the soils, produced by poorly drained irrigation, had been reducing yields of wheat in the southern part of the country, leading to the conversion to more salt-tolerant barley growing. Urban populations there had peaked already by 2,600 BC, and demographic pressures were high, contributing to the rise of militarism apparent immediately before the Akkadian period (as seen in the Stele of the Vultures of Eannatum). Warfare between city states had led to a population decline, from which Akkad provided a temporary respite. It was this high degree of agricultural productivity in the south that enabled the growth of the highest population densities in the world at this time, giving Akkad its military advantage. The water table in this region was very high and replenished regularly—by winter storms in the headwaters of the Tigris and Euphrates from October to March and from snow-melt from March to July. Flood levels, that had been stable from about 3,000 to 2,600 BC, had started falling, and by the Akkadian period were a half-meter to a meter lower than recorded previously. Even so, the flat country and weather uncertainties made flooding much more unpredictable than in the case of the Nile; serious deluges seem to have been a regular occurrence, requiring constant maintenance of irrigation ditches and drainage systems. Farmers were recruited into regiments for this work from August to October—a period of food shortage—under the control of city temple authorities, thus acting as a form of unemployment relief. Gwendolyn Leick has suggested that this was Sargon's original employment for the king of Kish, giving him experience in effectively organising large groups of men; a tablet reads, "Sargon, the king, to whom Enlil permitted no rival—5,400 warriors ate bread daily before him". Harvest was in the late spring and during the dry summer months. Nomadic Amorites from the northwest would pasture their flocks of sheep and goats to graze on the crop residue and be watered from the river and irrigation canals. For this privilege, they would have to pay a tax in wool, meat, milk, and cheese to the temples, who would distribute these products to the bureaucracy and priesthood. In good years, all would go well, but in bad years, wild winter pastures would be in short supply, nomads would seek to pasture their flocks in the grain fields, and conflicts with farmers would result. It would appear that the subsidizing of southern