Miscanthus: European experience with a novel energy crop

Abstract

Miscanthus is a tall perennial rhizomatous grass with C₄ photosynthesis which originated in East Asia. This article provides an overview of the most important results and experience gained with miscanthus in Europe over the past 10 years. Field trials have been established throughout Europe from the Mediterranean to southern Scandinavia. Most reported trials have used a vigorous sterile clone Miscanthus x giganteus, which has been propagated vegetatively either by rhizome cutting or in vitro culture. Yields in autumn have been reported in excess of 30 t ha⁻¹ (12 t acre⁻¹) for irrigated trials in southern Europe. Without irrigation autumn yields of 10–25 t  ha⁻¹ (dry matter) can be expected. The quality of miscanthus biomass for combustion is in some respect comparable to woody biomass and normally improves by delaying harvesting until the spring, although harvestable yields are thus reduced by 30–50% compared with autumn yields. Different technical options for establishment, harvesting and handling of miscanthus have been developed and these significantly effect production costs. Miscanthus production is characterized by low fertilizer and pesticide requirements making it a relatively benign crop environmentally. The main limitations to miscanthus production from M. x giganteus are the high establishment costs, poor over-wintering at some sites and insufficient water supply in southern regions of Europe. New agronomic techniques and new genotypes with improved characteristics are being developed and screened over the wide range of ecological conditions in Europe. Against this background of European experience the prospects for growing miscanthus in North America are discussed.

Introduction

Miscanthus is a perennial rhizomatous grass with the C₄ photosynthetic pathway. The genus Miscanthus has its origins in the tropics and subtropics, but different species are found throughout a wide climatic range in East Asia [1]. The remarkable adaptability of miscanthus to different environments [2] makes this novel crop suitable for establishment and distribution under a range of European and North American climatic conditions.

Miscanthus was first cultivated in Europe in the 1930s, when it was introduced from Japan. A number of ornamental varieties of miscanthus are known to exist under various common names. A sterile hybrid horticultural genotype, Miscanthus x giganteus¹ GREEF et DEU [1] was brought back to Denmark by Aksel Olsen in 1935, and was observed to have exceptionally vigorous growth [5]. Extensive field trials of M. x giganteus GREEF et DEU have been carried out in northern Europe since 1983, and have shown the capacity for high yields, over 20 t dry matter $\text{ha}{}^{\mathrm{-1}}\text{year}{}^{\mathrm{-1}}$ [6], [7] (Fig. 1). Based upon promising preliminary results, an international research project funded under the European JOULE program was initiated in 1989. Field trials were established in Denmark, Germany, Ireland and the UK to investigate the biomass potential of M. x giganteus across northern Europe. In 1993, a larger project was set up under the European AIR program, which extended the distribution of field trials into southern Europe, including Greece, Italy and Spain [8]. Nationally funded projects in Denmark, Netherlands, Germany, Austria and Switzerland supported research on propagation and establishment, management practices, harvest and handling of miscanthus.

These trials have shown both the potential of M. x giganteus in Europe, and its limitations. Key agronomic advantages are its high yields, and its low fertilizer and pesticide inputs. Tests have shown that M. x giganteus biomass can be used as solid fuel, in construction materials such as pressed particle-board, and as a source of cellulose. Key disadvantages include relatively high establishment costs, narrow genetic base, and low hardiness in the first winter following establishment of M. x giganteus.

The aim of this article is to review European research results and to describe the current options for miscanthus production. From the experience gained with miscanthus in Europe, conclusions can be drawn for transfer and application in other parts of the world, such as North America.