## 3 Results  
### Weather Conditions, Groundwater Levels, and Soil Water Contents  
The first year of the field study was extremely wet and warm (Figure 2). The amount of rainfall during the maize growing period was higher by 68.4% than the LTA (368 mm). During the period of maize vegetative growth, due to the excessive amount of precipitation that fell in a very short time in the area of Osijek, a natural disaster with a large amount of precipitation on 28 May and a natural disaster with a large amount of precipitation and flood on 9 June were declared by local authorities. As for air temperatures, during the growing period, the air temperatures were 0.2 \({}^{\circ}\)C higher than LTA (18.1 \({}^{\circ}\)C).  
The second year of the field study was very warm and extremely dry. The amount of rainfall during the growing period was 33.4% lower than the LTA and the air temperatures were 1.82 \({}^{\circ}\)C higher than LTA. The last year of the field study was extremely warm and average in terms of the rainfall amount. The amount of rainfall was 21% lower than the LTA, while the air temperatures were 2.4 \({}^{\circ}\)C higher than the LTA.  
Due to large differences in the rainfall during the study period, considerable changes in groundwater level were also recorded (Figure 3). In an extremely rainy year, the groundwater level was in the range of 20 to 160 cm from the soil top. In such a soil condition, anaerobic processes (anoxia) occurred in the soil, and yield reduction and increased nutrient leaching were expected. In an extremely dry year, the groundwater level ranged from 180 to 400 cm.  
During the last year of the field study, the groundwater level ranged from 290 to 430 cm, where it can be claimed that the water level did not affect plant growth or yield formation.  
Figure 3: Groundwater levels (cm) during the study period.  
Figure 2: Rainfall (mm) and air temperatures (\({}^{\circ}\)C) during the study period and the long-term average (LTA, 1981–2010).  
During the first year of the study (extremely wet), the averages for the irrigation treatments' SWC were 48.14 cbar for a1, 31.25 cbar for a2, and 24.36 cbar for a3 (Figure 4), which, according to the calibration results, means that the SWC was in the range of 80 to 100% FC for most of the growing period. For this reason, the maize in the a2 irrigation treatment was irrigated only once (20 July), while in a3, the maize was irrigated three times (6 and 20 July, 13 August). Accordingly, the net irrigation during the first year of the study was 35 mm (a2) and 105 mm (a3). During the second year of the study, the SWC ranged from 28 cbar (a3) to 148 cbar (a1). Since the growing season was extremely dry, a considerably higher amount of irrigation water was added compared to the previous year to keep the SWC at the set levels. Accordingly, the net irrigation for an extremely dry year was 105 mm (a2) and 245 mm (a3). Although in the last year of the study, there was no considerable aberration from the LTA in terms of the rainfall amount, the high air temperatures (Figure 2) and very low groundwater levels (Figure 3) resulted in a low SWC. For this reason, the net irrigation in the last year of the study was 175 mm (a2) and 245 mm (a3).