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In this study, the effect of biochar, leonardite and coal was investigated on humification and germination index, and the concentration of some elements in the co-composting of manure and forest organic materials. The experiment was conducted in a factorial design with two factors, namely treatments at two levels (2 and 4% by weight) mixed with the raw materials and time was the second factor. Sampling was carried out during the composting process in the first to 12 weeks, measuring temperature, EC, C/N ratio, nitrate, and total concentrations of P, K, Ca, Mg, Na, Fe, Zn, Cu, and Mn, humification and germination index in the compost. The results showed that the coal (2%) had the highest temperature, while the leonardite (2%) had the longest thermophilic phase period. The coal (4%) led to a significant increase in EC, and biochar increased nitrate concentration and C/N ratio. The addition of leonardite resulted in a significant increase in humic and fulvic acids concentrations, as well as the highest values of humification and of polymerization index. The additives did not have a significant effect on germination index and the E3/E5 and E4/E6 ratios. The control had higher concentrations of measured elements compared to other treatments. The results of this study suggest that considering the cost of raw materials, coal is a suitable treatment for accelerating the production and improving the quality of compost, and leonardite, due to its high humic substrate, can be used at the end of composting for the enrichment of the produced compost. [ABSTRACT FROM AUTHOR]

Background and Objective: It is important to determine the quality of the compost to use compost properly. The aim of this study was to determine the effect of mixing ratio of bulking agent on stability and maturity indices in poultry waste compost. Materials and Methods: Two piles of sawdust mixture with poultry wastes and volume ratios of 1:1 (W1) and 2:1 (W2) were prepared by Windrow method and a pile containing poultry manure was used as control (W0). In order to determine the stability and maturity indices in compost, the most important physicochemical and biological parameters were studied. Results: The thermophilic phase lasted about 7 weeks for W1 and about 4 weeks for W2. The initial C/N ratios in the W0, W1 and W2 were 27.10, 31.40 and 56.24, respectively, which eventually reached less than 20. The reduction of organic matter in the three piles was 8.30%, 62.59% and 85.53%, respectively. The thermophilic phase caused a sharp decrease in the population of indicator and pathogenic microorganisms in all piles. The highest dehydrogenase activity in W1 pile was 2.95 mgTPF/gDW.h and by decreasing temperature until the last day, its value decreased to 0.29 mgTPF/gDW.h. Conclusion: The best ratio for mixing sawdust with poultry manure was 1:1 (v:v). Microbial and enzymatic activities are useful parameters for monitoring poultry composting process and determining the rate of compost stability, and the use of this compost in agriculture will improve soil quality. [ABSTRACT FROM AUTHOR]