Simulation of furrow irrigation performance using seasonal modeling under various on-farm water managements

Increasing irrigation efficiency has been become one of the main solutions to be considered on-farm increasing water productivity due to limited water resources. The objective of this study was to apply a seasonal simulation model to determine irrigation performance indicators for different scenarios such as deficit irrigation, inflow rate and frequency of irrigation, under two different fields in Karaj (College of Agriculture and Natural Resources and Seed and Plant Improvement Institute farms) in order to decrease irrigation losses and improve irrigation water uniformity. The results showed that the College farm had more runoff losses due to heavier soil texture and shorter furrows compared with to the Institute farm. Irrigation efficiency increased when reducing inflow rate and frequency of irrigation, irrigation efficiency increased about 40% in the higher irrigation frequency by reducing inflow rate from 0.64 to 0.22 L/s. In addition, the highest efficiency happened in three-day irrigation frequency with 0.22 L/s inflow rate. However, the Institute farm had larger deep percolation losses than the college farm. Moreover, the results of simulated soil moisture during the growing season showed that the difference between the minimum and maximum soil moisture was less under lower values of inflow rate and irrigation frequency (such as three-day irrigation frequency and 0.3 L/s inflow rate in the Institute farm and three-day irrigation frequency and 0.22 L/s in the College farm). The seasonal simulation model had good capability to evaluate furrow irrigation performance under different on-farm water managements.