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Nitrates

Nitrates are used widely in farming as fertilizer. Unfortunately, a major environmental problem associated with agriculture is the leaching of nitrates into the environment. Possible sources of nitrates that would, in principle, be available indefinitely, include:

The last option was proposed in the 1970s, but is only gradually becoming feasible. Sustainable options for replacing other nutrient inputs such as phosphorus and potassium are more limited.

Other options include long-term crop rotations, returning to natural cycles that annually flood cultivated lands (returning lost nutrients) such as the flooding of the Nile, the long-term use of biochar, and use of crop and livestock landraces that are adapted to less than ideal conditions such as pests, drought, or lack of nutrients. Crops that require high levels of soil nutrients can be cultivated in a more sustainable manner with appropriate fertilizer management practices.