Production and utilisation of shrub legumes in the tropics

• Balai Penelitian Ternak, Indonesia
• Udayana University, Indonesia

In many tropical areas, shrub legumes are multipurpose plants, being used in subsistence agriculture for fodder, hedges, shade, fuelwood, erosion control, and as a source of nitrogen for other crops. Compared with herbaceous legumes, they have potentially higher yields and retain more leaf into the dry season. They can grow above the reach of livestock, and so feed may be conserved until required.

Animal production is increasing in Southeast Asia. In Indonesia, marked increases in forage production will be needed to support more animals. Some of this requirement will be met by increasing the area under forage; however, the major support must come from improved production per unit area.

This project concerns the development of methods for growing and using shrub legumes in the tropics. Because they do not provide human food, shrub legumes are generally grown on poorer quality land. The project seeks to determine the best species and fertiliser applications for growth on a wide range of soils in Indonesia and Australia. In addition, it will investigate what management regimes are likely to produce the highest levels of production in some promising shrub legume species and evaluate a range of species for use in animal production.

The research involves close collaboration between the CSIRO Division of Tropical Crops and Pastures, which has considerable expertise in forage research, and two Indonesian institutions, Balai Penelitian Ternak (BPT) of the Agency for Agricultural Research and Development (Indonesia) and Udayana University (Denpasar). It follows logically from ACIAR Project No. 8363, developed by the Division of Tropical Crops and Pastures following workshops and discussions in the early 1980s. Results of that project provided indications of the fertiliser applications (mainly phosphorus) needed for high levels of production of Leucaena leucocephala and other shrub legumes on the acid infertile soils, and also of promising species that are not yet widely grown.

The present project builds on knowledge of the nutritional requirements of shrub legumes, the management of some species for optimum yields, and the value of these for animal feed. The increased knowledge will improve the living standards of subsistence farmers throughout the tropics by providing suitable forage species and appropriate management practices. In addition, the availability of a range of shrub legume species will provide alternatives to leucaena, which has sufferered considerable damage from jumping (psyllid) lice that have entered Southeast Asia in recent years.

The collaborative work will continue the multi-site species testing and nutrition experiments established under Project No. 8363: it is necessary to obtain data for another 1.5--2 years to fully evaluate the worth of the perennial shrub legumes and the long-term effects of six different fertiliser treatments. The experiments are established at four sites (two in Indonesia and two in North Queensland) and are being carried out by CSIRO in conjunction with BPT.

In addition, new agronomic experiments are determining the effect of cutting height and cutting interval on the yield of a range of selected legumes that have demonstrated the capacity for high yield in their first year of production. And animal feeding trials being carried out in Indonesia and Australia are comparing the relative nutritive values of leucaena and a range of other shrub legumes as sources of protein supplement for goats and sheep on low quality diets.

Scientists at Udayana University are undertaking glasshouse plant nutrition studies in conjunction with CSIRO. In these, they are measuring the nutritional responses of three shrub legumes on a wide range of soils taken from throughout Indonesia, having leucaena as the standard. The soils include not only those studied in Project No. 8363, but also non-acid ones from other areas where shrub legumes would be valuable. Glasshouse studies on methodology of pot experiments, including the importance of mycorrhizae, are also being undertaken at CSIRO Davies Laboratory, Townsville.