Estimating the economic value of irrigation water based on different approaches to preparing paddy fields data in Guilan province

Rice production is the main activity of agricultural economy in Guilan province. Rice is sensible to water deficit and its occurrence results in yield penalty. The present study estimated the economic value of rice irrigation water in Guilan province to determine the value of this scarce input in this province. To determine the economic value of irrigation water, the production function approach and cross-sectional data of 2014-2015 from 544 paddy fields were analyzed using cluster sampling method in the province. The data used include the amount of different inputs, the amount of yield, the cost of inputs, and the value of yield. Field data were prepared from three approaches including: eliminating outliers and extreme observations (the first approach) based on box plot, use of yield-input equation for selecting data set (the second approach), and selecting field data based on Agricultural-Jihad Organization standard pattern of paddy input-yield levels in different regions of Guilan province (the third approach). The results showed that the average economic values per cubic meter of irrigation water in paddy fields of Guilan province were 15240, 17280, and 17240 Rials, respectively.