Desert’s Wonder Grass: Sewan

Lasiurus hirsutus Boiss.

Graminae

Synonyms

L. scindicus Henr.; Elyonurus hirsutus (Forsk.) Boiss.

Common names

Sewan grass (Rajasthan, India), karera (Pakistan).

Description

A perennial, almost sub-woody at the base, with wiry, glaucous stems, leaf-blade thin with a setaceous tip, racemes 10 cm long, densely white villous, spikelets often three at each node, two sessile and one pedicelled; sessile spikelets 6-9 mm long, the lower glume flat, hirsute (Hutchinson & Dalziel, 1954). It has the maximum quantity of root material in the top 0.03 m3 of soil.

Distribution

North Africa, Mali, Niger, Ethiopia, Iraq, southern Pakistan and north-west India.

Rainfall requirements

It occurs in rainfalls below 250 mm a year. One of the dominant species in arid zones with as low a rainfall as 12.5 mm in Rajasthan (Dabadghao & Shankarnarayan, 1973).

Drought tolerance

Excellent.

Soil requirements

It grows best on alluvial soils or light brown sandy soils with a pH of 8.5.

Sowing methods

At Jodhpur, Rajasthan, it is best sown in rows 30-90 cm apart and weeded once (Chakravarty & Verma, 1972). In Thal, Pakistan, it is germinated in earthen tubes about 30 cm long and then transplanted in these tubes into the sand dunes at distances of 2 x 2, 3 x 2, or 3 x 3 m, with the top of the tube buried 10 cm in the sand. Protect the plants from wind, using reed windbreaks, till well established (Khan, 1968).

Sowing time and rate

Transplant the tubes during rain or within 24 hours after rain has fallen (Khan, 1968).

Seed treatment before planting

Chakravarty and Bhati (1969) made 5 mm diameter pellets containing one or two spikelets with a mixture of fine silt and cow dung. Germination was not affected and the best stand came from two spikelet pellets stored for four months.

Response to defoliation

At Jodhpur, Rajasthan, the highest dry-matter yields were obtained by cutting at 30-day intervals to a height of 15 cm (Dabadghao, Roy & Marwaha, 1973).

Dry-matter and green-matter yields

2 700-10 500 kg fresh forage per hectare (Verma & Chakravarty, 1969) and dry-matter yields of 1 500 kg/ha (Chakravarty & Verma, 1972). Well-established swards in western Rajasthan yielded 3 400 kg DM/ha (Ahuja, 1972).

Cultivars

Strain 318 is recommended by Prasad and Singh (1973) for cultivation under dryland conditions in western Rajasthan.

Main attributes

Its drought resistance, its persistence on sand dunes and its palatability.

Latitudinal limits

25-27°N.

Palatability

Good, one of the first grasses to disappear under the impact of grazing.

Chemical analysis and digestibility

No figures have been cited.

Natural habitat

Large bushy thickets in sandy deserts.

Fertilizer requirements

At Jodhpur, Rajasthan, application of 0-40 kg N + 20 kg PO: + 25 kg K2O/ha gave a yield of 4 860 kg/ha. Increasing nitrogen from 0-20 kg/ha increased yield from 3 500 to 5 810 kg/ha, but yields declined with further increases in nitrogen rates (Bajpai & Jain, 1971).

Compatibility with other grasses and legumes

Sowing with Vigna radiata(Mung), V. aconitifolia(Moth) and Cyamopsis tetragonoloba(Guar Gum) increased forage production by 1736 percent when rainfall was adequate, in the first two years, but the legumes failed in the third year due to drought (Daulay, Chakravarty & Bhati, 1972).

Genetics and reproduction

2n=56.

Economics

One of the most important arid zone grasses in north-west India.

Animal production

At Jodhpur, Rajasthan, carrying capacity was 4.2, 0.29 and 7.1 cattle units per hectare in 1968/69, 1969/70 and 1970/71 respectively, with annual rainfalls of 178.8, 92.7 and 594.8 mm respectively (Gupta, Saxena & Sharma, 1972).

Further reading

Chakravarty & Bhati, 1969; Chakravarty & Verma, 1972.4

Dormancy

Germination increases with storage up to four months.

Value for erosion control

It is useful stabilizing sand dunes in Iraq (Dougrameji & Kaul, 1972).

Tolerance to salinity

It has a moderate tolerance to salinity.

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Filed under COW PROTECTION, FODDER

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