540 kg/ha, Greece at 620 kg/ha. This makes the Mediterranean very difficult to average over all. An agricultural unit was known as a latus fundus mentioned by Varro as a great estate, which can be interpreted as a latifundia or at 500 iugera or around 125 hectares because this is the land limit imposed by Tiberius Sempronius Gracchus as tribune in 133 BC. With the incorporation of Egypt into the Roman empire and the rule of the emperor Augustus (27 BC-14 AD), Egypt became the main source of supply of grain for Rome. By the 70s AD, the historian Josephus was claiming that Africa fed Rome for eight months of the year and Egypt only four. Although that statement may ignore grain from Sicily, and overestimate the importance of Africa, there is little doubt among historians that Africa and Egypt were the most important sources of grain for Rome. To help assure that the grain supply would be adequate for Rome, in the second century BCE, Gracchus settled 6,000 colonists near Carthage, giving them about each to grow grain. Grain made into bread was, by far, the most important element in the Roman diet. Several scholars have attempted to compute the total amount of grain needed to supply the city of Rome. Rickman estimated that Rome needed 40 million modii (200,000 tonnes) of grain per year to feed its population. Erdkamp estimated that the amount needed would be at least 150,000 tonnes, calculating that each resident of the city consumed of grain per year. The total population of Rome assumed in calculating these estimates was between 750,000 and one million people. David Mattingly and Gregory Aldrete estimated the amount of imported grain at 237,000 tonnes for 1 million inhabitants; This amount of grain would provide 2,326 calories daily per person not including other foods such as meats, seafood, fruit, legumes, vegetable and dairy. In the Historia Augusta, it is stated Severus left 27 million modii in storage - considered to be a figure for the canon at the end of the 4th century and enough for 800,000 inhabitants at 500 lbs of bread per person per annum Pliny the Younger painted a picture that Rome was able to survive without Egyptian wheat in his speech the Panegyricus in 100 AD. In 99 there was an Egyptian crisis due to inadequate flooding. Pliny the Younger stated that for "long it was