ABSTRACT
Hydrologic budget analyses can be used to estimate the amount of water in the root zone and extent of deep drainage on a day-to-day or weekly basis, providing water is applied uniformly to the land surface by rainfall, sprinkler irrigation, basin irrigation, or furrow irrigation. The evaporative demand is the potential crop water use and provides an indication of the level of water supply that annual crops need in the middle of their season of active growth if they are to achieve potential productivity. Climate, which is based on averages of weather variables over years, determines the types of crops, cropping systems, and management methods that are optimal. The temperature difference is normalized against the vapor pressure deficit of the air, measured under standard conditions of solar radiation, and must be calibrated for the specific crop species and climatic zone. Optimal crop cycle lengths were estimated for the Savanna and Sahelian zones using a hydrologic budget method.
