**4. Thai grasses**

There are many grasses already grown in Thailand that have the potential to be used as lignocellulosic feedstock for biofuel production. Several studies were suggested that wild grasses have lignocellulosic matter as new sustainable substitute raw materials for the establishment of biofuels. Many types and varieties of wild grasses are available in Thailand (**Table 1**). These grasses were potentially possible to use as a raw materials for biogas production.



a Banka et al. [14].

erable quantity of environment protection, owing to the capability of grass to sequester carbon into the soil matrix. Furthermore, various socioeconomic profits are possible to achieve without

Perennial grasses, especially C4 grasses, are excellent candidate feedstocks for renewable energy production in support of several rationales such as high potential of dry matter yields, fast growth, and additional potential use of inputs compared to annual crops [12]. Furthermore, perennial grasses offer highest biomass yield which can be available for many harvests per year and give vital role in ecosystem services, for example, carbon sequestration in roots and soil, and to contribute the reduction of soil erosion due to massive perennial root systems that stabilize the soil. Lignin content which is negatively correlated with sugar release is lower in perennial grasses (161–192 mg g−1) when compared to woody plants (157–279 mg g−1) [13].

In Thailand, most of dairy cattle are grown by small-scale farmers and the grasses are used for cattle feeding. In common practice, para (*Brachiaria mutica*), ruzi (*Brachiaria ruziziensis*), guinea (*Panicum maximum*), and Napier grass (*Pennisetum purpureum*) are used in cattle feeding. Much of the prior research on candidate perennial grass biomass crops in Thailand has focused on *Brachiaria ruziziensis, Cynodon* sp., *Digitaria decumbens, Miscanthus sinensis, Panicum maximum, Paspalum atratum, Pennisetum polystachyon, Pennisetum purpureum, Pennisetum purpureum* ×

There are many grasses already grown in Thailand that have the potential to be used as lignocellulosic feedstock for biofuel production. Several studies were suggested that wild grasses have lignocellulosic matter as new sustainable substitute raw materials for the establishment of biofuels. Many types and varieties of wild grasses are available in Thailand (**Table 1**). These grasses were potentially possible to use as a raw materials for biogas produc-

**Common name Scientific name Cultivation province Dry matter**

Miscanthus grass *Miscanthus sinensis* Chachoengsao N/Ab Mission grass *Pennisetum polystachyon* Nakhon Ratchasima N/Ab *Pennisetum polystachyon* Phitsanulok, Phichit,

Atratum grass *Paspalum atratum* Chiang Mai, Lampang,

*Pennisetum americanum* (pearl millet)

*Pennisetum purpureum* (Napier grass) × *Pennisetum americanum* (pearl millet)

Bana grass *Pennisetum purpureum* (Napier grass) ×

**yield (ton/ha/ year)a**

18.8

7.7

N/Ab

Ratchaburi, or Phetchaburi

Nakhon Ratchasima 49.1

Nakornsawan, Tak, Uttaradit, or

Sukhothai

Chiang Mai, Lampang, Ratchaburi, or Phetchaburi

harming the food industry [11].

156 Advances in Silage Production and Utilization

*Pennisetum americanum*, and *Vetiveria zizanioides*.

**4. Thai grasses**

tion.

b Information is not available in the literature.

**Table 1.** Types of grasses grown in Thailand.

*Brachiaria ruziziensis*: Ruzi grass *(B. ruziziensis)* used mainly for domestic animals grazing. Initially, ruzi grass was native to southern African continent. It came to Thailand in 1968 from Australia. Subsequently, the grass has become popular as cattle silage because of the large production of seeds, easy to grow nature, and status as a feedstock. There are few draw backs like sensitivity to the dry climate and requirement of fertilizers [15].

*Pennisetum purpureum* × *Pennisetum americanum*: Due to the success of both Napier grass (*P. purpureum*) and pearl millet (*Pennisetum americanum*) as potential lignocellulosic feedstocks, they have been bred to create hybrids, such as bana grass [23]. Bana grass was first produced in South Africa in the 1950s and is now widely grown throughout the tropical and subtropical areas of the world [24]. Bana grass's high yield, hardiness (even when grown in harsh conditions), and its ease of harvesting have made it one of the most popular hybrids [23].

Grass Silage for Biogas Production http://dx.doi.org/10.5772/64961 159

*Vetiveria zizanioides*: Generally, *V. zizanioides* called as vetiver grass. It is also perennial grass native to South Indian peninsula. It is used as a source of food and aromatic oils in worldwide. Furthermore, the grass has potential to apply in remediating contaminated soils, treating waste water, and reducing soil erosion [25]. Like Napier grass, vetiver grass has been examined already in Thailand as a potential source of lignocellulosic biomass for bioethanol conversion,

Soil fertility is generally rich in Thailand. Genus Pennisetum (including Napier grass) has been reported as the most productive tropical grasses in Thailand. Eight cultivars of Napier grass, namely Dwarf, Muaklek, Bana, Taiwan A148, Common, WrukWona, Tifton and Kamphaeng Saen, are grown in Thailand. There are several cultivars regularly grown from this genus for domestic animal feed. King Napier, Bana, WrukWona, Merkerson, and the short type (Mott dwarf) are called as common Napier. It can produce highest biomass yields more than 25 t/ha/ yr dry matter when cut at 30-day intervals. In central Thailand (at Pak Chong), biomass yield was achieved at 75 t/ha/yr when cut at 60-day intervals. The scales of biomass yields demon-

There is a huge awareness in the prospective utilization of Napier grass to produce ethanol in Thailand. Recently, these cultivars were selected for utilization as animal feeds, because of high leaf percentage, high nitrogen concentration, and low fiber levels. Because of its high dry matter yield, it was considered mainly as animal feed. On the contrary, for biofuels production, there is a need to get highest yield of biomass with suitability to be used either for direct combustion or for ethanol conversion. Therefore, the objectives of this paper were to quantify the yield and quality of biomass produced in different seasons by a range of Napier grass cultivars when cut at three monthly intervals throughout the year and to assess their potential as a source of

In general, Rengsirikul et al. [18] confirmed that tall cultivars reach a greater length (2–4 m) than Dwarf (<1 m) with Muaklek intermediate. Furthermore, annual biomass yield was differed significantly among cultivars (**Table 2**). The tall cultivars yielded 46.3–58.4 t/ha/yr compared with 27.1 and 35.1 t/ha/yr for Dwarf and Muaklek, respectively. **Table 2** indicates that the potential of tall Napier grass cultivars to produce high biomass in Thailand to satisfy the increasing need for energy. Napier grass is tropical forage; thus, these findings can be

partly due to its robustness and potential height of two meters [6, 25].

strated that Napier grass as a hopeful species for methane generation [18].

energy for biofuel production in central Thailand.

applicable to other countries in the tropical region as well.

**5. Napier grass**

*Cynodon sp*.: *Cynodon sp*. includes perennial grasses referred to as Bermuda grass or star grass, which are commonly grown in the topics and subtropics of the Americas, Africa, and South-East Asia [16]. Generally, they have been used for forage or as fodder for bioenergy [17]. Though Rengsirikul et al. [18] refer to Tifton grass as a type of Napier grass [18], Tifton grass is a specific breed of Bermuda grass (*Cynodon dactylon* L.) from Tifton, Georgia, USA, that was bred for its improved digestibility as a potential biofuel feedstock [17].

*Digitaria decumbens*: Pangola grass, scientific name *Digitaria decumbens* or *Digitaria eriantha*, is a forage grass originating from South Africa that is currently grown worldwide in the Americas, Africa, Oceania, Australia, and Asia [19]. It has been grown in Thailand since 1983 due to its success as fodder for grazing animals and its ability to grow on lands that previously cultivated rice [19].

*Miscanthus sinensis*: Miscanthus grass was generally called as Chinese silvergrass. Its scientific name is *Miscanthus sinensis*. Chinese silvergrass is native to eastern Asia, including Thailand. It is a perennial and clumping grass and also grown in some parts of the Americas and Europe. The grass can grow up to 2–3 meters tall [20]. Nowadays, this grass is used as cattle fodder and has been considered as a possible feedstock for biofuels.

*Panicum maximum*: Purple guinea grass, or *Panicum maximum* cv. Tanzania, is originally from the Ivory Coast of Africa. It is another perennial grass with a high protein content that is currently used as a feedstock for grazing animals in Thailand, having been introduced to the country in the 1980s [21].

*Paspalum atratum*: Atratum grass, known by its scientific name *Paspalum atratum*, is a perennial grass that can grow 1–2 meters tall. It originated in South America and is now cultivated in the Americas, South-East Asia, and Australia, generally near the equator. Though atratum grass has low drought tolerance, it is popularly grown in Thailand due to its ability to flourish during the rainy seasons and in wet soils [15].

*Pennisetum polystachyon*: Mission grass (*P. polystachyon*) is originally grown in tropical Africa. But for the past few decades, the grass has been spread throughout Africa, Asia, Australia, and Oceania. It can grow roughly 3 meters tall and is commonly known as a weed. The grass is a perennial and clumping grass. Mission grass is considered as an established weed that is currently not used for any specific purpose in Thailand [22].

*Pennisetum purpureum: Pennisetum purpureum* Schumacher, more often referred to as Napier grass or elephant grass, is a perennial grass native to Africa that has since been cultivated in tropical areas in Asia, Oceania, and the Americas. Napier grass is a hardy grass that can grow up in clumps up to seven meters in height and is particularly important as a forage and pasture grass, erosion inhibitor, mulch, and as a windbreak for other crops. Due to Napier grass's attractive qualities, such as good productivity, high yields, and drought tolerance, several types of Napier grass have already been investigated in Thailand for their potential in bioethanol conversion to bioethanol. The types of Napier grass which were already investigated include common, dwarf, Kamphaeng Saen, king, Muaklek, Taiwan, and WrukWona [6, 18].

*Pennisetum purpureum* × *Pennisetum americanum*: Due to the success of both Napier grass (*P. purpureum*) and pearl millet (*Pennisetum americanum*) as potential lignocellulosic feedstocks, they have been bred to create hybrids, such as bana grass [23]. Bana grass was first produced in South Africa in the 1950s and is now widely grown throughout the tropical and subtropical areas of the world [24]. Bana grass's high yield, hardiness (even when grown in harsh conditions), and its ease of harvesting have made it one of the most popular hybrids [23].

*Vetiveria zizanioides*: Generally, *V. zizanioides* called as vetiver grass. It is also perennial grass native to South Indian peninsula. It is used as a source of food and aromatic oils in worldwide. Furthermore, the grass has potential to apply in remediating contaminated soils, treating waste water, and reducing soil erosion [25]. Like Napier grass, vetiver grass has been examined already in Thailand as a potential source of lignocellulosic biomass for bioethanol conversion, partly due to its robustness and potential height of two meters [6, 25].
