(a) What is switchgrass?

Switchgrass (Panicum virgatum L.) is a perennial tropical grass (C4 species) native to the Great Plains of the USA. The indigenous people of the region saw and called prairies consisting of switchgrass “Ocean of grass”. The plant height is ca. 90-150 cm, the leaf blade length is 15-45 cm, the width is 0.6-1.3 cm, with

short rhizomes. Switchgrass exhibits adaptation to Fig. 2.7.1. Switchgrass Trial

relatively wet and fertile soils and is also tolerant of (USDA AR^ El Ren° OK UBA,

courtesy of Dr. B. Venuto)

both drought and flooding conditions. Annual dry matter yields are ca. 15 t/ha (Some data exhibit nearly 30 t/ha) and as with most forage species, its nutritious value lessens after the flowering. Seed yield is ca. 230 kg/ha from broadcasted stands and ca. 690 kg/ha from row-seeded stands. The 1,000-seed weight ranges 1.07-1.22 g.

(b) Advantages of switchgrass as a raw material for biofuel production

In the USA, Switchgrass has attracted the interest as a raw material for bioethanol production through cellulosic fermentation. The dry matter yield, however, is mostly similar to or less than some temperate and tropical forage grasses, it will not be very useful to use this grass for biofuel production in Japan. For example, if ca. 16t/ha of hay is harvested and 300 L of ethanol is produced from 1 t of hay, based on the price of raw materials, the cost of producing 1 gallon of ethanol from switchgrass is estimated at 0.51-0.89 USD, which is lower than the cost of 0.7-1.21 USD utilizing corn. This report suggests that the potential conversion of ca. 33 million ha of pasture, typically consisting of poorer soils and utilized for the production of a low quality hay crop for horses, to corn would lead to dramatic increases in soil erosion. If, however, switchgrass is sown to this area, ca. 520 million tons of hay can be produced and bypass the soil erosion problem caused by an annual corn crop. This point is very important for the USA, which maintains vast pasturelands and has a need to establish a cultivation system of perennial forage grasses, such as switchgrass, for biofuel production.

Once switchgrass pastures are established, a low-input, sustainable cultivation system for biofuel production may be practical. This system would be similar to the system in Japan that utilizes Miscanthus for a similar purpose. One deficit of the species is its seed dormancy. Seedlings germinate irradically and more than 1 year may be required to achieve a full stand.

(c) Cultivar of Switchgrass

Some cultivars developed in the USA are explained below.

(1) Alamo

Soil Conservation Service (SCS) and Texas Agriculture Experiment Station (AES) selected from collection in Texas, and released in 1978. It is a “lowland type”, flowers 1 or 2 month later than cv. Blackwell, taller, wider leaves with medium saline tolerance and high productivity. It grows well on all soil types with 630 mm or more annual precipitation, from Iowa to Florida.

(2) Blackwell

The SCS in Kansas developed this cultivar from single plant collected in Blackwell, OK and released it in 1944. It is an “upland type” of medium height with rather large stems, good in seedling vigor, high in forage production, and grows well on wide range of soil types with 500 mm or more annual precipitation in Kansas, Oklahoma, southern Nebraska and north Texas.

(3) Cave-In-The-Rock

The SCS and Missouri AES developed from the collections of Cave-in-the-Rock, IL and released in 1973. It is a “lowland type” with high seedling vigor, resistance to lodging and diseases. It is tolerant to flooding and drought and grows well in Iowa, Kansas, and Missouri.

(4) Dacotah

The SCS and Northern Great Plains Research Laboratory selected 10 plants from collections of North Dakota and released the cultivar in 1989. It flowers 27 days earlier than cv. Forestburg, 45 days earlier than cv. Blackwell and cv. Pathfinder. It is shorter in height and exhibits high drought tolerance. It grows well in North Dakota, Minnesota, and Montana.

(5) Forestburg

The SCS in North Dakota and Northern Great Plains Research Laboratory developed this cultivar from collections obtained near Forestburg, ND and released in 1987. It has superior winter hardiness and persistence, seed production ability, and is of earlier maturity than other cultivars. Forage production at northern latitude exceeds that of cv. Dacotha, cv. Nebraska 28. It grows well in Montana, North and South Dakota, and Minnesota.

(6) Kanlow

The Kansas AES developed this cultivar from collections in Oklahoma and released in 1963. It is a tall and productive “lowland type”, especially adapt to lowlands where excess water problems occur; it also performs well on upland sites where soils are not too thin or dry.

(7) Pathfinder

The Nebraska AES originally released this cultivar as “Type-F” from a polycross and progeny test of collections in 1967. It is a late-flowering “highland type”, winter-hardy, vigorous, leafy, and resistant to rust and drought. It grows well in Nebraska and adjacent areas.

(8) Shelter

The SCS in New York developed this cultivar from collections made in West Virginia and it was released 1986. The cultivar exhibits thicker stems and fewer leaves than the other cultivars with the exception of cv. Kanlow. It is taller and flowers earlier by 7-10 days than cv. Blackwell but exhibits less seedling vigor during the 1st year of establishment. It grows well in a wide region ranging from the East Coast to Arkansas in the central USA.

(9) Trail Blazer

Nebraska AES developed this cultivar from collections made in Nebraska and Kansas and released in 1984. It is a “highland type” exhibiting both higher forage value and yield, flowers

at the same time of cv. Blackwell. It grows well in central Great Plains and eastern states. Additional released cultivars not described are: cv. Sunburst, cv. Caddo, cv. Summer etc.

Further information

Long, S. P. et al. (eds.): Primary productivity of grass ecosystems of the biosphere, 1-267,Chapman & Hall (1992)

Nakagawa, H.: Development and cultivation of forage grasses and crops for clean bio-methanol production to keep gobal environment, Farming Japan Vol. 35-2:22-31(2001)

Nakagawa H. and Momonoki T.: Yield and persistence of guineagrass and rhodesgrass cultivars on subtropical Ishigaki Island, Grassland Science, Vol. 46, pp. 234-241 (2000)

Sakai, M., and Nakagawa H.: A new biofuel towards 21st century, The Chemical Daily Co. Ltd., (in Japanese), pp. 1-197

Burnhart, S., Management guide for the production of switchgrass for biomass fuel in Southern Iowa, http://www. extension. iastate. edu/Publications/PM1710.pdf, (2003)

Nakagawa, H., Forage crops in tropics, Association for International Cooperation of Agriculture and Forestry, Tokyo (in Japanese) (1998)

United States Department of Agriculture, Grass varieties in the United States, CRC Press, Boca Raton. (1995)

Vogel, P. K., Energy production from forages (or American Agriculture — back to the future), Journal of Soil and Water Conservation, Vol. 51, No. 2, 137-139. (1996)