Crop response to an unequal distribution of ions in space and time

Nutrient and salt ions often are unequally distributed in the root environment of plants and it will be expected that this strongly affect the plant reaction on the uptake of minerals and the osmotic potential. An unequal distribution of salts for example will be found with field grown crops in arid areas where the water supply is carried out by trickle irrigation (Meiri, 1984; Mmolawa and Or, 2000; Prichard et al., 1983). When under these conditions brackish water is used for irrigation, the salt accumulation on the soil surface of the dry areas between the emitters sometimes will be that strong that crystallization of salts occurs in the top layer whereby the surface is coloured white. Despite such tremendous local salt accumulations, crops often develop relatively quite well.