طراحي ، ساخت و نصب لايسيمتر وزني به منظور تعيين نياز آبي گياهان زراعي

Design, construction and installation of weighing lysimeters for determining consumptive use of agricultural crops

Knowledge of crop evapotranspiration, the combined process of evaporation and plant transpiration, is important in agriculture for scheduling farm operations and designing and managing irrigation and drainage systems. Weighing lysimeters are the most practical research method for direct measurement of short-term evapotranspiration. The main objective of this research was design, construction, and installation of two weighing lysimeters at Agricultural Research Station of Tehran University located at Karaj in order to determine the consumptive use of agricultural crops and reference crop. The lysimeter used for agricultural crops has a surface area of 9m2 with soil depth of about 2m. The one used for reference crop (grass) has a surface area of 16 mz with soil depth of 1 m. Each lysimeter rests on a sensitive scale capable of measuring to the nearest 1000 gr. The weighing system is electronic with four load cells were used in each lysimeter for weighing operation. The weighing system accuracy is 0.1 and 0.06 mm of water depth for the first and second lysimeter, the soil tank was steel-made and reinforced against imposed forces and filled with disturbed soil. Lysimeters have been installed in the direction of the prevailing wind and 400 meter far from the farm edge. These lysimeters have free-drainage system. In this study, all limitations regarding to design and execution of lysimeters were taken into account.