Acid soils, which cover nearly 54% of the land area, are a major constraint to the increased, sustainable food production that is vital to the growing populations of Southeast Asia. Once cleared, these soils rapidly lose their fertility. Plant growth is inhibited by one or more factors, including low pH, aluminium and manganese toxicity, deficiencies of calcium, magnesium, potassium, phosphorus and micronutrients, and susceptibility to erosion and water stress.
The problem has been recognised for some years by the International Board for Soil Research and Management (IBSRAM) and ACIAR. An earlier ACIAR project (8375), which ended in June 1990, focused on the use of inorganic fertilisers to correct soil acidity in Malaysia. This was complemented by studies on soil chemistry and plant nutrition at the University of Queensland. At an ACIAR/IBSRAM workshop in 1989, seven countries expressed the need for assistance in developing research programs aimed at increasing production of food crops on acid upland soils. Four of these countriesMalaysia, Thailand, Indonesia and the Philippineswere selected as collaborators in the present project. After a review meeting in May 1993 two Vietnamese groups were added to the project.
In the new project, basic research at the University of Queensland will complement and strategically support more applied field studies by the collaborators in Southeast Asia. Decisions on the common methodology to be used by developing-country collaborators were made at an AIDAB-funded training workshop organised by IBSRAM in Thailand in June 1990. University of Queensland researchers and all collaborators of the ACIAR project and the IBSRAM network attended.
The objective of project 8904 is to develop improved soil management technologies in order to sustain food crop and other agricultural production. Two field trials will be conducted at one site in each of the five collaborating countries: one on the management of acid soils, the other on the alleviation of soil acidity through organic amendments. The sustainability of cropping systems involving corn and groundnut with low, medium or high inputs will be a particular focus. Soil samples from the field trials in Southeast Asia will be sent to the University of Queensland for inclusion in research on the solutionsolid phase chemistry of acid soils being undertaken there. Resulting analyses will supply data to the developing country partners that will enhance the interpretation of field trial results.
The University of Queensland group will determine the mechanisms by which organic matter additions to acid soils alleviate aluminium toxicity and other limitations to plant growth; assess the effects of organic matter incorporation on the lime requirement of acid soils; and identify those components of organic matter responsible for short-term and long-term protection of nodulation and plant growth from aluminium toxicity. Research methods will involve a laboratory study of the solution and solid phase chemistry of acid soils ameliorated with organic and inorganic amendments; controlled environment studies of plant response on acid soils amended with these materials; and solutionculture studies to determine plant response to potentially aluminium-toxic solutions containing different organic compounds. Acid soils used in the research will come from Australia, as well as from the field trial sites in Southeast Asia.
The project will create new opportunities for increasing small farmer income, either in the form of extra cash or extra food for home consumption. New management practices introduced as a result of the project will permit a larger range of crops to be grown and a greater crop yield. The project will be linked into IBSRAM’s network ‘Management of Acid Soils in the Humid Tropics of Asia’, providing a more cohesive and effective approach to the solution of the complex problems facing small farmers on acid upland soils in Asia. Because of the linkage, the developing country collaborators will also benefit from a range of additional services and benefits provided by IBSRAM.