A young tree requires about 15 to 20 litres of water weekly during the first growing season. The irrigation required by a tree, i.e. the amount of water applied at a specific time and the frequency of irrigation, is influenced by the following factors: the age and size of the trees, the season and growth stage, the crop size (affecting crop factors), rainfall, temperature, relative humidity, and wind (affecting evaporation), soil texture, structure and depth (affecting soil water holding capacity, infiltration and percolation rate), and the type of irrigation system. Double line drippers or microsprinklers, where the system has been designed by experts, are used with success by olive growers locally. A range of apparatus is available today to help optimise irrigation scheduling.