Irrigation Control of Container Crops by means of Tensiometers

The problem of water shortage and water quality becomes more and more important year-by-year, for consumption increasing and good water availability reduction. The activities that need elevated water amount, like the cultivation of ornamental and horticultural crops, suffer from this situation and, consequently, new solutions have to be introduced to rationalize water consumption, avoiding water shortage periods and water quality worsening (e.g. increasing water salinisation). The usual practice of irrigation for container crops does not take into account the exact plant water requirements, entrusting the control to simple systems like timers. The detection of water potential in pots, by means of tensiometers or other similar tools, is one of the possible techniques to adapt water supply to real plant exigencies, reducing the consumption, without negative effects on the plants. The aim of this work was to study the adequacy of tensiometers to control irrigation of two shrub species (Cupressus and Cornus), with different water demand, cultivated in container with drip irrigation. Field experiments were preceded by laboratory studies to compare different tensiometers and to define system settings, sensor location in respect to trickler, volumes and duration of irrigation events. The results obtained from laboratory and field experiments demonstrated the possibility to optimise water use using automatic systems based on soil moisture sensors.