Axonopus compressus (Swartz) Beauv.

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Graminae

Common names

Broad-leaf carpet grass (Australia), savannah grass (West Indies), nudillo (Peru), bes-chaitgras (Suriname), caamazo (Cuba).


Description

A. compressus is similar to A. affinis in most of its botanical characters but it is more robust and stoloniferous. It has stouter culms and stolons, wider leaves and longer spikelets which are more acute. Its leaves are 9-12 mm wide and it forms a dense mat over the surface of the ground, seldom reaching a height of more than 15 cm. The spikelets are 2.2-2.5 mm compared with 2 mm for A. affinis. There is a more pronounced tuft of hairs at the apex of the lemma than in A. affinis (Barnard, 1969). There is a good deal of variation in size and stolon and rhizome formation with environment and management

Distribution

Native to the southern United States, Mexico and Brazil. Now introduced into most tropical and subtropical countries, especially west tropical Africa, South Africa, India, the Philippines, Indonesia, Australia and the Pacific islands.

Season of growth

A summer-growing perennial very similar in needs to A. affinis.

Rainfall requirements

Higher than for A. affinis, with about 775 mm minimum. In Trinidad it needs 40 cm of rain between January and May (Gumbs & Shastry, 1978).

Drought tolerance

Less tolerant of dry conditions than A. affinis.

Soil requirements

It prefers moist sandy soil throughout the year, a little more moisture than required for A. affinis, and it also has a lower soil fertility requirement than Paspalum dilatatum, but will respond to moderate fertilizer treatment.

Ability to spread naturally

It spreads more quickly by stolons and rhizomes under favourable conditions than A. affinis. It also spreads by seed, but does not produce such abundance of seed as A. affinis.

Land preparation for establishment

For a pure grass stand prepare a fine, weed-free seed-bed.

Sowing methods

It can be surface sown through a drill or broadcast.

Sowing depth and cover

Sow on the surface and roll after planting.

Sowing time and rate

Sow at 6 kg/ha in early to late summer.

Number of seeds per kg.

2 970 000.

Tolerance to herbicides

It can be controlled by similar treatments to A. affinis (Tilley, 1977).

Seedling vigour

Excellent.

Response to defoliation

Carpet grass stands a good deal of defoliation and in lawns has to be mown frequently.

Grazing management

Heavy grazing to maintain the grass in a vegetative condition is essential.

Response to fire

It will survive a fire but, owing to its habitat, fires are infrequent.

Suitability for hay and silage

It rarely provides enough material for conservation, and the stems are coarse.

Value as a standover or deferred feed

Very poor once it has seeded its nutritive value is very low.

Seed harvesting methods

The seed can be easily harvested with a stripper type harvester.

Main attributes

It grows quickly and stabilizes erosive soils in the higher rainfall tropics.

Main deficiencies

Its tendency to invade better pastures, its low quality after seeding, and the frequency of cutting needed in lawns.

Frost tolerance

Not so tolerant of frost as A. affinis.

Latitudinal limits

About 27N and S.

Response to light

It grows well in the shade. In Malaysia the yield of carpet grass under the leguminous rain tree Pithecolobium saman was 20 percent higher and the protein level 14 percent of the dry matter and 11 percent under non-leguminous shade (Jagoe, 1949).

Ability to compete with weeds

It will compete with weeds under favourable conditions.

Maximum germination and quality required for sale

60 percent (Queensland) germinable seeds, germinated at 20-35C moistened with KNO3.

Palatability

It is fairly palatable.

Chemical analysis and digestibility

The forage quality of broad-leaf carpet grass is poor, but higher than for A. affinis. Harrison (1942) recorded the dry-matter content of carpet grass (no stage mentioned) as 39 percent, the digestible crude protein at 1.8 percent, and the starch equivalent as 21.8 percent. Ghl (1975) has listed percent digestibility of six-week-old, 20-cm-tall growth.

Natural habitat

Subhumid and humid woodland and savannah, flourishing in moist soils.

Tolerance to flooding

It is not tolerant of swampy conditions.

Fertilizer requirements

CSIRO workers (Weier, 1976) have shown that A. compressus has an active nitrogenase system and over a 12-week summer growing period fixed 13 kg N/ha per day. A complete fertilizer is applied unless soil tests indicate otherwise.

Compatibility with other grasses and legumes

It will gradually invade Cynodon dactylon in lawns and will grow in association with white clover (Trifolium repens) and Desmodium triflorum.

Genetics and reproduction

2n=40, SO, 60 (Fedorov, 1974).

Economics

Used widely as a lawn grass in the tropics and subtropics, it invades as a low-quality pasture grass in these areas.

Animal production

In So Paulo, Brazil, zebu steers gained an average daily liveweight of 0.175 kg over 672 days which included two dry seasons (Rocha et al., 1962). In Fiji it is considered a useful feed, especially if sensitive plant (Mimosa pudica) is growing with it (Parham, 1955).

Further reading

Barnard, 1969; Gledhill, 1965; McLennan, 1936.

Value for erosion control

Good for stabilizing slopes against erosion where conditions suit it, and also for stabilizing banks of dams.