R. C. Gutteridge

The scope and potential of tree legumes in agroforestry

Tree legumes play a vital role in many agroforestry systems currently in use throughout the world. Because of their multipurpose nature they can be used to provide high quality fodder for livestock, nutrient rich mulch for crops, fuelwood and timber, microenvironment amelioration, ecosystem stability, and human food.Tree legumes are increasingly being used to provide fodder for livestock, as they have a number of unique characteristics which make them attractive for both smallholder and largescale livestock enterprises. Research and development efforts have concentrated on broadening the resource base by evaluating a greater range of tree legume genera, defining optimum management strategies, and developing appropriate systems which capitalize on the advantages of these species.This paper reviews the role of tree legumes in agroforestry, especially for fodder purposes, outlines the areas of current research focus, and endeavors to highlight some gaps in our knowledge which require further research effort.

Agronomic evaluation of Leucaena. Part 1. Adaptation to environmental challenges in multi-environment trials

A multi-environment trial was conducted to evaluate the performance of high yielding accessions from most taxa of Leucaena, for broad and specific adaptation to growth-limiting environments, and to develop an understanding of environmental parameters limiting growth of this important multipurpose tropical tree-legume genus. Eighteen sites were selected to include environments known to constrain the growth of L. leucocephala. Accessions were planted in replicated line plots, with 10 trees/plot, spaced 50 cm apart, and with rows spaced 3 m apart. Environmental parameters measured were maximum and minimum temperatures, rainfall and psyllid pressure. Soil fertility and acidity indices were derived from soil analyses. A KX2 F1 hybrid accession proved broadly adapted with high yield rankings in all environments, and with yield advantage greatest at low temperature and high psyllid pressure sites. Specific adaptation to low temperature environments was identified in L. trichandra OFI53/88, and to a lesser extent in L. pallida CQ3439. No accessions were specifically adapted to acid-infertile soils. Highest dry matter production was achieved in fertile, hot, humid, low psyllid environments. Very low growth rates were achieved in acid-infertile and low temperature environments. Yield was strongly reduced by mean monthly minimum temperatures of 22 °C, mean monthly maximum temperatures of 29 °C, psyllid pressure of >2.5 (1–9 scale of increasing pressure based on damage to young leaves), acidity index of 6 (1–7 scale of decreasing acidity based on soil and Al saturation) and fertility index of 9 (1–12 scale of increasing fertility based on critical soil nutrient levels).

Wood and biomass production of Leucaena in subtropical Australia

Although only Leucaena leucocephala is widely used, most members of the Leucaena genus have potential as multipurpose species for tropical agroforestry systems. To investigate the wood and biomass production potential of the Leucaena genus, 116 accessions covering the 22 species were evaluated over a two-year period at Brisbane, southeast Queensland, Australia. Trees were planted into replicated line plots 5 m long, with rows spaced 3 m apart. Trees were initially planted at 0.5 m spacings within the plots, but were thinned to 1 m spacings prior to the evaluation period. The hybrid accessions, KX2 (L. pallida × L. leucocephala) and KX3 (L. diversifolia × L. leucocephala), were the most productive, yielding over 50 kg dry matter (DM)/tree. L. trichandra OFI53/88 and L. diversifolia CPI33820 were the most productive non-hybrid accessions producing total yields of 41 and 37 kg DM/tree, respectively. Cultivar Tarramba (26 kg DM/tree) was the most productive of the 26 L. leucocephala accessions assessed in the trial but all these accessions suffered from psyllid (Heteropsylla cubana) attack at this site. A series of non-destructive growth measurements was recorded every three months over the two-year evaluation period. Root collar diameter (RCD), stem number and plant height were found to be the most useful of the measurements for non-destructive assessment of accession agronomic characteristics. A relationship between yield and a growth index (calculated as RCD2 × Height/1000), was derived from data from all accessions and could be used as a reliable predictor of yield (r2 = 0.94). The widespread use of the F1 hybrid leucaenas is currently limited by a lack of seed. Technologies to economically produce F1 hybrid seed on a commercial scale are required before the potential of these accessions in agroforestry systems can be fully realized.

The productivity of Tipuana tipu under three cutting regimes in southeast Queensland

The tree legume Tipuana tipu, which has potential as a browse species in sub-tropical regions, was subjected to three cutting frequency regimes of 6, 8 and 12 week intervals at a cutting height of 1 m. Cutting at 12 week intervals gave a total leaf yield of 4.02 t/ha/year which was significantly higher than the other two treatments. There was 100% survival of all plants in all treatments over 2 years and the implications of the results for the management of Tipuana tipu in a hedgerow system for folder production are discussed.

Report on the Second International Short Course ‘Fodder Tree Legumes — Multipurpose Species for Agriculture’

The Department of Agriculture, University of Queensland in conjunction with CSIRO, the Queensland Department of Primary Industries and the Queensland Forest Service conducted a short course on the above topic in Queensland from November 1 to December 11, 1992. Twenty-four participants from 13 countries attended the course. Participants came from the South Pacific Region, Southeast Asia, South Asia, Africa and South America. The six-week course was planned to provide a mix of lectures, field and farm visits, participant seminars and workshops. The lectures and practical demonstration detailed information on the use of exotic and native Australian fodder tree legumes in the grazing industries of tropical and sub-tropical Australia. The range of fodder trees available to agriculture, their environmental adaptation and role in animal production were outlined and reviewed. In addition the multipurpose nature of these species was also emphasized by examining their role in soil fertility improvement, erosion control and fuelwood production. Thirty-six lectures on these topics were presented to the participants during the course. A twenty-one day coach tour was the highlight of the course enabling participants to inspect production systems utilising fodder tree legumes in contrasting environmental conditions. The tour included the arid regions of western Queensland around Charleville and Longreach, the more humid locations in Central Queensland near Rockhampton and Gayndah and up to the monsoonal and wet tropics of far North Queensland around Townsville, Innisfail and the Atherton Tableland. During the course, all participants were asked to design a project which could be implemented in their home countries based on information they had received from the course. This assignment consisted of the preparation of a written document as well as the presentation of a 20-minute seminar in the last week of the course. All participants received a course certificate which was presented by the Head of the Department of Agriculture at the conclusion of the course. The success of the first and second course has prompted the course co-ordinators to organize a third similar course which will be held in November and December 1994. For further information on the third course please contact: