Determining Water Management Indicators in Olive Production Poles in the Country
Olive is one of the important products with economic and nutritional value, which nowadays, due to the growing trend of its consumption, has attracted the attention of farmers and officials to increase the cultivated area. Although the issue of the volume of water consumed by the agricultural sector for the production of crops in the country has always been a debatable and controversial issue among experts, until now there has not been a relatively accurate measurement or estimation in the world and the country level regarding the volume of irrigation water for most agricultural products, especially olives. Most of the researches conducted to determine the water requirement of the olive tree have been conducted in experimental plots, and no comprehensive research has been conducted regarding the amount of water given by the operators to the olive orchards, as well as the actual values of the water productivity of the mentioned product. The purpose of this study was to evaluate irrigation management and determine water productivity in olive orchards managed by local farmers in the country.
In this research, considering that the performance of most horticultural crops, particularly olives, is influenced by both age and climatic factors, measurements were conducted over two consecutive years, 2017 and 2018. Following the latest statistical report from the Ministry of Agricultural Jihad, the project's pilot provinces were chosen based on their prominence in olive cultivation and production. These regions, comprising the provinces of Zanjan, Fars, Gilan, Qazvin, Semnan, and Golestan, collectively account for approximately 78% of the area under cultivation and more than 85% of the total olive production in the country. Once the pilot provinces within the country were identified, the selection of pilot cities within each province was based on considerations of both area under cultivation and olive production. The orchards within these pilot cities were chosen strategically to ensure the precise determination of the average irrigation water for olive orchards, with a notable degree of accuracy. The study encompassed a total of 102 olive orchards, comprising 20 orchards employing surface irrigation systems and 82 orchards utilizing drip irrigation systems.
The average volume of irrigation water, yield, irrigation water productivity, and applied water productivity in the selected provinces are significantly different at a probability level of 1%. According to the study, the volume of irrigation water used in olive orchards varied from 2848 to 11463 m3/ha, with a weighted average of 6011 m3/ha. The average yield of olives in the production poles of this product has varied from 1500 to 11000 kg/ha over the two-year period, and its weighted average has been 4867 kg/ha. It is also worth mentioning that the water productivity ranged from 0.2 to 2.40 and its weighted average was 0.95 kg/m3. Furthermore, the applied water productivity in the selected provinces ranged from 0.18 to 1.45 and its weighted average was 0.63 kg/m3. Upon evaluating the efficiency of irrigation in the olive orchards, it was observed that the quantity of water delivered was approximately 27% and 17% less in comparison to the irrigation requirement calculated using recent 10-year meteorological data and NETWAT, respectively. In other word, forced deficit irrigation has taken place in the olive orchards.
Based on the findings of the research, and taking into consideration the average irrigation water and area under cultivation specific to each province, the total annual irrigation water volume required for olive production in the six major olive-producing provinces was estimated. These provinces, which account for more than 85% of the annual olive production in the country, necessitate approximately 340 million cubic meters of water. When extending this calculation to include other olive-producing regions, the national total reaches approximately 457 million cubic meters. In simpler terms, the country annually consumes roughly 0.5 billion cubic meters of water for olive cultivation. The performance of agricultural products, particularly olives, hinges not only on water but also on a Numerous other factors. Diligently addressing each of these factors can significantly enhance yield and increas water productivity. Therefore, by implementing effective irrigation water management, improving agricultural conditions, and optimizing input factors, water productivity and crop production can be increased.