The Role of Modern Irrigation Systems on Tomato Applied Irrigation Water Management in Iran

Development of modern irrigation systems has been one of the main programs in developing agricultural sector in the past few decades. Assessing the role of these systems in increasing indicators of irrigation water management can play an important role in future national policies and planning. Therefore, this study was conducted with the aim of appraising water consumption management indicators in tomato production in different regions of Iran and evaluating the role of surface drip irrigation systems in increasing these indicators.

In this study, a field survey was conducted to measure yield and applied irrigation water of tomato under the farmers’ management in tomato production hubs. Volume of applied water by farmers in 176 farms in Fars, South Kerman, Hormozgan, Bushehr, Khorasan Razavi, Qazvin, Khuzestan, Golestan, Zanjan, Hamedan and Semnan provinces with different conditions of climates, irrigation methods (furrows and drip), salinity of irrigation water and soil; and different tomato cultivars were measured during growing season 2018-2019. The measured applied irrigation water values were compared with the net irrigation requirements estimated by the FAO Penman-Monteith method using meteorological data from the last 10 years, as well as the values of the national water document. Then, the effect of modern irrigation methods (surface drip irrigation) on applied water, application efficiency and physical water productivity was investigated in the study areas. Crop yield was recorded at the end of the growing season and water productivity (WP) was calcucated as the ratio of yield to total applied water (irrigation water and effective rainfall). Analysis of variance was used to investigate the possible difference between yield, applied water and WP among the hubs. Data adequacy was assessed by using the method provided by Sarmad et al. (2001).

The results showed that yield, applied irrigation water and WP in tomato production hubs were significantly different at the P ≤ 0.01. The average volume of applied irrigation water by the farmers was 7729 m3/ha. Water productivity in production areas varied from 4.33 to 9.52 kg/m3 and its average was 7.10 kg/m3. The average net irrigation requirement and irrigation application efficiency were 674 mm and 78%, respectively. Irrigation application efficiency obtained from the studied tomato farms was slightly higher than the average irrigation efficiency in Iran reported by Abbasi et al. (2016). Deficit irrigation was occurred in the fields of some areas such as Bushehr, Golestan and Semnan. Tomato planting time (spring or autumn) affected applied irrigation water, yield and WP. The volume of water used in autumn planted farms (5356 m3/ha) was less than spring planted farms (9831 m3/ha). The average yield of tomatoes in spring planted farms (74.3 t/ha) was significantly higher than the yield of fields planted in autumn (46.1 t/ha). However, the average of WP in spring planting farms (7.7 kg/m3) was higher than the productivity of farms planted in autumn (6.6 kg/m3). The application of surface drip irrigation systems in comparison with furrow irrigation resulted in 25% reducing in applied water, 10% increasing the application efficiency and 16% improving in water productivity.

In general, the results of this study provide useful information on applied irrigation water management indicators in tomato production to managers and water decision makers within Iran. Proper development and management of drip irrigation systems for row crops such as tomatoes and autumn planting of tomatoes in warm tomato production hubs is recommended for effective use of autumn rainfall. Also, training and application of methods to improve the performance of surface irrigation (using methods to reduce evaporation and the use of low pressure systems) is recommended to increase irrigation efficiency and reduce applied irrigation water.