Quantifying the economic and greenhouse gas balance advantages of establishing miscanthus from stem cuttings

The establishment of miscanthus conventionally propagated from rhizome pieces is an expensive and carbon intensive process. A method to establish miscanthus crops through harvesting stem segments in autumn and sowing directly into a field can provide a low cost alternative to rhizome propagation. This study aims to assign both economic and GHG intensity values to the system in comparison to rhizome propagation. This study employed sensitivity analyses to investigate the effect of nitrogen rate and three different stem segment sowing densities. The cost of harvesting plant material and sowing 1 ha was found to be 1703 € for conventional rhizome propagation and 810 € for the autumn harvest and direct sowing stem nodal propagation system. This study also found considerable reductions in the GHG emissions of the stem based system which were 535 kg CO2 equivalent compared to 2118 kg CO2 equivalent for conventional rhizome propagation. Sensitivity analysis of the stem based system found that at the highest stem sowing rate of 39 999 ha-1 and applying 150 kg nitrogen ha-1 would increase cost to 976 € ha-1 with emissions of 1151 kg CO2 equivalent. At the lowest stem sowing rate of 13 333 ha-1 and the application of 0 kg N ha-1 to the mother crop an expense of 809 € ha-1 was incurred with emissions of 513 kg CO2 equivalent. There are significant economic and GHG advantages of moving from a rhizome based propagation system to a stem based propagation system.