The Impact of Seawater Salinity on Evapotranspiration and Plant Growth Under Different Meteorological Conditions

Conventional water resources of good quality are scarce especially in arid and semiarid regions. The salinization of soils and water places is a substantial constraint of crop productivity. The mixed application of fresh water along with seawater is becoming a common practice by the farmers near sea sides in the developing countries. Seawaters contain beneficial nutrients that can be useful for plants. The use of saline water has shown a considerable importance for crop production in the recent years. Unfortunately, the misuse of saline water for irrigation may increase soil salinity to a level higher than the tolerance of crops. The proper use of brackish water appeared to be reasonable with certain conditions. Hamdy et al. (2005) found that freshwater can be substituted to some extent with saline water without any loss in production especially in water deficit areas. Moreover, Oron et al. (2002) reported that high saline water has an agricultural potential with proper irrigation management. Petersen (1996) observed that the higher volume of irrigation water reduced soil salinity and transported salts below the root zone. Whereas, Ghadiri et al. (2005) noticed restricted water uptake by salinity due to the high osmotic potential in the soil and high concentrations of specific ions that may cause physiological disorders in the plant tissues and reduce yields. Irrigation water, drainage salinity and evaporation are interconnected terms. Any increase or decrease in one of them will affect others. More irrigation water enhances leaching of salts, decreasing soil salinity and increasing drainage water salinity. Furthermore, evaporation and salt accumulation are also positively connected, hence increasing salinity of applied water and high evaporation lead to high concentration of salts in drainage water. Soil evaporation is mostly affected by environment factors, which includes mainly two aspects: climate aspect (net radiation, wind speed, air temperature, etc) and soil aspect (soil types, soil water content and temperature, hydrological properties, soil salinity, etc). In general, the soil water is considered as a direct factor affecting evaporation process. In fact, the surface temperature may be considered as the indirect factor on soil evaporation (Zhu & Takeo, 2010).