Diversifying the utility and species composition of Nordic forage systems : new fractionation methods and novel legume species

Abstract

Leys, a temporary grassland grown as part of a crop rotation, represent an essential component of agricultural production in the Nordic countries. This thesis explores methods to diversify the utility of feed produced from leys through fractionation, as well as increase the diversity of legume species within the stand. Two fractionation methods, press juicing and leaf stripping, were assessed in tandem on pure legume stands, with juicing producing a biorefined fraction with a lower neutral detergent fiber (aNDFom) content than leaf stripping. Both methods demonstrated variability in crude protein (CP) and biomass allocation to the resulting fractions, likely influenced by stand characteristics and machine functionality. Leaf stripping fractionation was tested on mixed grass/legume stands and produced a biorefined fraction with a higher CP content and digestibility and a lower aNDFom concentration than the mixed sward if harvested conventionally. In order to increase the biodiversity of leys, wild legume species native to northern Sweden were evaluated for their agronomic potential using botanical resources, such as herbaria, floras, and databases. Following the selection process, seven wild legume species were selected, with early flowering species being preferred due to their ability to provide floral resources early in the season, when pollinator resources are sparse in agricultural landscapes. Four of these seven species were subsequently studied when grown in mixed stands with timothy grass. Two of the species, Vicia sepium and Vicia cracca maintained promising nutritive value across multiple harvesting frequencies, though additional years of data collection are needed to assess their potential for inclusion in leys.