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Graminae
Synonyms
Amphilophis insculpta (A. Rich.) Stapf.
Common names
Sweet pitted grass (East Africa), pinhole grass (Zimbabwe and
South Africa), stippel grass (South Africa), creeping blue grass (Australia).
Description
A stoloniferous perennial, 30-100 cm high. Sessile spikelets
shiny, shallowly grooved below the pit and glabrous, rarely with the margins
finely hairy, pedicelled spikelets with three pits, rarely with one (Napper,
1965). It resembles Bothriochloa bladhii and B. ewartiana all three
have scented leaves and the scent persists in the hay. Creeping blue grass
can be distinguished by its conspicuously hairy nodes, the reddish-purple
colouring of the exposed stem portions and the development of creeping,
as well as upright, stems. It differs from Dichanthium aristatum and D.
annulatum in being scented, and having a pit on one side of the seed hull,
and from D. aristatum in also having no hairs at the base of the branches
(Bisset & Graham, 1978). Leaves, stems and seed-heads are aromatic
and the aroma persists in stored hay.
Distribution
Kenya, Uganda, Zaire, southern and north-eastern tropical Africa.
Common in Madras, the Nilgiris and Pulneys in India. Introduced to Australia
as CPI 2695 in 1931 as Amphilopis (syn. Bothriochloa) glabra (Bisset, 1978).
Season of growth
Summer.
Altitude range
Sea-level to 2 000 m.
Rainfall requirements
The lower yearly rainfall limit is about 500 mm and its range
generally 500-800 mm.
Drought tolerance
It is drought tolerant.
Soil requirements
It does very well on black clay soils but also on loams and
clay loams, and will vegetate on eroded clays, scalded areas and puggy
soils.
Ability to spread naturally
It spreads gradually in one case 1 m on each side of
a planted row in two years (Bisset & Graham, 1978).P
Land preparation for establishment
Establish on a well-prepared seed-bed, or in the ashes of a
burn. Oversowing may give reasonable results.
Sowing methods
Surface sow and lightly roll or harrow; broadcast on to a scrub
burn; broadcasting into barley stubble and brigalow is effective. In aerial
sowing push the seed out of the hopper by hand (Bisset & Graham, 1978).
Sowing depth and cover
Not deeper than 1 cm.
Sowing time and rate
Sow from November to January (summer) at 2 kg/ha. For soil
conservation sow at 9 kg/ha.
Number of seeds per kg.
About 1 210 000 fertile spikelets with one seed in each.
Seed treatment before
planting
A treatment to remove awns from the seeds would assist sowing.
A "de-awner" used for Stylosanthes humilis is successful with B. insculpta
seed.
Seedling vigour
Good.
Vigour of growth and growth
rhythm
A summer-growing perennial, it continues to grow into winter
until cut by frost, but is slow in coming away in the spring in comparison
with Rhodes grass and green panic.
Response to defoliation
Heavy grazing by hippopotamuses leads to dominance of Heteropogon
contortus around Lake Edward, Uganda, and still heavier use will lead to
poor Sporobolus and Aristida weeds (Heady, 1966).
Grazing management
Graze when the runners are well developed. Trampling by stock
will develop the ground cover. Graze well during summer to prevent if from
becoming stemmy. In pure stands or with Stylosanthes humilis keep it grazed
to 10-15 cm; with siratro let the pasture reach 30 cm (Bisset & Graham,
1978).
Response to fire
Good. An annual burn is necessary if grazing is not heavy.
Dry-matter and green-matter
yields
No records of yields have been found.
Suitability for hay and
silage
It has been made into hay before the grass becomes stemmy.
The hay has been eaten by horses and beef cattle but rejected by dairy
cattle (used to better material) and sheep. With siratro its palatability
is better. The hay is aromatic.
Value as a standover or
deferred feed
It is useful as low quality roughage but is rather stemmy.
Toxicity
The scent of the flower heads will not cause taint in milk
if eaten, though it deters cattle when more palatable feed is available.
Cultivars
The only registered cultivar is cv. Hatch after Garney
Hatch of The Caves, Rockhampton, Queensland, who sponsored its early acceptance.
It is described above.
Diseases
In a wet autumn a leaf rust (Puccinia duthiae) can reduce seed
yields.
Main attributes
Its ability to compete with native grasses on forest country
without nitrogen fertilizer and to invade Heteropogon contortus pastures.
Its hardiness and ease of establishment.
Main deficiencies
It lacks a little in palatability because of aromatic leaves.
Frost tolerance
Good. It has some winter hardiness.
Response to light
It does not grow well in shade.
Ability to compete with
weeds
Good.
Maximum germination and
quality required for sale
It is difficult to get more than 50 percent purity, though
germinations up to 70 percent can be obtained. Seed germination declines
rapidly after two years.
Pests
There are no major pests.
Palatability
It is reasonably palatable, much better than Heteropogon contortus,
and is improved in association with siratro.
Response to photoperiod
It flowers in late April and in November in central Queensland
(Bisset & Graham, 1978).
Natural habitat
Open bush and grassland, mainly in heavy textured black soils.
Tolerance to flooding
It will not thrive under waterlogged conditions.
Fertilizer requirements
Although able to persist in unfertilized ground it does respond
well to nitrogen fertilizer.
Compatibility with other
grasses and legumes
It will grow with native grasses and gradually dominate them.
Where tried, it combined well with siratro and Stylosanthes humilis (Bisset
& Graham, 1978).
Genetics and reproduction
2n=50, 60 (Fedorov, 1974).
Seed production and harvesting
It flowers twice a year in Rockhampton, Queensland, on the
Tropic of Capricorn, in autumn and late spring. For seed the pasture is
grazed till late summer and shut till seed ripens in late autumn. The crop
is direct headed. Clean seed plots have been established in Queensland
to prevent contamination with seed of Dichanthium aristatum (Angleton grass).
Seed yield: 10- 30 kg/ha with up to 80 kg/ha per crop with nitrogen fertilizer
and irrigation.
Economics
One of the few grasses suited to sowing in black self-mulching
clays. It has been used with fair success in reseeding the medium rainfall
areas of Baringo, Kenya.
Animal production
Around Rockhampton (rainfall 1 495 mm) on the Tropic of Capricorn,
carrying capacity is one animal to 1.2 hectares.
Further reading
Bisset & Graham, 1978.
Dormancy
There is little dormancy.
Value for erosion control
It is useful for erosion control on self-mulching black clay
slopes. It is one of the few suitable grasses as it establishes quickly
and forms a good ground cover. The runners do not take root readily, but
this is improved by prolonged wet weather, trampling or by soil cover,
and using high seeding rates. The pastures must be grazed or burnt periodically.
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