Effect of biochar amendment on compost organic matter composition following aerobic composting of manure

Abstract

Biochar, a material defined as charred organic matter applied in agriculture, is suggested as a beneficial additive and bulking agent in composting. Biochar addition to the composting feedstock was shown to reduce greenhouse gas emissions and nutrient leaching during the composting process, and to result in a fertilizer and plant growth medium that is superior to non-amended composts. However, the impact of biochar on the quality and carbon speciation of the organic matter in bulk compost has so far not been the focus of systematic analyses, although these parameters are key to determine the long-term stability and carbon sequestration potential of biochar-amended composts in soil. In this study, we used different spectroscopic techniques to compare the organic carbon speciation of manure compost amended with three different biochars. A non-biochar-amended compost served as control. Based on Fourier-transformed infrared (FTIR) and C nuclear magnetic resonance (NMR) spectroscopy we did not observe any differences in carbon speciation of the bulk compost independent of biochar type, despite a change in the FTIR absorbance ratio 2925cm/1034cm, that is suggested as an indicator for compost maturity. Specific UV absorbance (SUVA) and emission-excitation matrixes (EEM) revealed minor differences in the extractable carbon fractions, which only accounted for ~2-3% of total organic carbon. Increased total organic carbon content of biochar-amended composts was only due to the addition of biochar-C and not enhanced preservation of compost feedstock-C. Our results suggest that biochars do not alter the carbon speciation in compost organic matter under conditions optimized for aerobic decomposition of compost feedstock. Considering the effects of biochar on compost nutrient retention, mitigation of greenhouse gas emissions and carbon sequestration, biochar addition during aerobic composting of manure might be an attractive strategy to produce a sustainable, slow release fertilizer.

Nutrient effect of various composting methods with and without biochar on soil fertility and maize growth

“…This was not found in the study conducted by Glaser et al (2015). In addition, during bokashi fermentation, most of the nutrients are preserved in the hermetic fermentation pack, unlike conventional (open condition) and aerobic composting (piles sheltered with rooftop but open from side) that were subjected to nutrient leaching and elemental losses in the rainy season (aerobic piles mainly affected by lateral rainfall) during which composting took place (Hagemann et al 2018). Beneficial effects of co-composted biochar on soil physicochemical properties and available nutrients (P-AL, K + , NO 3 − ) have previously been reported by Agegnehu et al (2016).…”

“…Both aerobic composting heaps were kept in the shade of a shelter to provide protection from rainfall and to ensure optimum humidity conditions required for good quality compost. Aerobic compost was matured by manual turning the composting piles daily for the first three weeks, and every three d after that (Hagemann et al 2018). For bokashi fermentation, raw materials from two heaps (with and without biochar) were placed on two separate plastic sheets in layers (six layers in total for each heap).…”

The Efficiency of a Low Dose of Biochar in Enhancing the Aromaticity of Humic-Like Substance Extracted from Poultry Manure Compost

“…It should be noted that the extraction method of the humification is complementary to the analysis of the bulk organic matter, and it can cause a bias to the analysis of the chemical composition of the humic substance [47]. To consider this matter, monitoring the chemical and physical property of bulk compost [48] together the segmented study of humified organic matter would be a holistic approach. However, the extraction method has the advantage to overcome the limitation of the presence of small particles of biochars in composting that can be hardly removed from the compost matrix before the analysis.…”

Effects of Biochar on the Net Greenhouse Gas Emissions under Continuous Flooding and Water-Saving Irrigation Conditions in Paddy Soils

“…Biochar can reduce greenhouse gas emissions [7,8] and increase the carbon storage [9][10][11][12]. Biochar is defined as charred organic matter produced by pyrolysis.…”