AUTOMATIC IRRIGATION BY USING SOIL MOISTURE SENSOR IN VERTICAL CLOSED SYSTEM FOR LETTUCE PRODUCTION

Abstract

The experiment was held at the Arid land Agricultural graduate studies and Research Institute - Ain Shams University. A soil moisture sensor is designed and used for measuring and controlling soil moisture content in plant media. The device has been programmed and connected to three water-lifting pumps to operate them according to each treatment. A vertical system has been constructed using 18 columns of white square styrofoam pots filled with perlite (In-organic substrate). Three soil moisture content treatments were selected as T1 = 60 %, T2= 80%, and T3 = 100% which were controlled by the sensors. Solution tank filled with dissolved nutrient elements was used for supplying required water. Two types of lettuce (green and red) lettuce seedlings were planted in the perlite substrate and irrigated by drip irrigation system. The system was closed and was based on smart automatic drip irrigation system, Results revealed that, 556.5 liters of water was consumed under condition of T1 = 60 %, while 697.5 liters and 908.5 were consumed under condition of T2= 80 %, and T3 = 100% respectively After 47 days the Red lettuce yield (weight, number of leaves, and also weight of dry lettuce) was higher than green lettuce for all treatments. Yields of lettuce per system unit (4.5 m2) 16 kg/m2 and water use efficiency 26kg /m3 (Barbosa et al 2015) conventional production yielded 3.9 ± 0.21 kg/m2/y of lettuce produce, with water. Hydroponics offered 11±1.7 times higher yields but required 82±11 times more energy compared to conventionally produced lettuce.