optimization of furrow fertigation from environmental

abstract optimal management of water and nutrient could consider as effective on farm method to reduce pollution because agriculture is none point pollution. in this research, an optimal model was presented to reduce nitrate loss in furrow fertigation. the optimal model contains four simulation models for predicting runoff, deep percolation, nitrate concentration in runoff and nitrate concentration in deep percolation. genetic algorithm was used for model solution. decided values were inlet discharge, cutoff time of irrigation, starting time and duration of fertigation. simulation model’s ability to simulate fertigation event cause a comprehensive optimal model of fertigation in different climate, plant, irrigation and fertigation situations. field experiment of furrow irrigation under continues regime was used to evaluate optimal model. optimal decided values for inlet discharge, cutoff time of irrigation, starting time and duration of fertigation was determined 0.184 l/s, 595.2 min, 7.5 min and 162.9 min in plant conditions. these values were 0.21 l/s, 537.1 min, 6.5 min and 143 min in none plant condition. optimal decided values cause 113.86 and 118.3 mg/l mean nitrate loss from farm as runoff and deep percolation under plant and none plant conditions, respectively. optimal model was increased nitrate concentration in deep percolation or decreased nitrate concentration in runoff by increasing inlet discharge because plant increase nitrate concentration in deep percolation. results show plant has effect on optimization then it is appropriate to determine optimal decided values under plant and none plant conditions.