## 4 Results
### Nitrogen Uptake by Ryegrass Fertilised with Kitchen Waste-Based Fertilizers
All standard errors were lower than 0.5 (30 days), 0.3 (60 days), 0.4 (90 days), and 0.05 (120 days), thus not visible on the plot. should be applied according to EU and PL regulations to utilize potential salmonella eggs, _E. Coli_, and other pathogens does not have as much of a substantial effect as EM addition. The mineral fertilizer data were not displayed in Figures 1-3 because cow manure granulated as organic fertilizer serves as a more representative reference for kitchen waste-based organic fertilizers, especially that agronomic effectiveness in terms of N use per ha of MF is ca. 2.5 times higher (49.3) than CMG (20.3). Mineral fertilizer data are presented in a cumulative way in Figure 4 to generally show their higher effectiveness; these data are also used in Figure 7 when RAE is calculated. Figure 5a shows the ryegrass growth dynamics across treatments for four subsequent harvests. Generally, 40-50% of the biomass was formed during the second month, 20-30% of the biomass during the third month, whereas ca. 10-15% each during first and fourth months. This was probably due to a combination of already well-developed root zones, temperature/lighting (mid-May to mid-June) conditions, and availability of nutrients. Only the control treatment (without any fertilization) expressed more even distribution of biomass in the first three months, probably due to nutrient scarcity, and stress factors resulting in rapid biomass accumulation in the first month. Among all experimental treatments, DKW ST-dig provided the highest total cumulative yields reaching 35 g TS/pot with CMG reaching a slightly higher value of the 38 g TS/pot. No significant differences in growth dynamics over time were noticed across treatments, with reference fertilizers MF and CMG working a bit faster for the first month already (15-20% of the biomass versus 7-15% for kitchen waste treatments). Figure 5b shows the N utilization dynamics across treatments for four subsequent harvests. Generally, 35-45% of the nitrogen was utilized during the second month, 20-40% during the first month, whereas ca. 20-40% during the third and fourth month together. Only the control treatment expressed the largest share of N utilization in the first month (up to 60%). Among all experimental treatments, DKW ST-dig provided the highest total cumulative N utilization rate reaching 350 kg N/ha with CMG reaching a slightly higher value of 390 kg N/ha. Among the organic materials, CMG provided over 40% of N utilization in the first month, whereas step-wise treatments of kitchen waste also improved this share, namely, 20% for KW 1M, 25% for DKW-ST, 28% for DKW 2 EM, 30% for DKW 1 EM ST, and 35% for DKW ST-dig. This proves that the suggested treatment  
Figure 4: Cumulative nitrogen use from 1 ha of ryegrass fertilized with kitchen waste-based fertilizers, compared to the commercial organic fertilizer (CMG)—(**left**) and to commercial mineral fertilizer (MF)—(**right**), cumulative data for 30, 60, 90, and 120 days harvests. Please note different scale on the right plot. All standard errors were lower than 1.5, thus not visible on the plot. brings the kitchen waste agronomic characteristics closer to the behavior of commercial organic fertilizer.