EFFECT OF DRIP IRRIGATION FREQUENCY ON SOIL MOISTURE DISTRIBUTION AND WATER USE EFFICIENCY FOR SPRING POTATO PLANTED UNDER DRIP IRRIGATION IN A SANDY SOIL

Abstract

The current study was carried out at Agricultural and Veterinary Research Station, Faculty of Agriculture and Veterinary Medicine, Qassim University, Kingdom of Saudia Arabia during 2003 and 2004 spring growing seasons. The objective of this study is to investigate the effect of irrigation frequency on irrigation water depth d, wetted area width W and depth D, potato root distribution, soil moisture distribution, water losses by deep percolation, potato tuber yield and water use efficiency. Treatments consisted of seven different drip irrigation frequency: IF2/1 (irrigating every half day), IF1/1 (irrigating every day), IF1/2 (irrigating every 2 days), IF1/3 (irrigating every 3 days), IF1/4 (irrigating every 4 days), IF1/6 (irrigating every 6 days) and IF1/8 (irrigating every 8 days). All treatments received the same total amount of drip irrigation water. The results indicated that drip irrigation frequency affected all parameters of this study. Irrigation water depth d was increased with decreasing irrigation frequency from IF2/1to IF1/8, depending on potato growing stage and climatic conditions. Also, wetted area width W and depth D, water losses by deep percolation were increased with decreasing irrigation frequency depending on irrigation water depth d. Soil moisture distribution was effected by irrigation frequency depending on potato growing stage, soil depth and the depth of applied water for each irrigation. Potato root growth was also affected by drip irrigation frequency: the higher the frequency, the lower was the root weight density (RWD). A value of 51-72% of RWD was found in the 0– 10 cm soil layer at all treatments. High frequency irrigation enhanced potato tuber growth, field water use efficiency (FWUE) and crop water use efficiency (CWUE).