施肥浓度对摇臂式喷头喷灌施肥均匀性的影响

为了研究施肥浓度对喷灌施肥均匀性的影响规律,选用摇臂式喷头10PY₂H,测量其喷灌施肥时肥液体积、施肥浓度、施肥量3种参数的径向分布.试验中,氯化钾溶液质量浓度(即母液浓度)分别为0,20,35,50,65,80 g/L.采用叠加法计算组合喷洒时3种施肥参数的均匀度CU、分布均匀度DU和统计均匀度U_s.分析表明施肥浓度对摇臂式喷头的灌水施肥影响呈现非线性特点.增加母液浓度对肥液体积分布和施肥浓度分布均匀性的影响相对较小,但对施肥量分布均匀性的影响十分显著.组合喷灌加剧了不同测点的数值差异.随着母液浓度增大,施肥量径向分布变化增大,当母液质量浓度增大到80 g/L时,施肥量主要集中在20%~60%射程处,导致施肥均匀性急剧下降;当母液质量浓度小于等于35 g/L时,远端90%~100%射程处的施肥浓度相对更高,与前人得出的滴灌施肥系统施肥浓度沿管道方向递减的规律相反.3个评价指标中,均匀度CU数值最高,分布均匀度DU总体数值最低、变化最大,且以DU变化最为明显,这说明了DU能反映低值区的施肥情况.喷灌施肥等值线图表明肥液与施肥量的分布规律相似,但施肥浓度的分布情况则相反,这可能与射程远端施肥浓度更大有关.

Effect of solution concentration onfertigation uniformity of impact sprinkler

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 U_s 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.