Water balance and fertigation for crop improvement in West Asia. Results of a technical co-operation project

Mediterranean countries have a severe shortage of water resources for agricultural, municipal and industrial purposes. This situation is aggravated daily due to the rapidly increasing population in the area. Agriculture is the biggest consumer of water with about 80% of the renewable resource used for irrigation. Traditional irrigation methods are highly inefficient: only about one-third of the applied water is actually transpired by the crops. Clearly, there is great scope for improved irrigation management. Intensification of agricultural production to meet growing market demand requires the simultaneous application of irrigation water and fertilizers. Application of fertilizer in drip irrigation (fertigation) is an effective way to promote efficient use of these scarce and expensive resources. There is widespread interest in Mediterranean countries in fertigation. Nevertheless, information on the form and concentration of the nutrients required for different crops is presently inadequate. Moreover, the low fertilizer recoveries due to extensive fertilization practiced during the last few decades have created serious agricultural and environmental problems. High nitrate concentrations in groundwater and deterioration of some important quality parameters of agricultural products are the main concerns. Recognizing the potential role of nuclear techniques in identifying improved water and fertilizer management practices, the IAEA implemented two regional technical co-operation projects during the period 1995-2000 with eight participating countries from the West Asia region: The Islamic Republic of Iran, Jordan, Lebanon, Saudi Arabia, the Syria Arab Republic, Turkey, United Arab Emirates and Yemen. The main objective was to establish water balance and fertigation practices using nuclear techniques, with a view to improving crop production in arid and semi-arid zones. The projects aimed to compare the following parameters under conventional fertilizer and water management practices with fertigation: Crop yields, N fertilizer recovery, Water use efficiency and crop water requirements, and Nitrate leaching. Water use and N-fertilizer efficiency under drip irrigation compared with conventional agricultural practices were estimated using neutron probe and 15N recovery techniques, respectively