Investigating the Volume of Applied Water and Agricultural Water Productivity in Olive Production in Qazvin Province

Despite the importance of determining indicators of water consumption management in the agricultural sector for use in national macro-planning, so far, indicators of water consumption management in the production of agricultural and horticultural crops have received less attention. This matter is of double importance regarding the programs to improve the efficiency of water consumption. In this regard, the determination of the volume of applied water, as one of the important and influential indicators in agricultural planning, should be considered. Therefore, conducting a research that can lead to more accurate information about the amount of water used for various agricultural and horticultural crops in the country is necessary and necessary, and its results can be of great help to the decision-making of officials related to water and agriculture.

Qazvin province is one of the poles of olive production in the country, and the most important olive growing areas of the province are located in Tarem region, between Gilan and Zanjan provinces. The cultivated area of olive orchards in the province in 2017 was 9,300 hectares, and the area of fertile olive orchards was about 6,500 hectares. Also, the average yield of olives in the province is estimated at 2977 kg/hectare. This research was conducted with the aim of directly measuring the water consumption of olives in the olive production pole of Qazvin province (Taram region). Olive is the main product of gardeners in most villages of this region and is the only source of income for many villagers. So that more than 90% of gardeners' economy depends on the production of olives, and olives are their main product in 45 villages out of 105 villages in the region. In this regard, due to the severe limitation of water resources in the region and the development of new olive orchards, it is necessary to pay attention to the amount of water consumed by the orchards and plan based on the monitoring of the current state of water resources exploitation. In this research, measuring the amount of olive water consumed by considering various factors such as; Irrigation method, size of garden plots, soil texture, quality of water and soil resources, planting intervals and the level of education of the users were done. For this purpose, selected gardens for measuring water consumption were chosen in such a way as to cover the diversity of these factors. The volume of water given was measured with WSC flume (depending on the flow rate from type 3 to 5) or ultrasonic flow meter without interfering in the farmers' irrigation program. In the current research, in order to monitor the flow rate of the pumping station in pressurized irrigation systems, an ultrasonic flow meter device model PERCISION FLOW190PD was used and after the hydraulic test and calibration, the flow rate of the pumping station was measured in the selected gardens. After determining the amount of water entering the garden by carefully monitoring the garden irrigation schedule (watering time, irrigation cycle, number of irrigation times during the growth period), the amount of water consumed by the olive crop was measured for each of the selected gardens. Also, effective rainfall was estimated by SCS method.

The results showed that the range of irrigation water depth changes was between 5 and 30 mm with an average of 18 mm and a standard deviation of 17.7 mm. The minimum and maximum number of irrigations were 18 and 90 with an average of 39 and a standard deviation of 19.91. The average volume of applied water in the studied olive orchards in Tarem region was 6006 m3/ha with a standard deviation of 1517 m3/ha in all types of irrigation methods. The average yield of olives in the studied orchards in 2018 was equal to 5.46 tons/ha with a standard deviation of 4.8 tons/ha, which was higher than the average yield of the province (3 tons/ha). According to the amount of water consumed and the yield, the average irrigation water efficiency in the studied orchards is 1.13 kg/m3 and the irrigation water efficiency and effective rainfall is equal to 0.78 kg/m3. In this regard, the highest index of agricultural water productivity index was recorded in dense olive groves of the region with the amount of 3.58 kg/m3. The most important reasons for the high agricultural water productivity index can be mentioned such as appropriate plant nutrition, proper fertilization of the land and soil texture modification, observance of horticulture principles, low-problem irrigation system, regular and correct irrigation cycle, and trained workers.