Farming in Egypt involved the use of irrigation. The river Nile was the source of water for the region and the fields were “watered by foot,” meaning they were watered by the effort of those who either carried the water or dug the irrigation ditches.
But the Promised Land was not like the land of Egypt. It was not a huge plain watered from a river, but a land of hills and valleys, fed by the rains of heaven. It was a land that the Lord Himself would water and care for; therefore, the people would need to focus on obeying and worshiping Him in order for their fields to prosper.
The Lord wanted to raise up a people that would learn to completely depend on Him. He sought a people that would look to Him to supply all their needs. They were not to trust a land, or a river, nor their own ingenuity for irrigation, but the Lord.
The Lord still seeks those who will fully trust Him.