Threats and opportunities of different bioenergy production systems for the soil organic carbon stocks in agricultural soils in Flanders

General introduction

In this study we assess threats and opportunities of different bioenergy production systems for the soil organic carbon stocks in agricultural soils in Flanders. Energy crops may negatively affect soil organic carbon stocks in agricultural soils as aboveground biomass is removed to be used for bioenergy production. We determine the effect of the most important (potential) bioenergy production processes in Flanders by modelling the soil carbon cycle. Short and long term effects on soil organic matter are assessed and compared with conventional crop rotations.

Research approach

We make an inventory of energy crops, residual biomass streams and by-products of agriculture in Flanders. Important potential energy crops are rapeseed, Miscanthus, energy maize and short-rotation coppice. The corn stover is an important source of organic carbon in crop rotations but is also a potential feedstock for bioenergy production. We collect data on crop yields and crop residue biomass, along with their (bio)chemical composition. For a selection of crops we assess the contribution of aboveground crop residues and roots to soil organic matter. We evaluate how biochar and compost can be used to maintain soil organic carbon stocks in agricultural soils.

Relevance/Valorisation

The environmental, agricultural, energy and climate policy points of view all have different views on soil organic matter. According to the thematic soil strategy, soil organic matter is of prime importance for maintaining soil functions. However, the European Nitrate Directive limits the input of organic matter into soils. The Common Agricultural Policy is stimulating practices that result in maintenance of the soil organic matter levels. Biomass is considered to be an important energy source and also as a way to reduce CO2 emissions within the energy policy. The climate policy aims at increasing the storage of carbon in soils. Soil organic matter is considered to be an important carbon sink because carbon is stored for longer periods in the soil.