# Carbon Storage Potential and Carbon Dioxide Emissions from Mineral-Fertilized and Manured Soil
## 4 Discussion
### Co\({}_{2}\)-C Soil Emission  
Regardless of the soil fertilization, our study showed a very high temporal variability of the daily CO\({}_{2}\)-C soil emissions (Table 3), which was typical for gas emissions from the soil [21; 25; 43; 44]. The average daily CO\({}_{2}\)-C emissions from the soil measured in the Ca + M treatment was 41.7% and 72.1% higher than in the CaNPK treatment in the first and second year of the study, respectively. In the first year, higher CO\({}_{2}\)-C emissions from the Ca + M than from CaNPK-treated soil were observed in mid-April, between the end of May and mid-June, and from the beginning of August until the end of the study period (Figure 4). In the second year, on almost all the measurement dates, the CO\({}_{2}\)-C emissions from the Ca + M-treated soil were higher than those from soil that only received mineral fertilizer. In both years, the differences were statistically significant (Table 3). Higher CO\({}_{2}\)-C emissions from the manured soils than from the mineral-fertilized soils might indicate a higher importance of heterotrophic CO\({}_{2}\)-C emissions resulting from the decomposition of organic matter by soil microbes (bacteria, fungi). Soil heterotrophic CO\({}_{2}\)-C emissions are considered one of the most significant components of carbon cycling, affecting the soils' limited importance in carbon sequestering [37; 45]. The scientific literature thoroughly addressed the effect of mineral and organic fertilization on soil CO\({}_{2}\)-C emissions. The relationship between CO\({}_{2}\)-C soil emissions and the different mineral fertilization strategies was analyzed by [PERSON] et al. [24]. In their study, the CO\({}_{2}\)-C soil emissions in the NPK treatment were 73.9%, and the NP (no potassium) treatment was 57.3% higher than the NIL treatment (non-fertilized soil). In comparison to the NIL treatment, the CO\({}_{2}\)-C soil emissions in the PK (no nitrogen) and NK (no phosphorus) treatments were only 10.1% and 5.5% higher, respectively. N-fertilization increased plant growth and the soil microbial activity affecting higher CO\({}_{2}\)-C soil emissions [46]. [PERSON] et al. [18] reported that CO\({}_{2}\)-C soil emissions increased by approximately 14% after nitrogen fertilizer application at a dosage of 150 kg N ha\({}^{-1}\). On the contrary, a very low increase in CO\({}_{2}\)-C soil emissions after an NPK application was recorded by [PERSON] et al. [47]. However, [PERSON] et al. [48] and [PERSON] et al. [49] reported that the mineral fertilization did not have an effect on the CO\({}_{2}\)-C soil emissions. However, at a rate of 300 kg N ha\({}^{-1}\), CO\({}_{2}\)-C soil emissions declined due to a lower enzyme activity in the soil [50]. A decrease in CO\({}_{2}\)-C soil emissions by 10% was recorded after an N-fertilization in the study by [PERSON] et al. [14]. Similar data were obtained by [PERSON] and [PERSON] [20]. In summary, most studies showed a significant effect of the fertilization on CO\({}_{2}\)-C soil emissions. The differences between the study results illustrate the need for further studies on the efficiency of the available fertilization strategies to reduce emissions and mitigate climate change. There is scientific evidence that manure affects CO\({}_{2}\)-C soil emissions [47; 49; 51]. CO\({}_{2}\)-C soil emissions increased sharply following the manure application [41]. In our study, manure was applied in autumn before the rye sowing (Ca + M). Compared to the CaNPK treatment, an evident increase in CO\({}_{2}\)-C soil emissions due to manuring was mainly observed in the autumn of the first year. [PERSON] et al. [24] stated that at an annual mineralization rate of 24-36%, manure increased CO\({}_{2}\)-C soil emissions by 16% compared to mineral fertilization. [PERSON] et al. [25] and [PERSON] et al. [41] reported that, regardless of the type of manure, the CO\({}_{2}\)-C soil emission rate increased with the manure dosages.