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PLANTING
Seed treatment: the seed has a covering (testa) which is hard, waxy and almost
impermeable to water, so to ensure good germination the seed should be treated first.
There are many methods; for small quantities the seed can be scarified by cutting a
small “nick” in the side of the seed (not the base) with a knife or nail-clippers, or by
rubbing it with sandpaper. For larger quantities, either immerse seed in 80°C water
for 3 minutes or immerse the seed, in a mesh bag, in an equal volume of boiling
water. Remove heat at the same time as the seed is immersed, remove bag after 3
minutes. In both cases the seed should be rapidly cooled in cold running water, then
dried completely on a concrete or other hard floor, or in hessian bags.
Inoculation: a suitable strain of Rhizobia should be used if available. Also the seed
should be lime-pelleted if sown in soils below pH 5.5, or if sown in contact with
superphosphate.
Propagation: by seed, but Leucaena can also be propagated with cuttings or grafts.
The plants coppice readily, producing what are known as “ratoons” or “pollards”.
Soil: not well suited to acidic soils less than pH 5, nor poorly drained soils.
Leucaena needs calcium and grows well on deep, calcareous or clay soils. Very salt
tolerant, but sensitive to aluminium. Needs zinc, molybdenum and other nutrients
(see “Limitations”, below).
Seed rate: 0.5–5 kg/ha depending on type, row spacing, soil type, etc. 20–30,000
seeds per kg.
Spacing: the Salvador types are often grown very widely spaced to allow maximum
growth.
Depth: 2.5–5 cm
Intercropping: for grazing, grasses are usually planted, such as green panic, setaria,
Rhodes grass or kikuyu grass. For soil enrichment, erosion control, etc. Leucaena
can be intercropped with almost any crop.
GROWTH CONDITIONS
Growth period: a perennial. Seedlings grow slowly—less than 30 cm in the first six
weeks.
Rainfall: optimum is 600–1700 mm per year, but can sometimes survive with 250
mm per year.
Temperature: grows best in full sun in hot places. Loses leaves (it “defoliates”)
with even light frosts, but soon recovers.
Altitude: best below 500 m; Leucaena does grow at high altitudes, but with less
vigour. Latitude seems to make a difference to which altitudes are suitable.
Peru—up to 15 m tall, with many branches even low down on the trunk. A
quite recent discovery, so only relatively few improved varieties are available.
Mainly used for grazing.For grazing, 1.5–5 m between rows, giving 75,000–100,000 plants/ha.
For timber, about 2 m 2 m, giving 2500 plants/ha. ×