Agriculture was the main economic activity in ancient Mesopotamia. Operating under tough constraints, notably the arid climate, the Mesopotamian farmers developed effective strategies that enabled them to support the development of the first known empires, under the supervision of the institutions which dominated the economy: the royal and provincial palaces, the temples, and the domains of the elites. They focused above all on the cultivation of cereals (particularly barley) and sheep farming, but also farmed legumes, as well as date palms in the south and grapes in the north.
There were two types of Mesopotamian agriculture, corresponding to the two main ecological domains, which largely overlapped with cultural distinctions. Southern or Lower Mesopotamia, the land of Sumer and Akkad, which later became Babylonia received almost no rain and required large scale irrigation works which were supervised by temple estates, but could produce high returns. Northern or Upper Mesopotamia, the land that would eventually become Assyria, had enough rainfall to allow dry agriculture most of the time so that irrigation and large institutional estates were less important, but the returns were also usually lower.
Climate While developing models to describe the early development of settled agriculture in the Near East, reconstructions of climate and vegetation are a subject of consideration. During the glacial period, it is thought that lower temperatures or higher aridity resulted in sparse or non-existent forest cover similar to steppe type terrain in the area of the Zagros Mountains and varying forest cover in the territories of modern-day Turkey and Syria. Northwest Syria, dominated in ancient times by deciduous oak, is thought to have been less arid between 10,000 BCE and 7000 BCE than it is today. Scholars believe that wild cereal grasses probably spread with the forest cover, out from the glacial refugia westward into the Zagros.
Topography
The societies of ancient Mesopotamia developed one of the most prosperous agricultural systems of the ancient world, under harsh constraints: rivers whose patterns had little relation to the growth cycle of domesticated cereals; a hot, dry climate with brutal interannual variations; and generally thin and saline soil. Conditions in the north may have been more favourable because the soil was more fertile and the rainfall was high enough for agriculture without irrigation, but the scale of rivers in the south and the flat plains which made it easy to cut irrigation channels and put large areas under cultivation gave advantages to the development of irrigated farms which were productive but required constant labour.
The native wild grasses in this region were densely growing, highly productive species, especially the varieties of wild wheat and barley. These grasses and wild legumes like pea and lentil were used as food sources in the hunter-gatherer societies for millennia before settled agriculture was widespread.
Rivers The two main watercourses of Mesopotamia, which give the region its name, are the Euphrates and the Tigris, which flow from Anatolia to the Persian Gulf.F. Joannès, "Tigre" & "Euphrate" in The Euphrates is around 2,800 km long and the Tigris is about 1,900 km. Their regime is of the pluvial-naval type, with high flow in spring as a result of melting snow and when rains fall in Upper Mesopotamia. This is more accentuated with the Tigris, which receives several tributaries from the Zagros during the second part of its course, while the Euphrates has only a minor tributary in Upper Mesopotamia. Thus its output is weaker, especially since it crosses flatter areas and has a wide bend in Syria which slows its flow. Floods of the rivers thus take place in spring—in April for the Tigris and in May for the Euphrates (shortly after or during the harvest). Their baseflow occurs in summer at the time of greatest heat, when evapotranspiration is very high, especially in the south. The variability of flow rate over the year is very great—up to 4:1. The discharge of the Euphrates and its floods were weaker than those of the Tigris, so it was on particularly on its banks that agricultural communities of southern Mesopotamia focused. In this region, the ground is very flat, leading to bifurcation, which results in islands and marshes, as well as sudden changes of course, which occurred several times in antiquity. Both rivers carry silt which raised them above the level of the surrounding plain, making it easy to irrigate the land surrounding them. However, it also meant that their floods had the potential to cause serious damage and could cover a vast area. The flatness of the region also meant that the phreatic zone and the stream bed were very close, causing them to rise in periods of flooding. In modern times, the Tigris and the Euphrates join to form the Shatt al-Arab which then debouches in the Persian Gulf, but in antiquity, their delta did not reach so far south, because it was created slowly by the deposition of alluvium.P. Sanlaville, "Considérations sur l'évolution de la Basse Mésopotamie au cours des Derniers millénaires", Paléorient 15/2, 1989, p.5-27.P. Sanlaville & R. Dalongeville, "L'évolution des espaces littoral du Golfe Persique et du Golfe domain Depuis la phase finale de la transgression post-glaciaire", Paléorient 31/1, 2005, pp. 19-20
Other watercourses in Mesopotamia are the rivers that flow into the Tigris and Euphrates. The tributaries of the former originate in the Zagros; from north to south they are the Great Zab, the Little Zab, and Diyala. Their courses have a rapid flow, on account of the steep relief and the gorges through which they flow, as well as the snowmelt in spring which leads to large floods in April/May. They carry a large amount of the alluvium which ends up in the Tigris. The Euphrates has two tributaries which meet it in southern Jazirah: the Balikh and the Khabur.
Relief
The terrain of Mesopotamia is mostly flat, consisting of floodplains and plateaus. It is bordered by high mountains on the eastern side—the Zagros range, which is pierced by deep valleys and canyons with a northwest-southeast orientation (Great Zab, Little Zab, Diyala)—and by smaller mountains and volcanoes in Upper Mesopotamia (Kawkab, Tur Abdin, Jebel Abd-el-Aziz, Sinjar, Mount Kirkuk). Essentially, Upper Mesopotamia consists of plateaus which are slightly inclined to the east, rising from 200–500 m in altitude, and which are now known as Jazirah (from the Arabic, al-jazayra, 'the island'). Thus, the rivers flow through valleys which are 1–10 km wide. The southern half of Mesopotamia, which is the part properly called Mesopotamia from a geophysical point of view, since it is where the Tigris and Euphrates flow close to one another, is a vast plain, which is 150–200 km wide and has only a very slight incline, decreasing to the south until it is nearly non-existent. This encourages the development of river braiding, sudden changes of course, and the establishment of marshy areas.
Soil The soil in Mesopotamia is mostly of the sort that is normal in arid climates: a shallow layer on top of the bedrock which is not very fertile. They are generally composed of limestone or gypsum with nutritive elements which enable plant growth, but have only a narrow layer in which the roots can grow. Deeper soil is found in the valleys and culverts of Upper Jazirah. In the more arid areas of Lower Jazirah and Lower Mesopotamia by contrast, the soil is generally sparse and very shallow (solonchak and fluvisol types) and mostly composed of gypsum. They degrade easily and irrigation accelerates both their erosion and their salinisation. However, the poverty and fragility of the soils of Southern Mesopotamia are largely compensated for by sheer area of flat land available for irrigation. In the north by contrast, there is better soil, but less land and there is more risk arising from the variation in precipitation.
Human infrastructure Mesopotamian farmers did a number of things in order to augment the land's potential and reduce its risks. The infrastructure that they created profoundly altered the land, particularly through the creation of irrigation networks in the south where the supply of water from the river was necessary for the growth of the crops. Thanks to textual sources it is partially possible to reconstruct the appearance of the Mesopotamian countryside and the different types of land exploited by the farmers.
Irrigation
The first archaeological signs of irrigation in Mesopotamia appear around 6000 BC at Choga Mami in central Mesopotamia, during the Samarra culture (6200-5700 BC). Mesopotamia south of this site is very poorly attested in this period—it is possible that the first communities developed there at the same time and also made use of irrigation. Survival was only possible with the use of an irrigation system, since without it the viable agricultural area in this region was limited to the banks of the two great rivers. Canals were cut to bring the water that was needed for the plants to grow to the fields, but also to divert water and thus limit the damage from floods. When the water level was high, the larger canals became navigable and could be used for trade and communication. Irrigation was also adopted in areas where it was not absolutely necessary, in order to increase yields. Communities and rulers made the maintenance, repair, and dredging of irrigation infrastructure one of their highest priorities.
The water for irrigation was brought to the fields by canals.M. Sauvage, 'Canal,' in The largest of these were fed directly from the rivers and supplied water to smaller canals which supplied yet smaller channels, all the way down to small irrigation ditches. The system could also include raised canals and sometimes aqueducts, if the terrain required them. Some regulating mechanisms were in place to control the flow and the level of the water, such as closeable basins. The sediment carried in the rivers meant that their beds were higher than the fields on the floodplain, so the water could be brought to the fields using gravity alone, once a ditch had been cut in the side of the riverbank.F. Joannès, "Irrigation", in However, mechanisms for raising water, like the shadoof and the noria, were in use from the first millennium BC. In some regions irrigation could also be effected from wells.
The irrigation network of Mari is well known from descriptions on small tablets from the first half of the 18th century BC relating to maintenance work and thus provides a useful case study. The tablets mention the 'mouth' (KA/pûm) where the water from the river entered the canal and deposits of clay had to be removed. The basic structure at this level was the muballitum, a mechanism which controlled the flow of water from the river and thus the water level of the canal. It was a barrier made out of wooden piles (tarqullum), reinforced with bundles of reeds and brush. The main canals (takkīrum) are distinguished from the minor calls (yābiltum) which flow from them. Valves (errētum) on the sides of the canals allowed water to be let out if the level rose too high. Ditches (atappum) were located at the end of the canal. Dams (kisirtum) were used to store water. Secondary basins were fed by terracotta pipes (mašallum). Maintenance of the canal was very intensive work: according to one letter, the governor of the district of Terqa had to mobilise nearly 2,000 men for the task and it seems that this force proved insufficient.See the dossier in J.-M. Durand, Les Documents épistolaires du palais de Mari, Volume II, Paris, 1998, p. 572-653.B. Lafont, "Irrigation Agriculture in Mari", in .
Fields and land division