## 3 Results and Discussion
### Distribution Uniformity
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & & \\  & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** \\ \hline pa & HHCU, \% & 93.6 & 86.9 & 89.4 & 88.9 & 83.0 & 93.4 & 91.5 & 85.2 & 83.3 & 88.7 & 86.1 \\ \hline
70 & & 96.8 & 91.5 & 93.1 & 92.8 & 89.0 & 95.7 & 94.5 & 90.4 & 89.2 & 92.6 & 91.0 \\
75 & & 94.1 & 89.1 & 91.2 & 90.7 & 85.9 & 94.5 & 92.9 & 87.7 & 86.1 & 90.6 & 88.5 \\
80 & DUpa (\%) & 93.4 & 86.3 & 88.9 & 88.3 & 82.2 & 93.1 & 91.1 & 84.5 & 82.5 & 88.1 & 85.5 \\
85 & & 92.5 & 82.8 & 86.0 & 85.4 & 77.7 & 91.3 & 88.8 & 80.6 & 78.1 & 85.1 & 81.8 \\
90 & & 91.5 & 78.5 & 82.5 & 81.7 & 72.2 & 89.1 & 86.0 & 75.7 & 72.6 & 81.4 & 77.2 \\ \hline  & & & & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 4: Mean HHCU and DUpa of the four Ids used in the control condition. Figure 6: Distribution uniformity (DUpa) of the different segments with sprinklers at 1.6 m above the ground and pa of 80% for: **(a)** control condition; **(b)** corn at V\({}_{4}\) (1.2 m in height); **(c)** corn at V\({}_{6}\) (1.4 m in height); **(d)** corn at V\({}_{10}\) (1.55 m in height); **(e)** corn at reproductive stage (R\({}_{1}\)BC, mean height of 2.8 m) with sprinklers below the canopy (1.60 m) and **(f)** corn at R\({}_{1}\)AC, but with sprinklers elevated above the canopy (3.2 m). Black solid line: 15% (40 mm); solid grey line: 25% (24 mm); dashed grey line: 50% (12 mm) and dashed black line 100% (6 mm). When the crop reached a height of 1.20 m (V4, Figure 6b), interference of the applied water started, which was evidenced in a decrease of DUpa of 0.5% to 10.8% with respect to the control, considering all the Ids applied and all the segments. When the crop was 1.40 m in height (V6), DUpa continued to decrease (between 6.9% and 12% for all the Ids and segments) up to values between 60% and 70% for segments 4 and 6 using an Id of 6 and 12 mm, respectively (Figure 6c). Similar uniformity (55%) was obtained in a 0.5 m tall corn crop irrigated with a center pivot [33]. When sprinklers were below the canopy (V10, 1.55 m), the decrease in DUpa with respect to the control increased, reaching between 20% and 40% for segments 1, 2, 3, 5 and 7 (Figure 6d). In turn, at the same stage, the lowest DUpa was obtained with the lowest Id applied (100%), with variability between segments being also very high. When the crop was 2.80 m in height (R1), DUpa was obtained under two operating conditions: sprinklers at 1.60 m (R1 BC, below the canopy) and 3.2 m above the ground (R1 AC, above the canopy). Mean DUpa decreased between 52.5% and 67% with respect to the control with the sprinklers below the canopy (Figure 6e), the highest decrease of all the tests, whereas the elevation of sprinklers improved DUpa, with a reduction of 34.6% to 47% with respect to the control (Figure 6f). These results differ from those reported by [34], who evaluated LDN (low drift nozzle-Senninger) sprinklers at different positions and concluded that the highest position increased the drift loss of the sprinkled droplets. These contrasting results were due to wind speeds: 3 m s\({}^{-1}\) in the present work and 10 m s\({}^{-1}\) in the work of [34]. However, no differences in uniformity were found in a study evaluating impact sprinklers above and below the canopy in alfalfa [35]; this result is explained by the planophile orientation and trifoliate compound leaves of alfalfa, unlike corn leaves, which are linear to linear-lancecolate simple leaves. To evaluate the influence of sprinkler spacing on uniformity, the mean spacing of each segment vs. mean DUpa was represented for all the Ids of the control, vegetative stages (V4, V6 and V10) and reproductive stages with sprinklers below the canopy (R1 BC) and above the canopy (R1 AC) (Figure 7). While DUpa decreased at the vegetative stage and at R1 AC, this result was not due to spacing but to canopy interference since the reduction was similar for all spacings.