Improvement of forage productivity in plantation crops

• Rubber Research Institute of Malaysia, Malaysia
• Udayana University, Indonesia
• Sam Ratulangi University, Indonesia

Plantation agriculture is strongly developed in Southeast Asia and the South Pacific, and production of forages under plantation crops would maximise resource use, diversify farm income and have positive effects on soil fertility and stability and on weed control.

This project will undertake collaborative research with the long-term goals of improving understanding of forage/plantation systems and generating innovations to make improved adoption feasible.

Level of shade is the most significant factor determining output from pastures grown in plantations. Accordingly, the scientists' tasks are: to evaluate new species for shaded environments; to assess shade effect on nutritive value, plant competition and nitrogen economy of pasture species; to study the management and productivity of plantation/forage systems; to survey the natural forage resources at collaborating sites.

Collaborating sites have been chosen in Malaysian rubber plantations and Indonesian coconut plantations to provide a representative range of crops and livestock species (sheep and cattle) and to evaluate intensity of use (free or tethered grazing or cut and carry for stalled animals).

Evaluation of forage species for shaded environments will include identification of new elite germplasm, especially that originating in shaded environments. Potentially shade-tolerant grasses and legumes will be studied using automatic irrigation facilities in the open at the University of Queensland. Sarlon shade cloth will facilitate measurement of yield and persistence under shade. Species that demonstrate substantial shade tolerance will be examined for other desirable agronomic characteristics and environmental adaptation. Local and imported germplasm of the promising Stenotaphrum secundatum will receive special attention, as will C3 Panicum species, many of which originated in shaded environments.

Selected material that exhibits shade tolerance and other appropriate traits (which will vary from site to site) will be tested in field plots in plantations at all the collaborative sites for yield, adaptation and persistence under regular defoliation.

Plot trials at St Lucia will assess the effects of shade on nutritive value, plant competition and nitrogen economy of the species. Laboratory analyses of plant parts for in vitro digestibility and chemical composition will complement intake and digestibility measurement using pen-fed animals. Studies on grass-legume competition in reduced light will explore adaptive characteristics such as differences in the balance between photosynthesis and respiration, partitioning of assimilate and adjustment of canopy morphology and leaf anatomy. In addition to the plot trials, field and glasshouse studies respectively will probe nitrogen nutrition of shaded grass and the relative sensitivities to shade of plant growth and nitrogen fixation in legumes. In Indonesia, penned feeding trials with small ruminants will serve to confirm the results.

In Malaysia, grazing trials will investigate the influence of sheep grazing on forage composition and production (and hence liveweight gain potential) in rubber plantations, and on weed control there. Forage types range from leguminous swards in well managed young plantations to pastures of broad-leaf weeds and naturalised grasses in mature ones. Chemical and mechanical weed-control treatments will be included in some trials to determine the need for integrated control methods.

The project will survey forage resources and environmental conditions in Malaysian rubber-production areas and Indonesian coconut plantations, to assemble relevant baseline data. The work at Bali will concentrate on the relatively new coconut/vanilla/cattle system.

As well as identifying new species for shaded environments, the project should provide a better understanding of the effects of shade on nutritive value of forages and on their nitrogen nutrition, and of various plantation/crop/livestock systems.