of the Earth and the biosphere of terrestrial plants and animals. It is an emergent result of living and nonliving processes creating a substrate allowing the effective use of solar energy to create and animate living matter. Life is the animation of minerals, and as terrestrial animals, nearly all the minerals in our bodies have historically come from soil. Soil is much more than dirt. It is a living community densely packed with tiny animals, microorganisms, bacteria, fungi, insects and much more - all in constant interaction. It’s composed of air, water, living organi sms, various stages of decaying organic carbon, and finely-ground rock particles with an effectively huge surface area for the leaching of trace elements. For these reasons, soil is also inherently fragile, susceptible to losing its biodiversity and effectiveness, having its minerals depleted, becoming insufficiently aerated or hydrated, or washing away entirely in the rain and wind if not held fast by networks of roots. Soil organic matter is the original fertilizer for crops. As organic matter is decomposed by microorganisms, nutrients are released into solution that enable crops to grow. Agricultural soils are about 45% minerals, 5% organic matter, and 50% air and water. 102 The organic matter in soil increases when the deposition of plant matter exceeds decomposition. Perennial plant communities, especially biodiverse grasslands and their associated herds of ruminants, are largely responsible for building up organic matter in the world’s best farm soils. When crops are harvested and trucked away, minerals are removed from the soil and local ecosystem. The elements carbon, nitrogen, oxygen, and hydrogen move between air and soil and can rapidly and reliably be locally regenerated, whereas all other elements, such as phosphorus, potassium, sulfur, magnesium, calcium, and boron are slowly (and unreliably) replenished through source rocks, flood and volcanic deposition, or human intervention. Most food crops are annual plants that require frequent soil disturbance to be established and don’t produce an excess of organic matter to rebuild soil stores. Tillage accelerates organic matter decomposition. Synthetic fertilizers, by importing nutrients no longer stored in healthy soils, hide the decline of soil organic matter and minerals that has been documented in farm soils around the world. Synthetic nitrogen accelerates the decomposition of organic matter, even with no-till farming. The formerly rich farmland in the US Midwest has completely lost over 100 million acres of its topsoil. 103
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