## 1 Introduction
### Determination of Compost Quality and ITS Measurement  
According to [PERSON] [24], the quality of compost is mainly determined by the kind and composition of input materials, the degree of purity and quality of soil, and emissions in the specific area of collection. He also highlighted that compost quality is substantially influenced by the type of technology applied during the composting process. However, his findings related to the importance of treatments during the composting were not substantiated by [PERSON]'s [25] examination. The determination and evaluation of compost quality can be carried out by examining physical (e.g., color, odor), chemical (e.g., C/N ratio, nitrification), and microbiological parameters (e.g., self-heating test, respiration), and parameters that influence its effect on the grown crops (e.g., germination test) [26]. Considering the abovementioned, in the case of the quality of backyard compost, these parameters are advisable to examine and are determinant during backyard compost use. The parameters are as follows: maturity and stability, which has a direct effect on plant development; macro and micronutrient contents, which contribute to the nutrient replenishment; toxic element contents, which determine the safe use of composts; and the weed seed content, which influences the long-term weeding effect of backyard composts and as such is a very practical quality parameter. Maturity can be characterized by physical, chemical, and biological stability [27]. Stability refers to the microbial activity in compost, and is evaluated by respirometric measurements or by analysis of the changes in chemical properties [28]. Furthermore, stability can be evaluated by using biological methods such as the germination index (GI) [29; 30; 31]. It should be noted that the principle of microbiological maturity tests depends on the assumptions that the maturity of composts is strongly related to stability, and that the microbial activity of composts determines their maturity [32; 33]. The different maturity levels of composts depend on the alteration of the different components, the extent and quality of humification and mineralization processes, and the degree of decomposition of the original organic materials [34].The examination of the respiration of composts is an adequate method that can be applied as a test for microbiological compost maturity [26]. The respiration examination can measure either the carbon dioxide evolution or the consumed oxygen during the biological decomposition of the compost samples. Several studies considered oxygen consumption as a reliable variable for evaluating the development of composting due to its correlation with the metabolic potential of compost [6; 35; 36]. Additionally, oxygen is directly responsible for the oxidation of organic matter [8]. This can be measured through respirometry, a recognized method for measuring the oxygen consumption of microorganisms [37]. In the case of this technique, two methods can be differentiated, i.e., the static and the dynamic methods. The differentiation depends on the whether the measurements are carried out with or without a continuous oxygen supply [35; 38; 39]. The so-called AT\({}_{4}\) value is an internationally accepted method to determine the maturity, stability, and usability of composts. It measures the total amount of oxygen that is consumed by the microorganisms during the biological decompositions of the biologically degradable organic matter contained in the samples within four days of examination (examined parameter: respiration activity, oxygen demand, unit: mg \(O_{2}/g\) dry matter) [39; 40; 41].