Estimation of the Optimal Use of Irrigation Water in Production of Lettuce – An Economical Approach

Abstract

The lack of data, information and studies examining the economic issues which related to crop water consumption are the main obstacles facing decision makers, legislators and farmers to optimize the use of water for agricultural purposes. This study aims to determine the optimal quantity of irrigation water for lettuce (lactuca sativa L.), which is a crop that does not have local data on its behavior of water consumption. To achieve the goals of the study, field experiment was conducted under trickle irrigation condition at the Tripoli Center of Agricultural Research during winter season of 2017.Four levels of irrigation water 130 mm, 195 mm, 260 mm and 320 mm were applied. These levels were selected based on the water requirements as calculated from Penman- Monthieth -FAO 1998 equation to represent 50, 75, 100, and 125% of total irrigation water required by lettuce crop, respectively. A second degree polynomial equation was fitted (R 2 = 0.64) for production function (yield in ton/ha versus. applied irrigation water in m3/ha). The results revealed that the increase in the quantity of irrigation water led to a higher yield of lettuce to a specific point and then the production rates decreased. According to the water price, the results of economical analysis indicated that the optimal quantity of irrigation water estimated of the lettuce which achieved the optimal productivity was found at 2506 m3 / ha. Many studies and researches on several crops must be conducted under field conditions in order to reach the optimal approach that ensures achieving high yield production through optimal use of limited water resources