علوم و مهندسی آبیاری (Sep 2019)
Study on the Effect of Deficit Irrigation Composing with Controlled Vegetative on Date Palm Seedlings (CV. Barhee)
Abstract
The world population today is about 6.5 billion, and it is estimated that it will increase to 9.1 billion by the year 2050 (UN, 2004). It is estimated that irrigation consumes more than 80% of the good quality water. Due to the reduction in available water resources, the application of water-saving strategies, such as deficit irrigation and the use of underground water resources, can reduce water usage for irrigation. One strategy for the source control is to restrict the outflow in field drains such that the height of the water table is maintained at a shallow depth that allows certain crops to utilize groundwater to satisfy a portion of their water requirements. Shallow groundwater can be a significant source of water for agricultural production, especially during the drought period. The fraction of the crop water demand that can be met by shallow water tables depends on the crop grown, irrigation and drainage management, the soil type, the depth to the water table, and the shallow groundwater salinity(Ayars et al. 2006). A wide range of crops has been successfully grown that obtained a significant portion of the crop water requirement from shallow groundwater. The types of crops range from truck crops (pepper and carrots) to grain, hay, and some tree crops (e.g. date palm) that have salt tolerances from sensitive (lettuce) to tolerant (cotton). Although such observations have been made for moderately salt-tolerant perennial crops, such as alfalfa hay, vine and tree crops have a larger potential for in- situ water use from shallow groundwater than do annual crops because of their well-developed and established root system after the first growing season. Hutmacher et al. (1996) showed that cotton (Gossypium hirsutum L.) crops can obtain 20 to 50% of their water requirement from shallow groundwater under the proper irrigation management. The timing and amounts of surface irrigation impact the extent to which crops will utilize shallow groundwater. Judicious use of deficit irrigation in combination with shallow groundwater management is necessary to achieve optimal results (Ayars et al., 1999).
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