Investigating virtual water content and agricultural water productivity indicators in crops (case study: Dehloran county, Ilam province)

Introduction

Due to the limited water resources in the Iran, optimal utilization of water resources is necessary to achieve food security and sustainable development of the agricultural sector. One of the suitable solutions for the optimal use of water resources is to estimate the virtual water content and the physical and economic water productivity of agricultural products. Virtual water is the amount of water that an agricultural product consumes during the production process to reach the stage of evolution, and its amount is equivalent to the total amount of water consumed in the different stages of the production chain from the beginning to the end (Noori et al. 2020). The amount of virtual water required to produce a product is different according to climatic, cultural, management and planning conditions in each country and even region. This issue makes it necessary to study virtual water content estimation in each region (Baghbanyan et al. 2020). In recent years, many types of research have been conducted to estimate the virtual water content and the physical and economic productivity of water in crops (Molareza Qassab et al. 2020; El-Marsafawy and Mohamed, 2021; Tavakoli et al. 2022; Akhavan et al. 2023). Dehloran county is the main pole of agricultural production in Ilam province. So far, no study has been conducted in the field of estimating the virtual water content of crops in Dehloran county. This study was conducted to estimate virtual water content and physical and economic water productivity of crops (wheat, barley, maize, rapeseed, tomato, cucumber, carrot, melon, watermelon and sesame) of Dehloran county.



Materials and Methods

The area studied in this research is Dehloran county, which is located in the south of Ilam province. Dehloran county with 6229 square kilometers constitutes about one-third of the total area of Ilam province (Jaberi et al. 2019). Dehloran county has 103000 hectares of suitable agricultural land, of which 67000 hectares are irrigated and 36000 hectares are rainfed, and it is considered the agricultural pole of Ilam province (Ahmadi, 2020). Most of the irrigated area in Dehloran county is devoted to the cultivation of crops such as wheat, barley, maize, rapeseed, tomato, cucumber, watermelon, melon, sesame and carrot. This study investigated the virtual water content and the physical and economic water productivity of these crops in the agricultural year 2021-2022. The virtual water content of crops was estimated from the sum of green, blue, gray and white virtual water. In this study, the FAO Penman-Monteith and USDA methods were used in CROPWAT 8.0 software to estimate reference crop evapotranspiration and effective rainfall. Crop yields, nitrogen fertilizer consumption rates, production costs and sales prices of crops were obtained from the agricultural jihad of Dehloran county. To check the validity of the mentioned data, an interview was conducted with the farmers of Dehloran county. The results of the interview confirmed the validity of the data. According to the data obtained from the water resources affairs of Dehloran county, the irrigation efficiency is equal to 85%, which was used to estimate the gross irrigation requirement. Crop Per Drop (CPD), Benefit Per Drop (BPD), Net Benefit Per Drop (NBPD) and Unit Virtual Water Value (UWV) indicators were used to estimate the physical and economic water productivity of crops.



Results and Discussion

The results of this study showed that the virtual water content of wheat, barley, rapeseed, maize, watermelon, melon, sesame, tomato, cucumber and carrot crops is equal to 1.82, 1.64, 3.90, 1.49, 0.31, 0.29, 6.99, 0.49, 0.30 and 0.35 m3/kg, respectively. The amount of physical water productivity (CPD index) of wheat, barley, rapeseed, maize, watermelon, melon, sesame, tomato, cucumber and carrot products is equal to 1.53, 2.04, 0.63, 0.81, 4.17, 5.45, 0.22, 2.59, 5.45 and 3.94 kg/m3, respectively. The amount of BPD index of wheat, barley, rapeseed, maize, watermelon, melon, sesame, tomato, cucumber and carrot crops is equal to 0.17, 0.19, 0.14, 0.09, 0.13, 0.16, 0.10, 0.09, 0.19 and 0.12 million rials/m3, respectively. The amount of NBPD index of wheat, barley, rapeseed, maize, watermelon, melon, sesame, tomato, cucumber and carrot crops is equal to 0.06, 0.09, 0.04, 0.06, 0.07, 0.05, 0.10, 0.04, 0.11 and 0.07 million rials/m3, respectively. The amount of UWV index of wheat, barley, rapeseed, maize, watermelon, melon, sesame, tomato, cucumber and carrot crops is equal to 0.06, 0.06, 0.06, 0.08, 0.10, 0.10, 0.06, 0.07, 0.12 and 0.09 rials/m3, respectively. According to the CPD index, cucumber, melon, watermelon, carrot and tomato crops are placed in the first to fourth priorities for cultivation in Dehloran county. According to the BPD index, cucumber, barley, wheat, melon and rapeseed crops are placed in the first to fourth priorities for cultivation in Dehloran county. According to the NBPD index, cucumber, sesame, barley, watermelon and carrot crops are placed in the first to fourth priorities for cultivation in Dehloran county. According to the UWV index, cucumber, melon, watermelon, carrot and maize crops are placed in the first to fourth priorities for cultivation in Dehloran county.