Irrigation with brackish water under desert conditions III. Methods for achieving good germination under sprinkler irrigation with brackish water

Abstract

Conventional sprinkler irrigation methods used in a Mediterranean desert climate include pre-irrigation to wet the rooting zone of the soil profile to field capacity, followed by light irrigation daily during the germination period, and thereafter by the irrigation schedule appropriate for the crop and season. When brackish water is used under the high-evaporation conditions of the desert summer, the light daily irrigations during the germination period result in rapid salinization of the seedbed and in very poor germination. However, in soils with high water infiltration rates, these problems can be averted by omitting pre-irrigation, and applying all the water thus saved for leaching of the seedbed during the germination period. In a field experiment with tomatoes, the application of 215 mm brackish water (EC i = 4.4 dS/m) during a 10-day period after sowing on a flat soil surface resulted in an effective leaching of salt from the upper 5 cm soil layer and in a five-fold increase in the number of germinated seedlings compared to the conventional method of irrigation with the same water. When brackish water was used with the conventional irrigation schedule, sowing in shallow furrows tripled the number of germinated seedlings compared to sowing on a flat seedbed, and the use of a mulch of wood chips quadrupled the number of germinated seedlings compared to no mulching.