Beneath the lookout and above the Guards’ Quarters [1] are agricultural terraces that face the sun year-round and were used to grow multiple crops.
In 2002, Cusqueñan archaeologist Elva Torres took samples from different terraces to determine what crops the Inca cultivated in Machu Picchu [2]. The results showed that they cultivated pumpkins, squash, tomatoes, peppers, and other indigenous tubers, such as yacon, which is used to treat diabetes.
Links:
[1] http://www.moon.com/destinations/peru/machu-picchu/ruins-tour/guards-quarters
[2] http://www.moon.com/destinations/peru/machu-picchu