The Performance of Mesotrophic Arrhenatheretum Grassland under Different Cutting Frequency Regimes for Biomass Production in Southwest Germany
2019
Moritz von Cossel | Andrea Bauerle | Meike Boob | Ulrich Thumm | Martin Elsaesser | Iris Lewandowski
Biogas production is a key renewable energy pathway for a more sustainable future bioeconomy. However, there is a crucial trade-off between biomass productivity and social-ecological sustainability of available biogas cropping systems. Permanent grassland has been frequently promoted as a promising perennial cropping system for biomass production. Three- and four-cut regimes are usually the highest-yielding and thus preferable for biogas production. A three-year field trial in southwest Germany investigated biomass yield and biochemical composition of mesotrophic Arrhenatheretum grassland under three cutting regimes (two-, three- and four-cut). For the three-cut regime, a preliminary biogas batch test was conducted. The three-cut regime had the highest annual accumulated dry matter yield (11.8−14.8 Mg ha<sup>−1</sup>), an average specific methane yield of 0.289 m<sup>3</sup><sub>N</sub> kg<sup>−1</sup> volatile solids<sup>−1</sup> and an accumulated annual methane yield of 3167−3893 m³<sub>N</sub> ha<sup>−1</sup>. The four-cut regime performed least favorably due to a lower dry matter yield than the three-cut regime, the highest ash content and the highest nitrogen content. Thus, the three-cut regime promises the best yield performance, whereas the two-cut regime can potentially provide more ecosystem services such as biodiversity conservation and wild-game protection. Consequently, the two-cut regime could help improve the social-ecological sustainability of biogas crop cultivation.
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