Is this source a reliable description of the engineering methods of the Inca? As soon as the Incan 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 constructed. The engineers showed great cleverness and skill in supplying water for the crops, since only scattered sections of the land could grow corn. For this reason, they endeavored to increase its fertility as much as possible.