COMBINING SOIL MOISTURE CAPACITANCE PROBES AND WETTING FRONT DETECTORS TO STEER IRRIGATION SCHEDULING IN A COMMERCIAL CHERRY TREE FIELD LOCATED IN THE EBRO VALLEY (NE SPAIN)

This work describes a real case in a commercial cherry tree orchard located in a semi-arid region (Ebro Valley, NE Spain) during the 2011 growing season. Electrical conductivity (EC_w) of the irrigation water was measured weekly and ranged from around 1 dS/m to slightly above 2,5 dS/m. At the same time that EC_w was measured, two Fullstop^® (Agriplass, South Africa) Wetting Front Detectors (WFD) buried at 30 and 60 cm depth under the dripper were sampled. The EC from the sampled solution collected at 30 cm (EC₃₀) followed the same trend as EC_w, but salts were consistently more concentrated (EC₃₀ ranged from 1,5 dS/m to 4,5 dS/m). At 60 cm there was less water moving down and the salts concentrated even more, with EC₆₀ ranging from 2,5 dS/m to 5 dS/m. Soil moisture (m³/m³) was monitored at three depths (15, 35 and 50 cm), using capacitance probes (Model 10HS, Decagon Devices Inc, USA). Irrigation was applied daily from early March to October, with the goal of maintaining soil moisture around field capacity (Full Point) and pushing salts below 30 and 60 cm (avoid salt build up in the rooting zone), despite of the seasonal increase of ECw.