Effect of longitudinal furrow slope on nitrate distribution in surface fertigation

Non-uniform distribution which occurs during manual fertilizing is one of the biggest problems of surface irrigation. This issue needs more research in the field of surface fertigation. The aim of this study is to evaluate the roles of slope and fertigation timing in furrow irrigation. Urea fertilizer was used and nitrate was selected to be the reagent ingredient in order to study the distribution of fertilizer. The research was conducted in agricultural research field of Shahrekord University. A completely randomized block design was employed with four treatments and three replications. The treatments were Control treatment (natural slope, fulltime fertigation) and three periods of fertigation that were first half, second half and fulltime fertigation. Slope changes, fertigation duration, soil depth of the sampling and distance from the furrow beginnings effects were studied on nitrate distribution in the soil. The LSD test was used for statistical analysis. The results demonstrated that slope had a very significant effect on nitrate distribution and storage in the soil (P<0.01). Also, Changes in fertigation timing and duration caused variation in nitrate distribution and the second half fertigation treatment had the highest nitrate distribution uniformity and absorption of 1653.53 mg/kg. Studying simultaneous effects of fertigation timing, soil depth and distance form beginnings of the furrows exhibited that they had no significant impact on each other. Finally, slope and fertigation timing were reported to be the effective factors in the nitrate storage and distribution.