*5.2.3. Ecological demands*

Switchgrass will grow best on well-drained good quality soils but will also sustain lower quality soils and shallow rocky soils. It can grow on sand to clay loam soils and tolerates soils with pH values ranging from 4.9 to 7.6 [63]. It is drought tolerant, but the grass does not grow in locations where precipitation is below 300 mm per year. Switchgrass can tolerate shortterm waterlogging.

Switchgrass can be categorized into two groups or ecotypes classified by their habitat preference: the upland ecotype and the lowland ecotype. Upland ecotypes occur in upland areas that are not subject to flooding, while lowland ecotypes are found on floodplains and other areas that receive run-on water.

The upland ecotype is generally thinner stemmed and shorter than lowland ecotypes, is adapted to drier and wetter environments, and is generally derived from accessions collected in the northern regions of North America. Lowland plants have a later heading date and are taller with larger and thicker stems. Lowland ecotypes are tetraploids, while upland ecotypes are either octoploids or tetraploids. There are ecotypical differences among switchgrass ecotypes for important compositional features, such as fiber, nitrogen, and ash, among others. Dry matter produced by lowland ecotypes has higher cellulose and hemicellulose contents and lower N and ash contents than upland ecotypes, and dry matter produced by upland ecotypes contains higher lignin contents [64]. Upland and lowland tetraploids have been crossed to produce F1 hybrids that have an increase in yield of 30–50% over the parental lines. These hybrids are promising sources of high yield biomass cultivars [64]. Most seedlings of switchgrass will germinate after 3 days at 29.5°C. However, they germinate very slowly when the soil temperature is below 15.5°C [63].

#### *5.2.4. Biomass yields and characteristics*

The highest biomass yields per hectare can be obtained when switchgrass is harvested once or twice per year. In fact, one- or two-cut systems often provide similar average yields [65]. Wullschleger et al. [66] compiled 1190 biomass yield observations for both lowland and upland types of switchgrass grown on 39 sites across the USA, from field trials in 17 states, from Texas to North Dakota to Pennsylvania. In this study, it was found that much of the differences in biomass yields could be explained by the variation in the growing season, precipitation, annual temperature, nitrogen fertilization, and the type of switchgrass grown in a specific region. Annual yields averaged 12.9 t DM ha−1 for lowland and 8.7 t DM ha−1 for upland ecotypes. Some field sites in Texas, Oklahoma, and Alabama reported biomass yields greater than 28 t DM ha−1 using the lowland cultivars "Kanlow" and "Alamo."

Generally, a single harvest during the growing season maximizes biomass recovery, but harvest after a killing frost will ensure stand productivity and persistence, particularly when drought conditions occur, and reduce requirements of nitrogen fertilizers. Delaying the harvest until spring will reduce moisture and ash contents of the biomass; however, the yield loss can be as high as 40% compared to an autumn harvest [73]. With proper management, productive stands can be maintained for more than 10 years. It is not recommended to harvest

Bioenergy from Perennial Grasses

11

http://dx.doi.org/10.5772/intechopen.74014

Reed canarygrass (*Phalaris arundinacea* L.) is a member of the Poaceae family. It is a coolseason grass that is less productive than warm-season grasses. It is a sod-forming, perennial wetland grass, native to the temperate regions of Europe, Asia, and North America. It is usu-

Reed canarygrass is a tall, coarse, and erect grass with a C3 photosynthetic pathway, which reaches a canopy height of up to 300 cm. This grass has vigorous rhizomes that form 1 cm

Its inflorescence is a narrow and compressed panicle. The leaves are wide and flat with prominent nodes. The stems are robust, smooth, and occasionally branching at the nodes. Its ligules are membrane-shaped and obtuse and have a pointed-folded tip. Seeds are shiny brown. The seed production of the species is unreliable due to the seed shattering and occasionally the production of deficient panicles [11]. The presence of several types and concentrations of poisonous alkaloids has restricted the use of reed canarygrass as a forage crop [75]. The esti-

Reed canarygrass is a persistent species, which grows well on most types of soils, except droughty sands. It is one of the best grass species for poorly drained soils and tolerates floods better than other cold-season grasses. However, the highest yield can be obtained on organic soils. Reed canarygrass is adapted to and grows very well in a cool temperate climate and has also good winter hardiness. In order to induce flowering, this grass requires exposure to short days (primary induction) followed by long days for initiation of floral primordial and

There are considerable differences in yield between different soils. Kukk et al. [77] reported that soils with low N content produce yields of almost 1 t DM ha−1 in years with unsuitable weather conditions for plant growth. On the other hand, it is possible to achieve an average

thick and short branches and a root system that reaches to more than 3 m [74].

mated life time of a reed canarygrass plantation is approximately 10 years [76].

inflorescence development (secondary induction) [77].

*5.3.4. Biomass yields and characteristics*

switchgrass in summer or after flowering when there are drought conditions.

ally found in wet areas such as lake shores and along the rivers.

**5.3. Reed canarygrass**

*5.3.1. Origin and distribution*

*5.3.2. General species description*

*5.3.3. Ecological demands*

The main characteristics of switchgrass biomass are listed in **Table 1**. Sladden et al. [67] compared eight switchgrass genotypes that were cut at the same maturity and found the six upland types did not vary much in their biomass composition. However, "Alamo" and "Kanlow" showed significantly lower N contents and higher fiber contents in their biomass which is explained by the later harvest date at maturity instead of differences in nutrient partitioning.

#### *5.2.5. Switchgrass as a bioenergy crop*

Switchgrass is established mainly by seeding. Successful stand establishment during the seeding year is essential for economically viable switchgrass as a bioenergy crop [68]. Stand failure as a result of poor seed quality or seedling physiology will have important implications on the cost of switchgrass biomass. However, weed competition is the major reason for switchgrass stand failure. Acceptable switchgrass production can be delayed by one or more years due to poor weed management and deficient stand establishment [69]. Switchgrass is readily established when high-quality seed of an adapted cultivar is used with the appropriate planting date, seeding rate, seeding method, and proper weed control. Switchgrass can be drilled in a conventional seedbed or by direct seeding methods. According to Sladden et al. [67], a row spacing of 80 cm is recommended because this led to higher yields in the second and third years than row spacing of 20 cm. Before planting, soil tests are recommended. N fertilizer is not recommended during the planting year since it will promote weed growth, increase competition for establishing seedlings, and increase economic risk and cost associated with establishment if stands should fail [70]. Economically viable yields will require N fertilization rates between 50 and 100 kg ha−1 yr.−1 [71]. N fertilizer should be given in late spring. P and K can be applied before seeding to promote root growth and encourage rapid establishment. Switchgrass can tolerate moderately acid soils, but optimum germination of the seed occurs when the soil pH is between 6 and 8 [72].

Weeds can be an important obstacle for switchgrass establishment, especially summer annuals. Spraying herbicides to control broadleaf weeds is usually needed only once or twice every 10 years in established and well-managed switchgrass stands. One year before planting, the field must be plowed or chiseled [63]. A reduction of weed competition can also be achieved by cutting infrequently at 10 cm. In order to control grasshoppers, crickets, and other insects which may affect the new seedlings of switchgrass an insecticide may be needed [63].

Generally, a single harvest during the growing season maximizes biomass recovery, but harvest after a killing frost will ensure stand productivity and persistence, particularly when drought conditions occur, and reduce requirements of nitrogen fertilizers. Delaying the harvest until spring will reduce moisture and ash contents of the biomass; however, the yield loss can be as high as 40% compared to an autumn harvest [73]. With proper management, productive stands can be maintained for more than 10 years. It is not recommended to harvest switchgrass in summer or after flowering when there are drought conditions.
