Uniformity of Water and Nitrate Distribution under Furrow Irrigation Through Surge Flow

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 uniformities of the water and nitrate are the most important indicators of the surface irrigation fertigation. For this purpose in this research, water and nitrate distribution uniformity indicators in furrow fertigation with surge and continuous flow regimes 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 advancing cycles, wetting phase and last advancing cycle plus start of wetting phase. Fertilizer injection for continuous flow was applied in the second half of advancing and wetting phases. Low quarter distribution uniformity of the 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 the 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 values 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 the water and nitrate application efficiency and distribution uniformity. The values of these indices for nitrate in experiments with surge and continuous flow regimes were calculated to be 45.0-80.5% and 68.2-79.5%, respectively. Overall, fertilizer injections in all surges and second half of advancing phase, respectively in furrow fertigation with surge and continuous flow regimes stand at the proper management practices for water and fertilizer.