Rainfed regions are those where crop production is exclusively dependent upon rainfall. Rainfed
agriculture plays an important role in Pakistan’s economy and makes 17 percent of the total crop growing area
in the country. Pakistan rainfed regions cover Potohar and Balochistan plateau and they exist in different
climatic zones (extremely arid to very humid). Water balance (difference between rainfall and evapotranspiration)
of both plateaus calculated of two crop growing season i.e. Rabi (October to April) and Kharif (May to
September). FAO-modified Penmen Monteith method was employed to calculate reference crop
evapotranspiration by using different climatological data from 1931 to 2008. The results drawn during 1961-1990,
which shows that, the conditions for sowing of seasonal crops were relatively more favourable in both plateaus.
i.e.Potohar (Rabi and Kharif) and Balochistan (Rabi). Annual water deficit was 4.3mm/month and 111mm/month
for Potohar, Balochistan plateaus respectively and now it has further increased due to increase in
evapotranspiration. During 1991-08, conditions are replicating, as it was 1931-60 while during some months of
the year, the situation has become worse especially in Balochistan during Kharif season. Water surplus has
improved during December while water deficit has increased during March. In potohar plateau, water surplus
has significantly increased during June (Kharif) due to increase in rainfall. Monthly Probability of occurrence
of rainfall for both plateaus was also calculated for better crop planning and water management. By analysis
the probability and water balance map, It is recommended that Rabi crops especially wheat may be sown during
mid of November rather than December in Balochistan plateau. Proper preservation of rainfall water during
December to February may help to overcome the water stress in the coming summer months in both plateaus.
Cultivation of Kharif crop is not recommended in Balochistan plateau unless proper preservation of water loss
from evapotranspiration.