Abstract:
Water scarcity is becoming a severe problem under arid and semi-arid regions. This water scarcity is due to increase in population growth and standards of living. These factors also affected negatively the availability of agricultural land and the reduction in water resources. Add to that the misunderstanding by the end users of the concept of soil-water-plant-atmosphere relationship. Therefore, it is a must to increase the water use efficiency and water productivity in agriculture, since irrigation of crops consume more than 75percent of the water resource in arid and semi-arid regions. In order to achieve the improvement of water use efficiency, and to meet the goal of high demand on food and fiber, it is important to model the relation between crop root distribution and extraction and evapotranspiration utilizing the weather data and the soil properties. The food and agriculture organization (FAO) had developed a computer model- CropWat (FAO, 1998) to calculate crop evapotranspiration based on Penman-Monteith modified equation and crop factor. This model takes into consideration deficit irrigation in general, but did not consider the root distribution and the absorption of the water among each segment of the root depth. An experiment was carried on during the growing season of 2007 and 2008 on potato, and peppers, where the roots were partially filled to field capacity i.e. the roots depth was divided into four parts 25percent each part. The water treatments were fill the first quarter from the top to field capacity, fill the top 50percent of the root to field capacity, fill the top 75percent to field capacity and last treatment which the control fill the whole root zone to field capacity. Results indicates and will be presented that the 50percent treatment gave significant and higher total yield and marketable yield than the other treatments for bothcrops. Also water saving was significantly higher in the 50percent treatment, and so the water use efficiency and the water productivity.