Since ancient times, farmers have viewed the soil as a source of wealth to preserve and as an indicator of environmental health. For example, the Roman writer and politician Marcus Porcius Priscus (234-149 BCE), better known as Cato, noted in his famous essay “De Agri Cultura” many usual agricultural practices carried on vineyards and olive trees. One of them is particularly interesting: ancient Rome farmers used to grow a crop named Ocimum (many authors think that this was the name given to vetch,Vicia sp.), which was planted between the tree lines but turned under the soil as green manure before seed set.' At that time, they did not know ?1 about carbon content in soil or carbon balance, but these kinds of practices said much about their senseof keeping the soil accounts in order—I will return to this point later.
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