What specific farming and building techniques were used by the Incas?

As soon as the Inca ruler had conquered any kingdom and set up his government, he ordered that the farmland used to grow corn be extended.

For this purpose he ordered irrigation channels to be construed.

The engineers showed great cleverness and skill in supplying water for the crops, since only scattered sections of the land cold grow corn.

For this reason, they endeavored to increase its fertility as much as possible.