The highly soluble nitrate ion may be leached from soils into fresh waters. High concentrations of nitrate are toxic, and therefore denitrification maintains the potability of fresh waters. Nitrate ions leached from the soil are eventually carried to the oceans. If denitrification did not take place, the earth’s supply of nitrogen, including atmospheric nitrogen, would and up in the oceans. Life would not be possible on land masses, except near the shores of oceans.
Loss of nitrogen by denitrification occurs during seasonal flooding of the land, or as a result of over irrigation of poorly drained land. Constantly wet soils have low concentrations of oxygen. This promotes the growth of nitrate reducing anaerobic species and denitrification, resulting in poor fertility of the soil.
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