Identifying crop candidates for biorefinery – progress and challenges
By Kiril Manevski and the team in BioValue Project 1 from Aarhus University, Dept. of Agroecology
The majority of the agricultural systems under temperate climate are modern, but increasing demand for biomass, including supply for biorefinery, calls for new and more productive cropping systems. We investigate agro-ecological and environmental features of potential crop candidates for biorefinery in Denmark with the aim of sustainable intensification, which in popular terms means “more with less”.
The results show high biomass yield for cropping systems optimised for biomass supply compared to traditional cropping systems in Denmark (Fig. 1). Some perennial crops are fertilised with large amounts of nitrogen (400-500 kg N ha-1 year-1) and they are able to take it back by producing high biomass yield and N content at low environmental cost. These results also point on opportunity for the farmer to diversify cropping systems, though this should be supported by a sound agro-economic analysis in relation to market demands, production costs and biomass prices, all of which affect farmer decision whether to grow the crops or not.
Fig. 1. Annual biomass difference of optimised rotations and perennial crops from traditional cropping systems (in bold). Results are for Foulum in Denmark (sandy loam soil, experiments started in 2012-establishment year).
Improving crop simulation models with parameterisation
Our work also involves process-based (Daisy) modelling of agro-ecosystem dynamics. We simulate the annual biomass yield, nitrogen uptake, root zone water- and N dynamics for majority of the satisfactorily. For many perennial crops, however, Daisy, as most other models, lacks parameterisation, and the use of “proxy” crops imposes challenges to accurately simulate their growth and re-growth after cuttings within a year (Fig. 2). Hence, our work sets a valuable platform for adaptation of models to new crops or for the improvement of existing crop parameters set. On a recent participation at iCROPM (www.icropm2016.org), we exchanged ideas with other scientists on how crop simulation models can be improved and applied in better support of agricultural production and food security under global change. We also participate on EcoSummit (www.ecosummit2016.org) by addressing the interacting effects of plant species and field management, and how these can be utilised to “enhance” important plant growth characteristics, such as light interception and conversion into biomass.
Fig. 2. Measured versus Daisy-simulated biomass yield of annual and perennial crops at Foulum in Denmark (sandy loam soil, 2012-2015).
Main challenges in simulating biomass supply to biorefineries
Some of the major challenges associated with our work include the need for relevant and sufficient field data on plant phenology and root dynamics, as well as winter mortality and recovery from stress for the perennial crops, which can also be used to improve the simulation of their dynamics. In addition, nitrous oxides emissions are not included in our study but may play important role in evaluating the sustainability of the cropping systems.