Abstract

Abstract Determination of fertigation criteria in new surface irrigation methods, especially furrow irrigation through surge flow, is necessary in order to increase water and fertigation use efficiency. Distribution uniformity of water and nitrate is the most important indicator of surface irrigation fertigation. For this purpose in this research, water and nitrate distribution uniformity indicators in furrow fertigation with surge and continuous flow were evaluated using field experiments. The study was conducted in a soil with clay loam texture at the experimental station of the College of Agriculture and Natural Resources, University of Tehran in June, 2012. Fertigation management strategies in experiments with surge flow included injecting fertilizer during all advance cycles, wetting phase and last advance cycle plus start of wetting phase. Fertilizer injection for continuous flow was applied in second half of advance and wetting phases. Low quarter distribution uniformity of nitrate in experiments with surge and continuous flow amounted to 54.4-93.8% and 77.7-93.6%, respectively. Also, low quarter distribution uniformity of water for the same experiments amounted to 88.0-93.7% and 78.0-90.5%, respectively. Nitrate losses in all experiments were through runoff and its value in these experiments amounted to 5.1-47.1% and 3.7-27.2%, respectively. Low quarter concept was also used as an index for evaluating water and nitrate application efficiency and distribution uniformity. The values of this index for nitrate in experiments with surge and continuous flow was calculated to be 45.0-80.5% and 68.2-79.5%, respectively. Overall, fertilizer injection in all surges and second half of advance phase, respectively in furrow fertigation with surge and continuous flow stands proper management practices for water and fertilizer in agricultural fields. Keywords: Surge Irrigation, Nitrate Losses, Fertigation Management, Water Distribution Uniformity, Efficiency