LAUSR

Abstract Tall wheatgrass ( Agropyron elongatum ) has been proposed as a new energy crop of a dry matter yield (DMY) and methane hectare yield (MHY) potential similar to maize. So far, little is known about the agronomy of the grass for biogas production in temperate Europe. In a field trial the hypothesis was tested that aboveground DMY and MHY are affected by the frequency of cutting and cutting height, and that these management effects interact with the tall wheatgrass germplasm. Four wheatgrass provenances were sown in a three-factorial block design with three cutting heights at harvest (5, 10, and 15 cm above soil surface) and three levels of cutting frequency (one, two, and four cuts year −1 ). Aboveground DMY (two full harvest years), crude nutrient and fibre content as well as the specific methane yield (SMY, one full harvest year) and MHY were determined. 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 Nm 3 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.