# The Quantity and Composition of Leachate from Hop Plant Biomass during Composting Process
## 3 Results and Discussion
### The Impact of Composting Procedure on the Leachate Quantity and Composition during Composting
Two-way ANOVA results for four monitored leachate parameters (ammonium (NH\({}_{4}\)), nitrate (NO\({}_{3}\)), total nitrogen (Total N), and total phosphorus (Total P)) were calculated, and corresponding [PERSON]'s multiple-range test results for each of the two factors, location and time stamp, are shown in Table 3. Two-factor interaction plots are shown in Figure 5.  
It was found that neither time stamp nor the interaction between time stamp and procedure had an s.s. effect on NH\({}_{4}\) at the 95% confidence level. The importance of the procedure is insignificant (\(p\)-value = 0.1735); according to the interaction plot, the lowest NH\({}_{4}\) values were obtained in pile ROZ, while they were higher in ZUP and highest in LES (with the exception of the Time stamp 1, where NH\({}_{4}\) was lower (1726 mg/m\({}^{2}\)) than in ZUP (3213 mg/m\({}^{2}\))). The study revealed that small particles and enough oxygen caused the fastest degradation of organic matter in the LES pile, and the biochar lacked the ability to absorb these quantities and prevent them from being lost, especially in the thermophilic phase. In our study, around 1% of biochar was added to hop biomass compost (11 kg/tonne). [PERSON] et al. [20] also reported that adding 1% of biochar to dead poultry and wood chips compost did not decrease leachate formation. On the other hand, adding 10-15% of biochar is considered optimum for composting, as reported by [PERSON] et al., [23]. The rationale of adding such high rates of biochar to composting biomass will be the subject of further investigation. In pile ZUP, a similar but slightly lower amount of NH\({}_{4}\) was lost. Pile ROZ had the lowest loss of NH\({}_{4}\), presumably because it was covered. According to [PERSON] et al. [24], the traditional Bokashi method produces a high amount of ammonia gas (NH\({}_{3}\)). However, [PERSON] and [PERSON] [25] found that using efficient, effective microorganisms as soil amendment reduces NO\({}_{3}\) and NH\({}_{4}\) leaching. The same tendency was also observed in pile ROZ, which had fewer elements leaching than the other two. If we compare time stamps, we can see that the majority of the NH\({}_{4}\) was lost in the second month of the process. When comparing this to the weather data, we can observe that there was more rain this month, indicating that, considering leachate, it would be prudent to cover the pile before larger amounts of rain are expected, as well as in the thermophilic phase, to prevent NH\({}_{4}\) loss. Figure 3: Dynamic of temperature in observed compost piles during composting from September to end of April. The red line represents hygiization at 55 \({}^{\circ}\)C.  
Figure 4: Leachate quantity over time (L/m\({}^{2}\)) in relation to the composting procedure (LES, ROZ, ZUP) and Time stamp (1—first month of the process, 2—second month of the process, 3—November–April). Figure 5: Leachate: Two-factor interactions; composting protocol (LES, ROZ, ZUP) and Time stamp (1, 2, 3). Since high levels of nitrates in water pose a risk to health, NO3 is a sensitive parameter [26]. In terms of NO3, time stamp has an s.s. influence (\(p=0.0121\)) on this parameter; whereas the differences between Time stamps 1 and 2 were negligible for all three procedures, NO3 values varied substantially for Time stamp 3--ZUP: 118,785 mg/m2, LES: 43,049 mg/m2, ROZ: 7849 mg/m2. The Time stamp \(\times\) Procedure interaction was insignificant. According to [PERSON] et al. [27], NH4 accounted for roughly 55% of the total N content in the early stages of fruit and vegetable waste composting, while NO3 accounted for less than 0.01%. A decrease in NO3 loss in the early stage of the process was also recorded, as were higher NO3 values in the late stage of the process, which can be attributed to nitrification. It is worth noting that the compost pile in the study conducted by [PERSON] et al. [27] had a roof