## 3 Results
### Impact of Irrigation (a), N Fertilizer Rate (b), and Maize Hybrid (c) on Yield and Grain Compounds
Figure 7: Relationship between irrigation (a1 = rainfed, a2 = 60–100% field capacity (FC), and a3 = 80–100% FC) and the tested variables—(**a**) yield, (**b**) protein, (**c**) starch, and (**d**) oil content—and N fertilizer rate (b1 = 0 kg N ha\({}^{-1}\), b2 = 100 kg N ha\({}^{-1}\)) and the tested variables—(**e**) yield, (**f**) protein, (**g**) starch, and (**h**) oil content—in different weather conditions (extremely wet, extremely dry, and average year) significantly different at \(p<0.05\) (*) and \(p<0.01\) (**). The efficiency of the irrigation and N fertilizer rate are presented in Table 5. In the extremely wet growing season, the IWUE was lower when the irrigation rate was higher. This was opposite to the extremely dry year, where the highest IWUE was found for the fully irrigated treatment (a3). In the average growing season, the highest IWUE was found for the a2 irrigated plots. If the IWUE was analyzed in relation to the N fertilizer rate, then the efficiency was weather and N fertilizer rate dependent, and it ranged from \(-12.57\) kg ha\({}^{-1}\) m\({}^{-1}\) (a2b2, extremely wet) to 18.19 kg ha\({}^{-1}\) m\({}^{-1}\) (a2b3, extremely dry). As for the FUE, in the extremely wet growing season, the highest FUE was found with the maximum N fertilizer rate (b3), while in the other two growing seasons, the highest FUE was found for the N fertilizer rate, regardless of the weather conditions. If the FUE was analyzed in terms of the irrigation rates, then the FUE ranged from 5.95 (a2b3, average year) to 38.3 kg ha\({}^{-1}\) (a3b2, extremely dry). Soil Nitrate Level across Weather Conditions, Irrigation Levels (a), N Fertilizer Rates (b), and Soil Sampling Times (c)  
The soil nitrate levels showed a typical decrease during the study period, with the highest values at the beginning of the study and decreasing levels toward the end of the study period (Figure 9). The same pattern was present in each of the study years, depending on the sampling time, i.e., the highest values were measured in the first sampling, which was before sowing, while the soil N values were reduced after the harvest. These differences were more pronounced in the extremely wet and extremely dry years. Figure 8 shows that the maximum soil N (%) level during the extremely wet year (0.17%) was in the rainfed  
Figure 8: Relationship between (**a**) protein and oil (%), (**b**) starch and oil (%), and (**c**) protein and starch content (%) in different weather conditions (extremely wet, extremely dry, and average) significantly different at \(p<0.05\) (*) and \(p<0.01\) (**). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Growing Season**} & **Extremely** & **Extremely** & **Average** & & **Extremely** & **Extremely** & **Average** \\  & **Wet** & **Dry** & & & **Wet** & **Dry** & **Average** \\ \hline \multicolumn{8}{c}{IWUE (kg ha\({}^{-1}\) mm\({}^{-1}\))} & \multicolumn{8}{c}{FUE (kg ha\({}^{-1}\) kg\({}^{-1}\))} \\ a2 & \(-3.51\) & 9.53 & 12.90 & b2 & 28.50 & 31.90 & 9.30 \\ a3 & \(-6.19\) & 11.87 & 7.68 & b3 & 30.60 & 20.75 & 7.20 \\ \multicolumn{8}{c}{a2} & \multicolumn{8}{c}{b2} \\ b1 & 2.57 & 9.05 & 11.60 & a1 & 33.20 & 27.30 & 11.70 \\ b2 & \(-12.57\) & 11.43 & 8.57 & a2 & 27.90 & 29.80 & 6.40 \\ b3 & \(-10.57\) & 18.19 & 8.40 & a3 & 24.30 & 38.30 & 9.70 \\ \multicolumn{8}{c}{a3} & \multicolumn{8}{c}{b3} \\ b1 & 0.38 & 4.69 & 12.61 & a1 & 30.80 & 17.20 & 8.75 \\ b2 & \(-8.10\) & 9.18 & 11.80 & a2 & 32.20 & 22.00 & 5.95 \\ b3 & \(-7.24\) & 9.31 & 11.18 & a3 & 26.80 & 22.85 & 7.00 \\ \hline \hline \end{tabular}  
* IWUE = irrigation water use efficiency (kg ha\({}^{-1}\) mm\({}^{-1}\)); FUE = fertilizer use efficiency (kg ha\({}^{-1}\) kg\({}^{-1}\)); a1 = rainfed; a2 = 60–100% field capacity (FC); a3 = 80–100% FC; b1 = 0 kg N ha\({}^{-1}\); b2 = 100 kg N ha\({}^{-1}\); b3 = 200 kg N ha\({}^{-1}\).  
\end{table} 
Table 5: Irrigation water use efficiency (IWUE) and fertilizer use efficiency (FUE) in different weather conditions, irrigation levels, and N fertilizer rates.