Abstract:
The high variability of rainfall has serious impacts on food security in the world. Knowledge of crop water requirement is vital in agriculture for designing and managing irrigation and drainage systems. This research was, therefore, conducted to compare between sorghum (Sorghum bicolor (L.) Moench) crop water requirements and effective rainfall and their effect on yield and water productivity. Arfaa Gadamk variety (2009/10, 2010/11 and 2011/12) under the dry-land farming of Gedaref State during three consecutive seasons was used. Mean annual rainfall (mm), measured within the three rainy seasons, and collected crop data were plant population, plant height at flowering, dry matter, 1000- seeds weight, grain yield and water productivity (kg/m3). Mean rainfall was 483.7, 568.3 and 284.5 mm while the crop water requirement was 443, 462.5 and 462.4 for season one, two and three, respectively. Result showed that the effective rainfall was below the crop water requirements for the third season. The highest grain yield (1864.7 kg/ha) for sorghum was produced in season two and lowest (1619 kg/ha) was produced in season three. The highest value of water productivity 0.5 kg/m3 for sorghum was produced in season one and the lowest 0.45 kg/ m3 in season three. The main recommendation was the possibility for early sowing date by using of climate forecasts instead of historical data in selecting planting dates. Also, the government and development partners should consider increasing investments in construct and maintain rain-water harvesting (RWH) structures to ensure supplemental irrigation during critical stages.
