Impact of Water Quality and Drip Irrigation On Tomato Yield In Sandy Calcareous Soils Amended with Natural Conditioners.

The scientifically applied research program related to water saving, conservation and salinity in agriculture is essential, where agricultural activities account for more than 90% of the total water consumed in Saudi Arabia. The purpose of this study was to investigate the effect of irrigation (levels & methods) and type of natural conditioners (organic matter and clay deposit) on tomato yield, water use efficiency (WUE) and the distributions of soil moisture and salts in the root zone of sandy calcareous soils. Field and greenhouse experiments were conducted at the College Experimental station in 2005-2008 seasons. It consists of clay deposits at a rate of 2.25% and organic manure at rate of 1.25%, three irrigation water applied levels, using surface and subsurface drip irrigation. Two source of water was used in the experiment, well water with electrical conductivity (EC) of 3.6 dS/m well above the threshold value of ECw for tomato and water with ECw of 0.86 dS/m. The results showed a significant decrease in yield with saline water in the second season at the open field experiment. However, the yield was less affected in greenhouse experiment mainly because of the leaching practices prior to planting in the second season and the use of fresh water at the early stages of the growth. Results also indicated that yield was significantly increased with the increase of irrigation level, whereas WUE significantly decreased with increase of irrigation level. The differences between surface and subsurface drip on yields and WUE were also significant. Results indicated that moisture content of subsurface treated layer increased dramatically, while salts were accumulated at the surface and away from the emitters in subsurface drip irrigation.