Investigating water footprints and water consumption efficiency of crops of potatoes, sugar beets, tomatoes and forage corn in different climates of Iran

One of the practical strategies for managing water resources is to estimate the plant's water needs and determine the amount of water used in the various stages of crop production. In order to calculate the amount of water consumed by agricultural products in the growth stages, the virtual water index and water footprint are used. Water footprint in a product is defined as the volume of fresh water used in it's production. Water footprint is defined as an indicator for the allocation of fresh water resources that provides valuable insights into the environmental impact of producing a product. Water footprint index shows actual consumption of water in three components: blue, green and gray, which is now considered in the direction of modern management of water resources with an integrated approach. In order to properly assess water consumption in the agricultural sector, it is necessary to study the water footprint index in different climates.

To conduct the research, meteorological data were first obtained from the Meteorological Organization.Then the water needs of sugar beet, potato, forage corn and tomato plants in Hamedan, Ahvaz, Shahrekord, Mashhad and Isfahan climates were calculated from the CropWat software. The yield of the crop and the amount of nitrogen fertilizer used were obtained from the agricultural jihad of each province. crop yield and the parameters required in the calculations were calculated and aggregated through agricultural statistics Then, the average volume of water consumption, virtual water, water footprint and water use efficiency of these products were calculated for the statistical period of 2011-2017. Chapagin et al. (2006) Method was used to calculate water footprint.

In the present study, water consumption for agricultural products was investigated. The results showed that among the studied products, the potato plant with 2945.4 m3/ton in Ahvaz city with hot and humid climate has the highest water footprint and sugar beet with 906.1 m3/ton in climate cold and dry of Mashhad has the least water footprint. The highest amount of virtual water used for the studied plants is potato (0.84 m3/kg), tomato (0.51 m3/kg), sugar beet (0.46 m3/kg) and forage corn (0.39 m3/kg) was respectively to the climate of Ahwaz, Shahrekord, Ahwaz and Isfahan. The lowest amount of water consumption efficiency (1.2 kg/m3) also belonged to the potato in Ahvaz climate. The lowest virtual water and the highest water consumption efficiency for the studied plants were obtained in Hamedan climate.

In the present study, water consumption for agricultural products was investigated. The results showed that the volume of water consumed in the studied products varies in different climates. According to the obtained results, it can be said that the climate of Hamedan due to the low amount of virtual water (0.29, 0.3, 0.19 and 0.14 m3/ kg) and high water consumption efficiency ( 3.43, 3.3, 5.19 and 7.46 kg/m3) for potatoes, tomatoes, sugar beets and fodder corn, respectively, compared to other climates studied for cultivation of all four the product is more suitable. Hence, according to recent droughs and water shortage, available water resources should be used accurately and decision must be made for cultivating the products with less water requirement and better performance.