agriculture sustainability?

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Question by paperkite: agriculture sustainability?
With each crop, we diminish the soil content in various minerals and compounds. Some of these minerals never come back to the ground. Most of them go into the cities sewage systems. If nothing is done then the quality of food (taste included) will continue to decrease and some plants won’t even grow. Artificial fertilizers are not (by far) a complete solution since they cannot contain all the missing substance. Organic residues from sewage are polluted by detergents , chloride and other chemicals so they can’t be used / transformed into fertilizers.
What are the choices we have for a sustainable agriculture? Thanks!

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