Optimisation of irrigation system in arid land pistachio orchards

Abstract

This research was designed to evaluate and compare the applicability of two different types of irrigation including traditionally (surface irrigation) and simple sub-surface drip irrigation (using pricked-pipe covered with plastic cloth). Two plots containing 39 pistachio trees with 720 m2 area were selected in Rafsanjan, Iran. Both plots were irrigated using exactly the same quantity and quality of water for 2 years. At the end of the second year the yield was harvested separately and compared. The weight of fresh and dried crops in sub-surface irrigation plot to those of surface irrigation plot were 1.895 and 2 respectively. Annual shoot growth of tree was measured in two plats. The value of Plot Growth Index (PGI) in surface irrigation plot and sub-surface irrigation plot calculated 2237.5cm and 4580.5cm respectively. In addition, the dried weight of weeds in surface irrigation plot was 82kg while it was only 21 kg in sub-surface irrigation plot. Results show the considerable difference in two irrigation systems efficiences and relatively higher preference of sub-surface system than traditionally surface method.Finally, due to sever shortage of agricultural water in the studied area, it has been advised to optimize traditionally used irrigation systems toward new methods with minimum water loss such as evaluated subsurface method.