Tall wheatgrass (Agropyron elongatum) for biogas production: Crop management more important for biomass and methane yield than grass provenance

In general, only small differences in the target variables among the different provenances were found. Likewise, a significant interaction of provenance x crop management was only found for the DMY in the second year. The cutting frequency strongly affected the DMY with a two-year average of 14.6, 18.4, and 14.9 t DM ha−1 and the MHY of 3505, 5705, and 5384 Nm3 methane ha−1 for the one-, two-, and four-cut regime, respectively. The cutting height was less important with DMY values of 17.2, 16.3, and 14.4 t DM ha−1 for 5, 10, and 15 cm cutting height, respectively. SMY was well predictable from growing degree days. In conclusion for Central European conditions the performance of tall wheatgrass is suitable for biogas production and clearly responds to cutting frequency and cutting height with highest DMY and MHY in the two-cut system and 5-10 cm cutting height. The choice of the wheatgrass germplasm was less important. It remains to be shown for how long tall wheatgrass stands will maintain their performance.