Pennisetum purpureum Schumach.

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Graminae

Common names

Elephant or elefante grass, Napier grass, gigante (Costa Rica), mfufu (Africa).

Description

A robust perennial with a vigorous root system, sometimes stoloniferous with a creeping rhizome. Culms usually 180-360 cm high, branched upwards. Leaf-sheaths glabrous or with tubercle-based hairs; leaf-blades 20-40 mm wide, margins thickened and shiny. Inflorescence a bristly false spike up to 30 cm long, dense, usually yellow-brown in colour, more rarely purplish (Chippendall, 1955).

Distribution

Native to subtropical Africa (Zimbabwe) and now introduced into most tropical and subtropical countries.

Season of growth

Summer.

Altitude range

Sea-level to 2 000 m.

Rainfall requirements

Elephant grass grows best in high-rainfall areas (in excess of 1 500 mm per year), but its deep root system allows it to survive in dry times. Mean, 1 483 mm + 620 (Russell & Webb, 1976).

Drought tolerance

It survives drought quite well when established because of its deep root system.

Soil requirements

It grows best in deep, fertile soils through which its roots can forage. Deep, friable loams are preferable.

Ability to spread naturally

It is usually planted, as it spreads slowly.

Land preparation for establishment

Full land preparation with ploughing and subsequent disc-harrowing and drilling will repay the cost of establishment of this perennial grass.

Sowing methods

Either root cuttings or stem pieces with at least three nodes are planted in the drills. When planting stem pieces, two nodes should be covered with soil, the third being exposed. One hectare of grass will provide propagating material for 15-25 hectares. Planting rooted elephant grass pieces directly into an Imperata sward during the rainy season in the Philippines has had some success (Farinas, 1970).

Sowing depth and cover

Plant in furrows about 15 cm deep and cover with about 7.5 cm of soil initially, gradually filling as the plant grows.

Sowing time and rate

At the beginning of the wet season, at about 2 000 kg/ha of stem material.

Number of seeds per kg.

3 084 400 in the United States.

Tolerance to herbicides

To eradicate elephant grass, it should be burned off and any regrowth sprayed with 2,2-DPA at 4.5 kg of a 740 g AI/kg product (e.g. Shirpon, Dowpon) plus 250 ml wetting agent per 200 litres of water. Thoroughly wet the plants (Tilley, 1977).

Vigour of growth and growth rhythm

It is a very vigorous grass.

Response to defoliation

Elephant grass will stand heavy grazing and provides a great bulk of feed (Harrison & Snook, 1971), especially if fertilized and irrigated. It is suited to rapid rotational grazing, which must not be severe enough to hinder regrowth (Ware-Austin, 1963). Only the leaves are eaten when the grass is near maturity. A height of 5 cm is best for cutting (Vicente-Chandler et al., 1974).

Grazing management

Elephant grass is commonly used in a cut-and-carry system, feeding it in stalls, or it is made into silage. For grazing, it should be heavily stocked to maintain it in a lush vegetative form. The mature leaves are razor sharp and sometimes provide a problem for grazing cattle. The coarse stems produce new shoots and leaves called "lala" in Hawaii; the grass is best grazed when the new growth consists of five new leaves and associated stem growth. A stem plus "lala" takes a year to grow (Younge & Ripperton, 1960). Odhiambo (1974) showed no drop in nutritive value at Kitale, Kenya, in analyses taken at seven to 12 weeks. Grazing at six- to nine-week intervals at a height of about 90 cm gives good utilization. Nitrogen can be applied after each grazing or cutting in high-rainfall areas. Any coarse, leafless stems should be mowed.

Response to fire

Elephant grass will burn if dry enough, and produce new growth afterwards, but it is seldom dry enough to burn in its normal environment.

Dry-matter and green-matter yields

Elephant grass gives heavy yields and Vicente- Chandler, Silva and Figarella (1959) established a world record production of 84 800 kg DM/year when it was fertilized with 897 kg N/ha per year and cut every 90 days under natural rainfall of some 2 000 mm per year. Other recorded yields are 35 500 kg DM/ha per year over three years in Tobago (Walmsley, Sargeant & Dookeran, 1978), 32 400 kg DM and 3 400 kg crude protein per hectare per year when cut every 56 days at CIAT, Colombia (Moore & Bushman, 1978), 20 800 kg DM/ha per year in Nigeria (Adegbola, 1964) and 40 000-50 000 kg green matter per hectare when cut each 35-40 days at the Tulio Ospina Station, Colombia (Crowder, Chaverra & Lotero, 1970).ir

Suitability for hay and silage

It makes good hay if cut when young but is too coarse if cut late in its annual growth cycle. It is more usually made into silage of high quality without additives. Silage losses have been 9 percent in India (Mahadevan & Venkatakrishnan, 1957) and 17 percent in Puerto Rico (Vicente- Chandler et al., 1953). In Taiwan, elephant grass is widely used for the production of dehydrated grass pellets used as a supplementary stock feed (Manidool, personal communication).

Value as a standover or deferred feed

If the grass is allowed to reach maturity before the last wet-season cut, it gives better dry-season use. On the Atherton Tableland, Queensland, it is used for dry-season feed by rolling at the end of winter, as it can make some winter growth during this period (Quinlan & Edgley, 1975).

Toxicity

García-Rivera and Morris (1955) recorded 2.48 percent of oxalates in the dry matter of elephant grass and 2.5 percent in the Merker variety but no toxicity was experienced. Ndyanabo (1974) recorded 3.1 percent total oxalates but again no toxicity.

Cultivars

  • Var. merkeri (Merker grass) 

similar to common elephant grass but has finer leaves and stems. It is cultivated widely in Puerto Rico and other West Indian areas. It is more drought resistant than common elephant grass but less productive and of lower feeding value (Whyte, Moir & Cooper, 1959). It is resistant to Helminthosporium sp. in Puerto Rico (Vicente-Chandler et al., 1953).

  • 'Capricorn 

'developed at Biloela Research Station, Queensland, for high rainfall areas receiving up to 2 500 mm/year. It is leafier, more palatable and later- flowering than the common type.

  • 'Pusa Giant Napier' 

performs well in Sri Lanka under good soil conditions, but is affected by Helminthosporium sp. (Pathirana & Siriwardene, 1973).

  • 'Merkiron' and 'Costa Rica 532' 

are used in Colombia, and 'French Cameroons', 'Gold-Coast' and 'Cameroons' in Africa. 'Chad)' is recommended by Prasad and Singh (1973) for cultivation under arid conditions in West Rajasthan, India.

Diseases

The most common disease is blight caused by Helminthosporium sacchari. The best practice is to use a resistant variety.

Main attributes

Its high dry-matter yield, especially with frequent cutting under fertilization and irrigation. Its suitability for silage and its deep and extensive root system which enables it to forage widely for moisture and nitrogen.

Main deficiencies

Its high fibre content at maturity, poor seed production, and susceptibility to frosts.

Optimum temperature for growth

Usually 25-40°C. Mean 21.1° + 2.8°C (Russell & Webb, 1976).#S

Minimum temperature for growth

About 15°C. Mean minimum temperature of the coldest month 11.5° + 5.4°C (Russell & Webb, 1976). ye

Frost tolerance

It is susceptible to frosts.

Latitudinal limits

Usually between 10°N and 20°S (Russell & Webb, 1976).lp

Response to light

It will grow in partial shade as a cut-and-carry fodder in tropical gardens, but produces better in full sunlight.

Ability to compete with weeds

When established, elephant grass will suppress weeds.

Pests

No major pests have been recorded.

Palatability

It is highly palatable in the leafy stage.

Response to photoperiod

It is a short-day plant.

Chemical analysis and digestibility

Göhl (1975) gives a list of chemical analyses and digestibilities from a wide range of conditions.

Natural habitat

Damp grassland and forest edges, cultivation.

Tolerance to flooding

It does not tolerate flooding.

Fertilizer requirements

A complete fertilizer mixture may be needed for establishment according to soil fertility. In Tobago, West Indies, a crop of elephant grass removed 463 kg nitrogen, 96 kg phosphorus and 594 kg potassium per hectare per year. The optimum phosphorus content of the dry matter for growth was determined as 0.248 percent for the purple type and 0.215 percent for the green variety (Falade, 1975). High rates of nitrogen generally give good responses (Walmsley, Sargeant & Dookeran, 1978) especially in the third and subsequent years when the native soil nitrogen has been exhausted (Vicente-Chandler et al., 1953). The latter authors suggested that the highest yields could be expected from cutting at 12-week intervals and applying nitrogen after every cut.

Compatibility with other grasses and legumes

It is generally grown as a pure pasture. However, it has been sown in alternate rows with such legumes as Pueraria phaseoloides in Puerto Rico, Centrosema pubescens (Venezuela) and Neonotonia wightii in Uganda. Cutting or grazing management will have to be adjusted to favour the legume to maintain a satisfactory mixed sward.

Genetics and reproduction

The somatic chromosome number is 2n=27, 28, 56 (Fedorov, 1974). It crosses readily with Pennisetum americanum (P. typhoides) to produce a rugged hybrid, bane grass, used for wind-breaks in vegetable areas in coastal Queensland.

Seed production and harvesting

Elephant grass does not produce much seed, and so is propagated vegetatively.

Economics

It is one of the most valuable forage, soilage and silage crops in the wet tropics.

Animal production

At the National Research Station, Kitale, Kenya, elephant grass was fertilized at the rate of 80-120 kg triple superphosphate per hectare and 120 kg sulphate of ammonia per hectare. It supplemented sown pastures during their decline in growth in April, May and June when the dairy cows were calving. The elephant grass yielded 11 480 kg DM/ha in the second season and 4 360 kg DM/ha in the third season, carrying 2.5 and 2.4 beasts per hectare, respectively (Ware-Austin, 1963). In Hawaii, elephant grass can produce as much as 336 000 kg of green forage per hectare per year (Takahashi, Moomaw and Ripperton, 1966) and live-weight gains as high as 549 kg/ha were obtained with beef cattle grazing mature elephant grass. In Colombia, 36 milking cows were maintained on forage from 2.5 hectares of elephant grass. They received a nutritional supplement concentrate ratio of 1 kg per 4 kg milk and averaged 15 litres of milk per day (Crowder, Chaverra & Lotero, 1970). At CIAT, Colombia, Moore and Bushman (1978) calculated that 1 hectare of high-quality elephant grass would provide enough forage to produce 3 tonnes live-weight gain in zebu-type cattle.

Value for erosion control

Elephant grass will give very effective control of erosion in its own ecological niche.

Tolerance to salinity

No record of salinity tolerance has been found.

Links:

Links for the genus:

Further reading

Ware-Austin, 1963; Vicente-Chandler et al., 1974.