Investigation of irrigation water volume and water productivity of walnut orchards in Fars province

Although walnut is one of the most important products in the world and in Iran, but so far little research has been done on irrigation and especially its water productivity. In this study, the yield, volume of applied irrigation water and irrigation water productivity of walnut orchards in three major regions producing this product in Fars province and in drip and surface irrigation systems were measured and studied. Net and gross water requirements of walnuts from the national document Water requirement, Penman Montieth method in the year of research and for long-term, estimated and compared with the amount of water applied in orchards by t-test. The results for a total of three areas and regardless of the type of irrigation system showed that the applied water was less than the gross water requirement of about 1500 cubic meters per hectare and this difference was not statistically significant. But compared to the long-term gross water requirement, this difference was about 3,000 cubic meters per hectare, which was significant. The amount of water applied in walnut orchards under drip irrigation systems was about 1600 cubic meters per hectare less than surface irrigation systems. However, comparing the amount of applied water with the gross water requirement of orchards showed that in drip irrigation systems, 1800 cubic meters per hectare was more than needed and in surface irrigation systems, 3600 cubic meters per hectare was less than required. In general, no significant difference was observed between yield values, applied water volume and water productivity in drip and surface irrigation systems. But in the study areas, yield values, water productivity and applied water volume were different.