Perennial grasses for sustainable European protein production

Abstract

Compared with annual grain and seed crops, the production of perennial crops reduces losses of nutrients, the need for pesticides, and supports soil carbon build-up. This may help implementation of the EU Water Framework Directive (WFD); the Nitrates Directive; and support the new EU greenhouse gas reduction goals for agriculture. Denmark has an especially vulnerable aquatic environment due to sandy soils, a long coast line, and high precipitation. Thus, fulfilling the WFD means some areas must halve their nitrate leaching, and radical changes are required to reduce losses while maintaining profitable crop production. National scenarios show that up to ten million tonnes of additional biomass can be sourced in Denmark without reducing food production or increasing the area under cultivation if a biorefinery industry is established. In one of the scenarios optimized for additional environmental benefits, a reduction of nitrate leaching equivalent to 23,000 tonnes N annually was estimated. This is approximately the reduction required by the WFD for Denmark. Even though much more organic matter will be mobilized for biorefining, soil carbon levels are estimated to be largely unchanged in the "environment" scenario. This scenario was achieved by converting approx. 9 % of agricultural land from annual crops into perennial grass. New experimental results support the anticipated increase in total biomass yield and reduction in nitrate leaching, when converting land currently used for grain crop production into grass production. Grasses and legumes have higher contents of protein with better quality (high lysine and methionine contents) than grain and seed crops. Thus, substituting imported soya bean protein with protein extracted from perennial grasses is an interesting option.