Automated Irrigation Management of Organic Greenhouse Tomatoes

This research investigated the effects of different irrigation schedules and mulching in greenhouse organic tomatoes grown using an automated irrigation system based on root zone soil moisture sensors. Two consecutive short cycle crop productions were conducted in a polyethylene greenhouse at Ege University, Bornova-Izmir, Turkey. Full irrigation (no stress) in which soil water content was allowed to be depleted to 20% in the plant root zone and two deficit irrigation treatments in which soil water content was allowed to be depleted to 35% (Deficit 1) and 50% (Deficit 2) of the available water content in the plant root zone were tested using sensor technologies and compared with and without mulching. An irrigation controller was installed in each irrigation treatment and the soil moisture was controlled and monitored with a theta-probe sensor installed at 15 and 45 cm soil depth. According to the overall results of two crop cycles, mulching did not statistically affect the yield. The highest yield was obtained from the full irrigation treatment with and without mulching in both cycles. Recorded total amount of irrigation water in fall and spring growing cycles were the highest in full irrigation treatments at 122 and 334 mm, respectively. Higher water consumption was determined in unmulched treatments in both growing seasons. Mulches achieved water savings of between 12 and 18%. Water consumption of tomato plants decreased with the increase of deficit levels. It was concluded that soil water content in loamy soils can be allowed to be depleted to 35% of the available water content in the plant root zone for irrigation management in tomato production under waterscarce situations, without significant decrease in yield.