The Leucaena Network
Leucaena has some very important environmental benefits
• Nitrogen fixed by leucaena reverses nitrogen run-down and improves soil fertility, promotes better grass growth and improved animal production.
• Leucaena grown in association with a vigorous and adapted grass (e.g. Buffel, Rhodes, Green Panic) will help to prevent soil erosion.
• The deep rooting habit of leucaena can extract water from the soil to a depth of 3 - 5 metres thus preventing rising water tables that can bring salt to the surface and cause dryland salinity.
• As a woody-stemmed tree, leucaena acts as a carbon sink by sequestering significant amounts of carbon from the atmosphere in its woody frame and in additional soil organic matter.
• Similarly, methane emissions from cattle grazing leucaena are substantially lower than for tropical grasses, up to 40% lower, probably due to the high digestibility and condensed tannin content of leucaena forage.
Leucaena as a weed: a word of caution
Leucaena produces viable seed and can cause weed problems in ungrazed areas such as gullies, banks of watercourses and road verges. The 'common' leucaena (i.e. L. leucocephala ssp. leucocephala) that arrived here over 120 years ago has shown this. The cultivated ssp. glabrata cultivars will also colonise ungrazed areas if they are allowed to escape from grazed plantations and precautions should be taken to prevent this.
The Leucaena Network of growers (formed in 2000) have recognized this and prepared, adopted and released a CODE OF PRACTICE in August 2000 that is promoted widely among growers. The CODE OF PRACTICE highlights the need to manage leucaena to minimize the risk of escape and to control any plants that move from the planted area. This CODE is consistent with the Queensland Government’s policy to reduce the weed threat of leucaena adopted four years later in November 2004.