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Estimates of bioavailability can also be obtained from chemical solid-phase soil extractions. [7] Fugacity modelling of bioavailability is based on the solubility and partitioning of compounds into aqueous and non-aqueous phases. [8] This model describes the tendency for contaminants to be dissolved in the soil solution.
It is commonly a limiting factor in the production of crops (due to solubility limitation or absorption of plant nutrients to soil colloids) and in the removal of toxic substances from the food chain by microorganisms (due to sorption to or partitioning of otherwise degradable substances into inaccessible phases in the environment).
Mineralization increases the bioavailability of the nutrients that were in the decomposing organic compounds, most notably (because of their quantities) nitrogen, phosphorus, and sulfur. Whether the decomposition of an organic compound will result in mineralization or immobilization is dependent on its concentration proportionate to that of the ...
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 ...
Soil fertility is a complex process that involves the constant cycling of nutrients between organic and inorganic forms. As plant material and animal wastes are decomposed by micro-organisms, they release inorganic nutrients to the soil solution, a process referred to as mineralization. Those nutrients may then undergo further transformations ...
When available N exceeds the ecosystem's (i.e., vegetation, soil, and microbes, etc.) uptake capacity, N saturationoccurs and excess N is lost to surface waters, groundwater, and the atmosphere. [12] [17] [18] N saturation can result in nutrient imbalances (e.g., loss of calcium due to nitrate leaching) and possible forest decline. [13]
Soil erosion occurs naturally, but human activities can greatly increase its severity. [28] Soil that is healthy is fertile and productive. [29] But soil erosion leads to a loss of topsoil, organic matter, and nutrients; it breaks down soil structure and decreases water storage capacity, reducing fertility and water availability to plant roots.
Soil fauna affect soil formation and soil organic matter dynamically on many spatiotemporal scales. [5] Earthworms, ants and termites mix the soil as they burrow, significantly affecting soil formation. Earthworms ingest soil particles and organic residues, enhancing the availability of plant nutrients in the material that passes through and ...