SCI-TECH & AGRI

Multi-purpose leguminous tree

By Our Agriculture Correspondent

The multi-purpose tree is a boon to the dryland farmers of the tropics.

The multi-purpose tree is a boon to the dryland farmers of the tropics.  

A FAST growing, multi-purpose tropical leguminous tree, Gliricidia sepium, adapts well in a wide range of soils, and enhances soil fertility and productivity.

"This tree is used for timber, firewood, medicinal purpose, charcoal, live fences, plantation shade, soil stabilisation, livestock feed and as green manure," says Dr. S. P. Wani, Principal Scientist (Watersheds), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh.

Gliricidia does well even in eroded and acidic soils with low pH of 4.5, and also in alkaline soils. It can tolerate fire and the trees quickly re-sprout with the onset of rains, according to Wani.

"Green leaf manuring is an important farming practice for increasing organic matter content in the soil. In highly degraded soils, especially in the tropics, soils lack sufficient amount of nitrogen. Green leaf manure plants such as Gliricidia can increase the soil fertility," explains Dr. Wani.

Growing Gliricidia on farm buds serves a dual purpose of producing green leaf manure rich in nitrogen, under field conditions and also helps in conserving soil through reduced soil erosion, according to him. The ICRISAT in collaboration with Andhra Pradesh Rural Livelihoods Programme and Asian Development Bank (ADB), Philippines, is popularising the concept of raising Gliricidia on the farm bunds and using it as green leaf manure for the farm.

The tree is propagated through vegetative cuttings or seeds. Stem cuttings or 3 to 4 months old seedlings can be planted on bunds at an espacement of 50 cm during the rainy season. A closer spacing of less than 20 cm between the plants is recommended in steep slopes.

The stem cuttings will establish well and grow faster than the seedlings. One year after planting, farmers can harvest the leaves by lopping the plants at 75cm above the ground.

For good management, plants should be pruned at appropriate time. Pruning should be done at least thrice a year — in June (before sowing the rainy season crop; in November (before sowing the post-rainy season crop); and in March (before sowing of the summer crop).

The lopping is cut into small pieces. The chopped material is applied to the soil surface as mulch or incorporated into the soil as green manure, according to Wani.

The mulch increases the organic matter content in the soil. It adds valuable nutrients such as nitrogen, phosphorus, potassium, calcium and magnesium to the soil. The plants grown on 700 m long bunds can provide about 30 kg nitrogen per hectare in a year under rain fed systems with 700-800 mm annual rainfall, according to him.

It also will act as barrier and filter the rainwater running down the slopes. It will reduce the environmental risks associated with chemical fertilizers.

Gliricidia plants will serve as the pioneer species for the establishment of other plant species. Its leaves are used as insecticide and insect repellent. A mixture of ground leaves or bark and cooked seeds are used as poisonous bait for managing rodents in farms, according to Dr. Wani.

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