Figure 8.4 shows the present cultivation calendar, which is adapted to the
situation existing today. The cultivation of cotton extends over three normal
cultivation periods because of its long vegetation period. Quite frequently,
prior to the cultivation of cotton, bersim or beans are grown since these im-
prove the soil through nitrogen fixation. The water requirements of the dif-
ferent crops grown in Egypt today vary greatly (see Table 8.5). The Egyptian
Ministry of Irrigation’s planning is based on them. The annual water demand
for irrigation in the Nile valley is currently calculated at about 50 billion m3
,
giving each feddan on average about 7,000 m3
 of water for that purpose.