly if not largely replaced the expression "Soil Quality" that was extant in the 1990s. The primary difference between the two expressions is that soil quality was focused on individual traits within a functional group, as in "quality of soil for maize production" or "quality of soil for roadbed preparation" and so on. The addition of the word "health" shifted the perception to be integrative, holistic and systematic. The two expressions still overlap considerably. The underlying principle in the use of the term “soil health” is that soil is not just an inert, lifeless growing medium, which modern farming tends to represent, rather it is a living, dynamic and ever-so-subtly changing whole environment. It turns out that soils highly fertile from the point of view of crop productivity are also lively from a biological point of view. It is now commonly recognized that soil microbial biomass is large: in temperate grassland soil the bacterial and fungal biomass have been documented to be 1–2 tons/hectare and 2–5 t ha, respectively.〔Microbial diversity and soil functions. European Journal of Soil Science, December 2003, 54, 655–670〕 Some microbiologists now believe that 80% of soil nutrient functions are essentially controlled by microbes.〔Dr. Kris Nichols Role of Soil Biology in Improving Soil Quality See External Link Below〕 If this is consistently true, than the prevailing Liebig nutrient theory model, which excludes biology, is perhaps dangerously incorrect for managing soil fertility sustainably for the future. We can use the human health analogy and categorise a healthy soil as one: *In a state of composite well-being in terms of biological, chemical and physical properties; *Not diseased or infirmed (i.e. not degraded, nor degrading), nor causing negative off-site impacts; *With each of its qualities cooperatively functioning such that the soil reaches its full potential and resists degradation; *Providing a full range of functions (especially nutrient, carbon and water cycling) and in such a way that it maintains this capacity into the future. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「soil health」の詳細全文を読む スポンサード リンク
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