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Many farms run livestock production along with a biogas plant. Priority is the effort to prepare high-quality feed and high-quality feedstock for the biogas plant. However, deciding which harvesting technique to choose seems a difficult task. In this study, the influence of harvest technique on silage quality and thus on the methane yield during anaerobic digestion was investigated. Maize was harvested for silage and shredlage production. Two-year results showed that the chemical composition of water leachate from silage and the total solids content did not indicate any significant differences between maize silage and shredlage. Methane yield in the first year ranged from 0.2735 ± 0.0095 m3/kgVS (maize silage) to 0.3024 ± 0.0090 m3/kgVS (shredlage) and in the second year from 0.3047 ± 0.0110 m3/kgVS (maize silage) to 0.3147 ± 0.0086 m3/kgVS (shredlage). Methane concentration in biogas did not show any significant differences for the two types of harvesting techniques in both years. The results showed that harvest technique had no additional effect on the methane content in biogas and thus on the methane yield.

In recent years, various substrates for increasing the production of biomethane are increasingly exploring. The effect of such substrates on methanogenesis is investigated mainly in small volume digesters. However, operating acetogenic biogas plants depending on substrates combinations and monitoring of microbial communities in the anaerobic digesters located in the Czech Republic have never been studied yet. The variation in the distribution of main acetogenic genera in eight biogas plants based on different input substrates ratio was studied. The genera composition was identified by sequencing of the 16S rRNA gene. In total, 33 genera of this group of microorganisms were found out. The highest percentage (30.2%) of acetogens compared to other biogas plants was observed in Modřice biogas plant with the input substrate biological sludge and primary sludge (50/50, w/w %). The smallest percentage (1.14%) and variation in the distribution of acetogenic microorganisms was found in Cejc biogas plant, with the input substrate maize silage and liquid pig manure (80/20, w/w %). For the biogas plant operator it would be important to know the composition of a consortium of anaerobic microorganisms that are present in anaerobic digesters (in two regions in the Czech Republic) processing different input combinations of a raw material. This paper characterizes the effect of the input raw materials on the variation in the distribution of the microbial community.

Different types of soil respond variably to biochar amendment. Soil structure and fertility are properties which strongly affect the impacts of biochar on soil fertility and microbial activity. A pot experiment with lettuce was conducted to verify whether biochar amendment is more beneficial in sandy soil than in clay soil. The nutrient content (carbon and nitrogen), microbial biomass carbon, soil respiration, metabolic quotient, and plant biomass yield were determined. The treatments were prepared by mixing silty clay loam (Haplic Luvisol) with a quartz sand in ratios of 0%, 20%, 40%, 60%, 80%, and 100% of sand, the same six treatments were prepared and amended with biochar (12 treatments in total). Soil carbon and nitrogen, microbial biomass carbon, and soil respiration were indirectly dependent on the descending sand ratio, whereas the metabolic quotient increased with the ascending sand ratio. The biochar’s effects were positive for total carbon, microbial biomass carbon, metabolic quotient, and plant biomass in the sand-rich treatments. The maximum biochar-derived benefit in crop yield was found in the 100% sand + biochar treatment, which exhibited 24-fold (AGB) and 11-fold (root biomass) increases compared to the unamended treatment. The biochar application on coarse soil types with lower fertility was proven to be favorable.

(1) Background: sewage sludge is a by-product of wastewater treatment, which needs to be managed appropriately, e.g., in composting processes. The application of municipal sewage sludge composts (MSSCs) as a soil amendment is a potential way to effectively manage sewage sludge. (2) Methods: this paper presents the results of a vegetation pot experiment undertaken to assess the suitability of Dactylis glomerata L. and MSSC in the aided phytostabilization technique when applied on soils from an area effected by industrial pressure; this is characterized by high levels of heavy metal (HM). The contents of HMs in the test plant (the roots and above-ground parts), as well as in the soil and MSSC, were determined via an atomic spectrometry method. (3) Results: the application of MSSC positively contributed to an increased production of plant biomass and an increase in the pH in the soil. Concentrations of Cu, Cd, Pb, Zn, and Cr were higher in the roots than in the above-ground parts of Dactylis glomerata L. The addition of MSSC contributed most significantly to the considerable reduction in Ni, Pb, and Zn contents in the soil after the experiment. (4) Conclusions: MSSC can support the phytostabilization of soils contaminated with high levels of HMs.

Objectives As a liquid organic fertilizer used in agriculture, digestate is rich in many nutrients (i.e. nitrogen, phosphorus, sulfur, calcium, potassium); their utilization may be however less efficient in soils poor in organic carbon (due to low carbon:nitrogen ratio). In order to solve the disadvantages, digestate enrichment with carbon-rich amendments biochar or humic acids (Humac) was tested. Methods Soil variants amended with enriched digestate: digestate + biochar, digestate + Humac, and digestate + combined biochar and humic acids—were compared to control with untreated digestate in their effect on total soil carbon and nitrogen, microbial biomass carbon, soil respiration and soil enzymatic activities in a pot experiment. Yield of the test crop lettuce was also determined for all variants. Results Soil respiration was the most significantly increased property, positively affected by digestate + Humac. Both digestate + biochar and digestate + Humac significantly increased microbial biomass carbon. Significant negative effect of digestate + biochar (compared to the control digestate) on particular enzyme activities was alleviated by the addition of humic acids. No significant differences among the tested variants were found in the above-ground and root plant biomass. Conclusions The tested organic supplements improved the digestate effect on some determined soil properties. We deduced from the results (carbon:nitrogen ratio, microbial biomass and activity) that the assimilation of nutrients by plants increased; however, the most desired positive effect on the yield of crop biomass was not demonstrated. We assume that the digestate enrichment with organic amendments may be more beneficial in a long time-scaled trial.