Tripsacum laxum Scrib and Merr.

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Graminae

Synonyms

Tripsacum fasciculatum Trin.

Common names

Guatemala grass, zacate prodigio (Latin America).

Note

It has recently been suggested that Tripsacum laxum should be renamed Tripsacum andersonii but as T. laxum is still common then both names are used here 

Description

Culms stout, up to 3 m tall and 2.5 cm thick at base. Leaf-blades broad (to 9 cm wide), sheaths glabrous. Racemes slender, several in a terminal group; one male spikelet of a pair sessile, one pedicelled. It differs from T. dactyloides in having a slender inflorescence, and the male spikelets are 4 mm long (Gilliland et al., 1971).

Distribution

Mexico and South America; now introduced to Sri Lanka and some other tropical countries, including Fiji.

Season of growth

Summer.

Rainfall requirements

Humid areas with rich soils, moist, but well drained.

Drought tolerance

It has poor tolerance to drought.

Soil requirements

It needs rich soil, but will tolerate acidity and aluminium. In Suriname, it does best on podzolic soils.

Sowing methods

Established by planting stem cuttings or rooted culms at the beginning of the rainy season, either in holes or in a plough furrow 50-65 cm apart in 1 m rows (about 10 000 per hectare; Risopoulos, 1966).

Vigour of growth and growth rhythm

Optimum production is reached six months after planting the cuttings, with four months between harvests.

Main attributes

Its high yield and persistence

Main deficiencies

Its poor seed production.

Chemical analysis and digestibility

This coarse tropical grass contains less than half as much digestible crude protein, and approximately three-quarters as much starch equivalent, as the fine grasses of the temperate zone. Harrison (1942) showed Guatemala grass cut at six weeks to contain 20 percent dry matter, 1.3 percent digestible crude protein and 7.9 percent starch equivalent.

Tolerance to flooding

It does not tolerate flooding.

Fertilizer requirements

Tripsacum removes 400 kg nitrogen, 80 kg phosphorus, 50 kg potassium, 50 kg calcium and 50 kg magnesium annually per hectare of soil, and so must be adequately fertilized (Risopoulos, 1966).

Seed production and harvesting

It does not flower readily, and seed production is unusual except in its native habitat.

Economics

A good fodder plant, and much used in Sri Lanka as a soil binder and organic-matter builder in upland tea estates (Bor, 1960; Andrew, 1971). It is also used as a fodder grass in Fiji, Suriname, Malaysia and Puerto Rico.
It is more persistent than elephant grass (Pennisetum purpureum) but less productive and of lower nutritive value.

Animal production

It is used by dairy farmers in Fiji as green chop-chop for zero grazing (Roberts, 1970a, b). On the podzolic soils of the Lelydrop landscape in Suriname, planted cuttings of T. laxum after three years' grazing at intervals of two months gave a live-weight increase of 300 kg/ha, with a live-weight gain of 278 g per head per day over ten months (Appelman & Dirven, 1972).
In Brazil, a mixed silage of 50 percent Tripsacum laxum, 30 percent Lablab niger and 20 percent Saccharum officinarum decreased milk yield by 10 percent, compared with maize silage; a T. laxum and S. officinarum silage reduced yield by 19 percent (Assis et al., 1962).

Further reading

Appelman & Dirven, 1972.

Suitability for silage

Andrew (1971) states that it is capable of very high production. It makes useful silage (Boudet, 1975; Medling, 1972; Assis et al., 1962). It lost 12 percent of its dry matter during ensilage (Paterson, 1945).