## 2 Materials and Methods  
The research site was in Osijek, in the eastern Croatian region of Slavonia (45\({}^{\circ}\)32\({}^{\prime}\) N and 18\({}^{\circ}\)44\({}^{\prime}\) E, altitude 90 m). The climate is a temperate continental climate (Cfwbx climate class), with a mean annual air temperature of 12 \({}^{\circ}\)C and a mean annual precipitation of 650 mm [60]. The soil at the research site is classified as anthropogenic curtic cambsiol (WRB) with a silty clay loamy texture; its main physical and chemical properties are presented in Table 1[61]. Three irrigation rates (a1 = rainfed, a2 = 60-100% of FC, and a3 = 80-100% FC), three N fertilizers rates (b1 = 0 kg N ha\({}^{-1}\), b2 = 100 kg N ha\({}^{-1}\), and b3 = 200 kg N ha\({}^{-1}\)), and four maize hybrids (c1 = OSSK596, c2 = OSSK617, c3 = OSSK602, and c4 = OSSK552) were arranged as split-split plots in a randomized complete block design with three replications. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & & & & & \\ \hline
**Depth** & **Silt** & **Clay** & **(\%)** & **Sand** & **P** & **RC** & **AC** & **PWP** & **PD** \\
**(cm)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(\%)** & **(g cm\({}^{-3}\))** \\ \hline
0–30 & 64.7 & 32.5 & 2.8 & 44.8 & 39.6 & 5.2 & 23.7 & 2.75 \\ \hline \hline \multicolumn{10}{c}{**Chemical Properties**} \\ \hline
**Depth** & **pH** & **Al-P\({}_{2}\)O** & **Al-K\({}_{2}\)O** & **Organic matter** & **CaCO\({}_{3}\)** & **CoCo\({}_{3}\)** \\
**(cm)** & **H\({}_{2}\)O** & **KCI** & **(mg/100 g)** & **(\%)** & **(\%)** & **(\%)** \\ \hline
0–30 & 5.59 & 6.60 & 26.40 & 29.70 & 2.55 & 1.25 \\ \hline \hline \end{tabular} \(\overline{\text{P}}\) = porosity; RC = retention capacity; AC = air capacity; PWP = permanent wilting point; FC = field capacity; SAT = saturation; PD = particle density.  
\end{table} 
Table 1: Physical and chemical properties of the soil at the study site. The sizes of the basic experimental plots were as follows: a = 235 m\({}^{2}\), b = 78.4 m\({}^{2}\), and c = 19.6 m\({}^{2}\), where the total size of the experimental plot was near 1 ha (Figure 1). Each experimental plot had four rows of maize plants added on each side of the plot, which served as protective belts to prevent the study treatments from overlapping. The 3 m wide free space between the plots allowed for the passage of the irrigation system. Maize crop was irrigated with a traveling sprinkler system with a maximum 30 m watering range. Water for the system was pumped from a 37 m deep well that was located near the experimental plot at a 5-7 L s\({}^{-1}\) flow rate using an electric pump (5.5 kW). Water analysis was done according to the Food and Agricultural Organization (FAO) water quality standards for agriculture [62]. As presented in Table 2, there were no chemically derived contaminants, while the Mg\({}^{2+}\) content was slightly higher (5.076 me/L) than the maximum contaminant level (MCL). The sodium adsorption ratio (SAR) was 11 me/L, and the ECw was 0.97 dS/L, which means that water could be used with a slight-to-moderate degree of restriction on use. The irrigation time was determined by measuring the soil water content (SWC) with the use of granular matrix sensors (GMSs). Sensors were placed at two depths (15 and 30 cm) in each irrigation treatment and replicate, which means that a total of 18 sensors were placed in the experimental plot. Before the placement in soil, the GMSs were calibrated to the soil in a trial plot by comparing gravimetric measurements and sensor readings.