Biochar

Photo: ATB

Biochar

Energy source, peat substitute and soil additive - an all-rounder with climate protection potential

 

In view of the urgent global challenges, it is necessary to break new ground for agriculture and horticulture in order to ensure a sustainable and at the same time long-term preservation of soil humus content and its fertility and thus to contribute to climate protection. 

Carbonisation as a contribution to climate protection

A promising approach to carbon sequestration is the thermal stabilisation of carbon compounds resulting from incomplete combustion of biomass. Thermochemical treatment (pyrolysis and hydrothermal carbonisation) can be used to carbonise both woody and unwoody biomass to form biochar, thus protecting it from rapid microbial degradation. 

Biochar - additives for the soil

In connection with the recycling of agricultural waste streams, ATB is researching on strategies for the production of agents for the soil with a positive effect on the soil water balance in order to mitigate the effects of droughts, contribute to the sequestration of CO2 and sequester carbon in the soil.

Terra preta is a good example in this respect. This fertile black soil, which has been formed in the Amazon basin over centuries, is characterised by the fact that it stores large quantities of nutrients and organic carbon.

Biochar as substitute for peat

Agriculture and horticulture contribute significantly to increasing the climate-damaging content of carbon dioxide (CO2) in our atmosphere. Carbon-rich peat deposits in wetlands play a key role in this context. Their extraction and horticultural use leads to the unavoidable release of CO2.

Alternative materials such as composts, wood fibres or biochar could replace peat in substrates for cultivated plants in the future. Biochars offer great potential for this, partly because they have similar low pH and conductivity values as peat. Peat substitutes should feature the lowest possible nutrient and lime content, low N immobilisation, loose storage and high structural stability, as well as a high air capacity and sufficient water storage capacity.

With our research work in ATB's biochar lab we are currently investigating to what extent chars from pyrolysis and hydrothermal carbonisation (HTC) can be used as alternative substrates to supplement or even replace the peat used in growing media.

In the case of HTC carbons, furfurals and phenols, which may be generated depending on the process conditions, must be removed. In order to meet the quality criteria for peat replacement in growing media, we develop further post-treatments of the chars and evaluate their effectiveness by means of germination tests.

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Expert on this topic

Dr. habil. Libra, Judy

scientist, group leader of the Biochar work group


Department: Post Harvest Technology

Email: jlibra@spam.atb-potsdam.de

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Expert on this topic