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| Effect of solution concentration onfertigation uniformity of impact sprinkler |
| TU Qin1*, YI Meng2, LI Hong2, ZHANG Kai2, ZHANG Qiankun2 |
| 1. School of Intelligent Equipment, Changzhou College of Information Technology, Changzhou, Jiangsu 213164, China; 2. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract Field experiments on the impact sprinkler 10PY2H were conducted to evaluate effect of solution concentration on fertigation uniformity of the sprinkler irrigation system by simultaneously measuring the radial distributions of fertilizer solution, solution concentration and fertilizer applied. The potassium chloride(mother liquor)with the concentrations of 0, 20, 35, 50, 65, 80 g/L was used in the experiments. The superposition method was then employed to derive the Christiansen uniformity coefficient CU, distribution uniformity DU and statistical uniformity Us of three indicators after overlapped fertigation. The results reveal that the effect of solution concentration of mother liquor on both the irrigation uniformity and the fertigation uniformity of the impact sprinkler is generally nonlinear. An increase in solution concentration of mother liquor has a relatively low impact on the uniformity of fertilizer solution and solution concentration, but a significant influence on the uniformity of fertilizer applied. Overlapped fertigation intensifies the numerical difference in the indicators between different measuring points. The radial distribution of fertilizer applied shows the greatest change as the solution concentration increases. When the solution concentration of mother liquor reaches 80 g/L, the fertilizer applied mainly gathers around 20% to 60% of sprinkler range, resulting in a sharp decrease in the fertigation uniformity. In most of the cases involved, the solution concentration at 90% to 100% of sprinkler range is relatively higher when the solution concentration of mother liquor is lower than 35 g/L, which is contrary to the conclusion that the concentration decreased along the pipeline in drip fertigation obtained previously. Among the three indicators of uniformity, the CU value is the highest, and the DU is gene-rally the lowest with the greatest change across different conditions, especially for the fertilizer applied. Thus, DU can reflect the shortage of fertilizer in the low-value area at different solution concentrations. The fertilizer contours indicate that the spatial distributions of fertilizer solution and fertilizer applied are similar while the distribution of solution concentration is contrary to both of them. This may be related to the higher concentration of solution at the farther end of sprinkler range shown in the impact sprinkler.
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Received: 21 August 2019
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