**5. Conclusions**

The decisive factors determining sugar beet beetroot and top yield were weather conditions. During the years with relatively good (2016) and good (2017) conditions, the beetroot and top yield was on average 70 t ha−<sup>1</sup> and 28.7 t ha−1, respectively. In the extraordinary dry year of 2018, the average beetroot and top yield decreased to 44 t ha−<sup>1</sup> and 12 t ha−1, respectively.

The application of FYM at a dose of 21 t ha−<sup>1</sup> significantly increased the beetroot and top yield, if we evaluate the entire period (2016–2018). In individual years, we recorded a significant difference only in the case of beetroots, in 2016. In general, the yields with FYM treatment were always higher than in the case of the non-fertilized control.

The application of mineral fertilizers significantly increased beetroot and top yield as compared with the unfertilized control. According to the results of the linear-plateau model, a suitable N dose is 112 kg ha−<sup>1</sup> with a corresponding yield of 66 t ha−1. This model took into account the average yields of years including standard and unsuitable climatic conditions.

In the case of the joint application of FYM and NPK, we did not record a significant increase in yield as compared with NPK applied alone.

The sugar content and the concentration of chemical elements in the beetroots and the tops were not significantly affected by the fertilization treatment, except for slightly higher concentrations of P in the tops.

The application of NPK in the soil resulted in lower pH values than we observed in the control and FYM treatments. The combined application of FYM and NPK slightly reduced the negative impact of NPK on soil pH. The application of NPK, FYM, and especially the combination of NPK and FYM significantly increased the content of Corg, P, and K in the soil.

**Author Contributions:** Conceptualization, L.H., L.M., and E.K.; methodology, L.H. and E.K.; software, L.H., and K.K.; validation, L.H., L.M., and K.K.; formal analysis, L.H., and K.K.; investigation, L.H., L.M., E.K., and K.K.; resources, L.H., and E.K.; data curation, L.H., and E.K.; writing—original draft preparation, L.H.; writing—review and editing, L.H.; visualization, L.H., and K.K.; supervision, E.K.; project administration, L.H., and E.K.; funding acquisition, E.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Ministry of Agriculture of the Czech Republic, gran<sup>t</sup> number RO 0418.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Data sharing not applicable.

**Acknowledgments:** We would like to thank the technicians who participated in the experiment and analyses.

**Conflicts of Interest:** The authors declare no conflict of interest.
