In ecology, the cycle in which organic and inorganic nutrients are transformed and move through the soil, living organisms, the atmosphere and water. In agriculture, it refers to the return to the soil of nutrients absorbed from the soil by plants. Nutrient recycling can occur through leaf fall, root exudation (secretion), recycling of residues, incorporation of green manures, and so on.



▶ Soil organic matter is the product of the chemical decomposition of animal and microorganism excretions, plant residues or the degradation of any of them after their death.

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In general, organic matter is classified into humic and non-humic compounds. In the latter, the chemical composition and even the physical structure of the original animal or plant tissues still persist.
Soil organisms decompose this type of organic substances leaving only residues that are difficult to attack, such as some oils, fats, waxes and lignins from plants.
Namely in nutrient recycling there is a process called leaching, which is a process in which a liquid solvent is passed through a pulverized solid so that dissolution of one or more of the soluble components of the solid occurs.

There is another process called aerobic that occurs in the presence of oxygen. For a compost to work successfully, sufficient oxygen must be provided to maintain the aerobic process, even in the presence of living organisms that can be observed with the naked eye (spiders, earthworms, rodents, ants, beetles).
NOTE: Reference material.