Miscanthus establishment and management on permanent grassland in southwest Germany

Abstract

The intensification of livestock farming and use of arable forage crops has led to a decrease in the area of grassland used for animal husbandry. One potentially profitable use of this grassland is the production of biomass for bioenergy. The C4 grass miscanthus (Miscanthus spp.) is considered an important biomass resource for bioenergy production; however, its cultivation is currently limited by the shortage of suitable agricultural land. The establishment of miscanthus on permanent grassland, at low densities and without destruction of the existing vegetation, could be an interesting option to consider. In this way, the expansion of miscanthus cultivation could be combined with grassland maintenance. Conventional tilling practices in miscanthus establishment (ploughing and herbicide application) on meadows can lead to loss of biodiversity. The aim of this study was to investigate efficient no-till practices for establishment and maintenance of several miscanthus genotypes on permanent grassland in Germany, focusing on the methods to improve establishment success and biomass production potential of miscanthus-supplemented grassland. A field trial was conducted at two sites to assess the effect of genotype, grassland pre-treatment (through temporary suppression of existing vegetation to reduce initial competition) and management (harvest frequencies) on miscanthus establishment and growth in grassland stands. An additional experiment with two miscanthus genotypes was set up to assess the effect of propagation method (rhizomes or pre-grown plantlets) on miscanthus establishment on grassland. Successful miscanthus establishment was achieved with no-till planting and grassland pre-treatment. Overall, miscanthus genotypes with tall, thick shoots performed better on grassland than those with short, thin shoots. Higher establishment rates were achieved through the transplanting of rhizome-derived (pre-grown) plantlets than with direct planting of rhizomes. Cutting the grassland vegetation to a stubble height of 5cm and spraying herbicide in narrow strips before introducing miscanthus had beneficial effects on its establishment, without significant negative impact on grassland productivity. In the first three years of the study, two biomass harvests per growing season allowed a good total biomass yield from grassland to be achieved without significant impact on miscanthus growth.