Greenhouse gas mitigation effects of integrating biomass production into European agriculture.

As energy crop production on European croplands expands, driven by accelerating consumption of bioenergy, there is a pressing need to evaluate the environmental impacts associated with this production. The present study considers on-going yield increases as a means of boosting agricultural output which results in a limited need to convert nature areas and grasslands to additional cropland. For nine land-use variants, the study evaluates cumulative greenhouse gas emissions, net organic carbon fluxes from the soil, and abated emissions achieved by replacing fossil fuels for transport with biofuels. The main finding is that, in European agriculture, it is possible to combine large-scale biomass production with food production sustained at current levels, with limited direct or indirect land-use changes and while accomplishing significant net greenhouse gas mitigation. Maintaining the current (business as usual) agricultural system results in 4.9 GtCO₂-eq. of cumulative emissions by 2030. Intensified food production and energy crop production on freed cropland combined with mitigation measure implementation significantly reduces cumulative emissions for the annual crop groups of oil, starch and sugarbeet to 1.9, 1.5 and 2.1 GtCO₂-eq., respectively. By 2030, perennial energy crop production can mitigate cumulative emissions to a large extent, reaching negative emissions (i.e. net sequestration) for grass and wood crops of -3.3 and -4.5 GtCO₂-eq., respectively. For the variants compared to the baseline, nitrous oxide emissions will increase modestly due to higher fertilizer-application rates, though at improved efficiencies per unit crop quantity produced. Emission mitigation results partly from the temporary increase in SOC sequestration though mainly from replacement of fossil resources by biomass resources. The results indicate that research and policy efforts aimed at further increasing productivity can raise the output from existing European croplands while being able to reduce or mitigate emissions significantly. [ABSTRACT FROM AUTHOR]