5. Cultural Practices Employed

The miscanthus crop is established by planting mechanically divided rhizomes or plantlets micropropagated in tissue culture. Mechanically divided rhizome pieces may be collected with a potato or flower bulb harvester from nursery fields (preferably with sandy soils for ease of tilling), planted at a density of 3-6 plants/m². After 2-3 years, nursery fields are subjected to a single pass of a rotary tiller, breaking up rhizomes into 40- to 100-gram pieces (Fig. 3). This yields a multiplication factor of about 50 ×, in comparison with 100 × for hand cutting of rhizomes from whole plants (Pari 1996; Huisman et al. 1996). Disc harrowing of rhizomes followed by collection of pieces with an automated stone picker has also been used, yielding lower multiplication rates (Wilkins and Redstone 1996). Micropropagation offers potentially much higher multiplication rates (up to 2000 ×; Lewandowski and Kahnt 1993), but these techniques are currently considerably more expensive than mechanical rhizome division.

Larger rhizome pieces, covering with straw or cover crops, and deeper planting all increase overwinter survival and establishment rates, but new cultivars and genotypes (e.g. M. sinensis "Goliath" have superior survival rates to M. x giganteus (Eppel-Hotz et al. 1998). Similar results were obtained by Schwarz et al. (1998), who also found that micropropagated plantlets were more sensitive to suboptimal conditions (e.g., summer drought). In general, irrigation of newly planted rhizomes appears to improve establishment rates under drier conditions. Mechanization of rhizome establishment has reduced costs to ECU 350/ha (US$ 410/ha), and ECU 200/ha (US$235/ha) may be expected in the future. Earlier cost estimates were ECU 0.04/rhizome (US$0.047/rhizome), or ECU 400/ha (US$470/ha) at 10,000/ha (Huisman et al. 1996).

At a typical planting density of 10,000 plants/ha (1-meter spacing), a dense root mat has developed by year 2 or 3, which can prevent leaching of nitrogen. By this time the maximum root density is found at a depth of 0-40 cm, although some roots penetrate down to 250 cm (Koessler and Claupein 1998).

To harvest the miscanthus crop, a chopping forage harvester may be used (Kemper Champion 3000), although a row-independent device is needed on older stands where the original planting pattern has become indistinct (Fig. 4). Such harvesting trials have used a chopped length from 11 mm to 44 mm. Baling and bundling are both possible (Fig. 5), but field losses (10% or more due to baling) and stem size/stiffness (bundling) need to be taken into account (Huisman et al. 1996; Venturi and Huisman 1997).