Legend

N:  No growing period in most years due to short length of growing period

S1: Single and short growing period, inadequate, supplementary irrigation is needed

S2: Single growing period, short, supplementary irrigation is desirable

S3: single growing period, adequate, for short-maturing crops

S4: Single growing period, adequate, for crops with medium cycle to maturity

S5: Single growing period, adequate for long-maturing crops

S6: Single growing period, adequate for long and very long-maturing crops. Less suitable for annual crops

D1: Two growing periods, neither is adequate, supplementary irrigation is necessary

D2: Two growing periods, neither is adequate, supplementary irrigation is desirable

D3: Two growing periods, the first can be considered adequate

D4: Two growing periods, both are adequate, for rain-fed crop production in most years, but double cropping is usually unfeasible because of interference between the two growing periods

D5: Two growing periods per year, of which both are adequate for crop production in most years. The second growing period is the most important

D6: Two growing periods, both are adequate. The first is important

D7: Two growing periods, both are adequate; including areas in which the two growing periods merge into a single long growing period