As civilisations became more dependent on a limited area of arable land they were forced to manage soil quality carefully. In the 8th century BC, the Greeks discovered that thrush droppings, when spread across a harvested field, could enrich the soil for the next crop. The Romans, concerned about the small amount of land available around the Mediterranean, became careful masters of their farm plots, practising mixed farming. They used 'fallowing', resting the land between harvests, to allow their animal herds to naturally fertilise the soil. The Roman statesmen, Cato the Elder, listed the most effective fertilisers as “...litter from stables, lupine, chaff, beanstalks, and the leaves of oak and holm-oak”.
