## 4 Discussion  
The impact of irrigation on the GY depended on the weather conditions, i.e., in an extremely wet year, the maize GY from the a3 irrigation treatment was significantly (\(p<0.01\)) lower compared to those from the rainfed (a1) and a2 irrigation treatments (Figures 6 and 7), which was the complete opposite of the remaining two years of the study and the results of many previously published studies, which reported an increase in yield with increasing irrigation rate [67; 68; 69]. Given that the leachate level in the extremely rainy year exceeded the MAC only in the springtime, it can be assumed that the decrease in yield from the a3 irrigation treatment was the result of the excessive amount of SWC due to the irrigation water. The upper soil layer in which the sensors were placed (\(<\)30 cm) was dry for a short time (Figure 2, end of July and beginning of August), because of which, the GMS readings indicated that the SWC in the upper soil layer was below the FC (Figure 4). As previously presented by [PERSON] et al. [29], irrigation water decreases the accessibility to oxygen in the maize root zone and induces stress; therefore, the yield of the a3 irrigated treatment was significantly lower. Although the groundwater level and the SWC at the mentioned time were lower compared to the rest of the maize-growing period, the development stage of the maize, i.e., the depth of the root system, should be taken into account. Our results showed that the maize root system could draw water from deeper layers of soil, i.e., a depth greater than 30 cm, than where the sensors were placed, and that the additional irrigation caused water-induced stress due to an excessive SWC. The result of the IWUE analysis confirmed this statement (Table 4) since the higher irrigation rate reduced the maize IWUE in the extremely wet growing season for both N fertilizer treatments. One should not ignore the fact that the IWR analysis showed that even during the extremely wet growing season, the lack of water during July and August should be compensated (Figure 5). Furthermore, an interesting finding was that there was almost the same IWR during the extremely dry and average year, which came as a result of the extremely high air temperatures during the last study year, i.e., the high ETc rate. Additionally, our results demonstrate two things. First, the installation of the GMS should be adjusted to extreme weather conditions, i.e., high amount of rainfall in a short period, potential waterlogging, and the groundwater level. Second, this adjustment should also consider the crop growth stage, i.e., the root depth. Here, it is important to keep in mind that our study design was to schedule irrigation events according to SWC measurements found with the GMS. This may be considered as a potential limitation in environmental or field studies, where one factor cannot be completely separated from others, i.e., where the study factors are closely related to external factors that cannot be influenced. Another limitation that should be addressed is the fact that some observations and data collection were limited by the field conditions, for example, heavy rainfall and waterlogging during extreme weather events. From the results of [PERSON] and [PERSON] [70], it is clear that the degree of the water supply of maize can only be adequately judged based on the degree of the nutrient supply. The results from our study provide evidence that the amount of leached nitrate increased with increasing irrigation and nitrogen fertilizer rate regardless of the weather conditions (Figure 11). However, it is important to emphasize that the highest amount of leached nitrates in the extremely wet year was in the springtime (Figure 12), which occurred as a result of excessive rainfall (Figure 2) and a high N fertilizer rate. This statement was confirmed using correlation analysis, which showed a stronger positive connection between the leached nitrate and N fertilizer rate compared to the irrigation rate (Figure 12), regardless of the weather conditions.