<P> Hesiod's Works and Days, 8th century BCE and Xenophon's Economy of the 4th century BCE provide information about working off the land . </P> <P> The olive harvest took place from late autumn to the beginning of winter, either by hand or by pole . They were placed in wicker baskets and left to ferment for a few weeks before being pressed . The screw press, although referred to as the Greek press by Pliny the Elder (XVIII, 37) was a late (2nd century BCE) Roman invention . Oil was preserved in terra cotta vases for use later . This was also the time for pruning of trees and vines and harvesting of legumes . </P> <P> Spring was the rainy season; farmers took advantage of this to bring fallow ground back into production . They practised biennial crop rotation, alternating from year to year between fallow and cultivated . Attempts to introduce triennial crop rotation with legumes in the third year, ran into problems due to the poor Greek soil, lack of power, and absence of mechanization . The Greeks did not use animal manure, possibly due to the low number of cattle . The only soil additive was weeds ploughed back into the ground after fields came out of fallow . </P> <P> In summer, irrigation was indispensable . In June, they harvested with sickles; the scythe was not used . Wheat was threshed with animal power; it was trampled by oxen, donkeys or mules, and the grain stored . Women and slaves ground it and made bread . </P>

When did the addition of the olive and the vine to wheat crops occur