*5.2.2. General species description*

for the fact that the same clone has almost always been used in most studies or for cultivation. The sterility of *M. giganteus* is particularly interesting because it prevents the risk of invasion of the species; but on the other hand, it is a limitation to improve biomass production and to adapt it to a wide range of climatic conditions [47]. The sterile hybrid *M. giganteus* has to be propagated asexually using plantlets produced in tissue culture (micropropagation) or by rhizome divisions (macropropagation). The optimal planting density is one to two plants per square meter [11]. It has been reported that irrigation during the first growing season signifi-

Miscanthus does not respond to N fertilization at several sites in Europe; therefore, N fertilization is necessary only on soils with low N contents. Weed control in miscanthus in the year of planting is crucial for establishing a successful and healthy stand. The first 2 years are most critical, with little weed management thereafter. There are very few labeled herbicides for use on miscanthus crop, but various herbicides suitable for use in maize or other cereals can be used. It can be harvested only once a year, and the harvest window depends on the local conditions. The later the harvest can be made, the better the quality of the combustion, since it

However, there is a trade-off between improving the quality and yield, since yield losses of up to 35% can occur between maximum yield and late harvest in early spring [54]. From an economic point of view, a late harvest with biomass water content lower than 30% is recommended in order to reduce the costs for harvesting and drying of the biomass [55]. Bilandzija et al. [1] state that harvest delays, from autumn to spring, had statistically significant influence on moisture, C, H, O, N, and S contents. They found that delayed harvest enhanced the quality of biomass in terms of combustion process, primarily through lowering moisture content, which is particularly important if biomass producers do not have

Given its potential to be exploited for energy purpose, *Miscanthus × giganteus* is presently used mostly for electricity or heat generation in direct combustion [56], mostly in the form of wood chips, pellets/briquettes, and bales [57]. It is estimated that replacing fossil fuels with biomass

because there is presently only one commercially available clone, *Miscanthus × giganteus*, it has some limitations such as a lack of winter hardiness during the establishment period [7] and it

Switchgrass (*Panicum virgatum* L.) belongs to the Gramineae family. It is native to the North American tall grass prairies. Although generally associated with the natural vegetation of Great Plains and the western Corn Belt, it occurs widely in grasslands and nonforested areas throughout North America east of the Rocky Mountains and from southern Canada down to

needs to be propagated vegetatively resulting in high field plantation costs.

emission by 75–93% [48]. However,

will decrease the moisture content and the mineral content of the biomass.

from *Miscanthus × giganteus* can enable reducing the CO2

cantly improves the establishment rates.

8 Advances in Biofuels and Bioenergy

drying systems.

**5.2. Switchgrass**

*5.2.1. Origin and distribution*

Mexico and Central America [58].

Switchgrass is one of the best herbaceous energy crops due to its habit of perennial growth, high yield potential on a wide variety of soil conditions, and compatibility with conventional agricultural practices [59]. Switchgrass has a deep rooting system that contributes to the accumulation of organic matter in the soil and, therefore, carbon sequestration [60]. In full development of the plant, the underground biomass is similar or even greater than the aerial biomass.

Switchgrass can be established through seeds; therefore, it has lower production costs that make it a practical option among the energy crops. However, the switchgrass biomass yield is considered to be lower than that of miscanthus [11].

Switchgrass can grow to more than 3 m height and develop roots to a depth of more than 3.5 m. The inflorescence is a typical open and diffuse panicle of 15–55 cm long. Each panicle consists of many to hundreds of spikelets at the end of long branches, with two dissimilar florets in each spikelet [61]. The expected life of a pasture would be 10 years or more if properly managed. Switchgrass is a cross-pollinated plant that is largely self-incompatible, and most cultivars are tetraploid or hexaploid [62].
