Third-Generation Biomass Crops in the New Era of De Novo Domestication
Publication: Agronomy for Sustainable Development 40, Article number: 27
The emerging bioeconomy will increase the need for plant biomass. We call for a third-generation of bioenergy crops, or biomass crops, to help move society towards a sustainable bioeconomy and global food security. Third-generation biomass crops should be capable of producing both food and raw materials. Such flexibility would allow farmers to respond to global markets and buffer global food security. At the same time, third-generation biomass crops need to increase the sustainability of agriculture. To reach such ambitious goals, new biomass crops have to develop de novo from promising perennial wild species.
The dilemma of devoting productive land to fuel vs. food has made bioenergy crops controversial. The critique of first-generation bioenergy crops is particularly strong . Crops such as maize, rapeseed, sunflower, sugar beet and wheat were domesticated for direct human consumption, or adapted for indirect human nutrition, through the feeding of farm animals. These crops produce large amounts of lipids or carbohydrates that are easily converted to fuels such as biogas, biodiesel or ethanol . However, the production of these annual crops is energy and/or labor intensive. Any energy inputs must be counted against the yield of energy from these crops. It is obvious that the heavy equipment used to till the soil and plant requires fuel and emits CO2, but there are other less obvious energy inputs including the fossil fuel-intensive production of nitrogen fertilizer , pumping of water for irrigation and the production of seed for annual replanting. As perennial crops do not require annual replanting and/or soil tillage, the balance between input and harvested energy could be massively improved . Glover et al. (2010), found that a harvested perennial grassland required a 11.75-fold lower energy input than nearby annual cropping systems, with similar output of biomass and protein per hectare . New perennial bioenergy crops were therefore sought.