Irrigation is a required management practice in pistachio nut production for higher quality and quantity. A proper irrigation management technique that maintains an optimum soil moisture and environment in the root zone increases yield of the pistachio nut tree. Since pistachio tree on the Pistacia vera rootstock does not tolerate excess water in the root zone, over-irrigation must be avoided. In the determination of water requirement of pistachio tree, pan evaporation is commonly used due to its simplicity.
