Effect of Trickle Irrigation Intervals on Distribution and Utilization of Soil Moisture in a Vineyard

Abstract

In an established vineyard on sandy clay soil the effect of trickle irrigation interval on soil moisture and salt distribution and relative water use efficiency was examined. The distribution of soil moisture and salinity resulting from this irrigation method is two dimensional, with moisture contents high along and beneath the row and decreasing laterally. The main active soil layer supplying water to the roots was found to be restricted to a strip approximately 2 m wide and 120 cm deep beneath the rows, whereas the total distance between rows was 3 m. The effect of shorter irrigation intervals, with proportionally smaller amounts of water applied in a single irrigation, was to decrease the variations of moisture content in the root zone and establish a continuously higher moisture regime. Salts were concentrated in a surface pocket and a deep layer with a leached zone between them. The relative position of the concentration layers was determined by the amount of water applied in a single irrigation. Relative water use efficiency was positively affected by shorter irrigation intervals both in terms of grape (Vitis vinifera L. ‘Tamar’) production and of weight of prunings.