The interaction of plant derived charcoal with biogeochemical cycles in natural and agricultural ecosystems
Simona Castaldi
DISTABIF, Università degli Studi della Campania “Luigi Vanvitelli”, Caserta, Italy
Charcoal is a product generated by the combustion of plant material at high temperatures in limited conditions of oxygenation. Production of charcoal might occur in natural ecosystems following strong fires or is accomplished via pyrolysis to produce the so-called biochar, which has been proposed as an agricultural amendment.
The impact of the char molecule on biogeochemical cycles and in particular on C and N cycles is strongly dependant on the ecosystem, as it can either stimulate or reduce nutrient losses and GHG emissions. Fire-charcoal interactions of the plant-soil system in boreal forests might have a significant acceleration effect on organic matter decomposition and subsequent mineral and gaseous losses, due not only the direct effect of fire but also to the chemical properties of charcoal, which can interact with phenolic compounds which contribute to tight the C and N cycle in boreal ecosystems.
On the other hand, biochar application in agriculture might significantly improve several soil characteristics leading to a reduction in GHG emissions, increased retention of nutrients and lower C footprint of the agro-products. The overall impact on agroecosystems depends on many factors, including biochar material, soil characteristics, redox conditions, climatic parameters. Biochar application has been demonstrated to improve soil conditions for microbial and plant growth in water limited ecosystems, however, biochar might also prove an interesting amendment in water saturated and poorly oxygenated soils like those occurring under boreal climate, although more research is needed to test this hypothesis.