Farming in most of Mesopotamia was a challenge. Afterall, away from the banks of the Tigris and Euphrates Rivers, the region was mostly desert. The exception was the region in southern Mesopotamia where the Tigris and Euphrates deltas were. The delta region was covered with marshes and unbelievably rich soil. There, farming villages began to spring up and eventually gave rise to the first civilization - Sumer.
Irrigation in Mesopotamia
Even though the farmland of Sumer was so fertile, crops planted there still needed water, and rainfall in the area, even during ancient times, would have been very scarce. As a result, Mesopotamians developed a system of irrigation. In fact, the Mesopotamians became masters at controlling water. They had to drain marshy land to expose the rich soil, and they had to get water from the only source - the river(s) - to the crops.
Controlling water in Mesopotamia was no easy task. The land was flat, so Mesopotamian engineers had no real natural help from gravity in moving water without altering the terrain. Most water moving was done by canals. The canals then carried water from the river or the marsh to a reservoir where it could be stored until needed. More canals connected the reservoir to the farmland where it could be directed further to water the crops. Of course these networks of canals, channels, and reservoirs had to be maintained, and much of it had to be rebiult each year after the destructive floods ended.
Likely, the water from the marshes was not very good for growing crops because it was stagnate and salty. Some evidence suggests that the river water was slightly hard or salty also, and the buildup of that salt in the soil over centuries and millenia may have helped bring down the civilizations of Mesopotamia.
The Mesopotamians farmed all kinds of things, but the most valuable food sources were the grains they grew. Barley was probably the most common of these. Barley could be ground into flower for bread, made into soups, or fermented and turned into beer. They also grew common vegetables and gathered wild growing (and later domesticated) fruits such as figs and dates. The Mesopotamians had herds of livestock (cattle, goats, sheep) that could used for their meat, milk, and wool or hides.
Even though they were accomplished farmers and herders, the Mesopotamians also hunted wild game and caught fish from the river and sea. Grains, however, were the staple food of the Mesopotamians. Grain could be grown in abundance and packed the most punch in terms of nutrition and calories.