Alternatives to slash and burn in SE Asia, phase 3: Facilitating development of agroforestry systems

FST/2001/020: Alternatives to slash and burn in SE Asia, phase 3: Facilitating development of agroforestry systems

Indonesia

World Agroforestry Centre, Indonesia

Dr Meine van Noordwijk
Phone: 62 254 1625415
Fax: 62 2541 625416
Email: m.van-noordwijk@cgiar.org

• Queensland Horticulture Institute, Australia
• Lampung University, Indonesia
• Forest and Nature Conservation Research and Development Centre, Indonesia
• Center for Soil and Agroclimate Research, Indonesia
• Indonesian Agency for Agricultural Research and Development, Indonesia

$301,900

01/01/2001 - 31/12/2003

01/01/2004 - 31/12/2004

Dr Russell Haines

This project was a phase of the global Alternatives to Slash and Burn (ASB) program, a system wide initiative for which ICRAF is the convening institution and coordinator. It built on two earlier phases. The broader aim of ASB is to identify and test innovations that will help eradicate poverty while simultaneously curbing the environmental problems associated with deforestation. The emphasis is on working with farmers to understand their needs and constraints, and jointly developing and testing options that might ensure environmental improvement while maintaining profitability and viability of farming practices. A longer-term goal is to build community groups than can further develop and refine local conservation measures. The research for this project took place in Sumatra, within the study area of previous ASB phases. It focused on agroforestry options for landholders at the farm level to reduce soil loss and enhance water quality through enhanced landscape filter function, using trees and other vegetation management.

The research was designed to address the following objectives (i) evaluation of promising management practices that meet farmers' preferences while lowering soil loss to tolerable level; (ii) validation and refinement of the management practices considered in the first objective in a series of trials; (iii) evaluation of the role of litter layers - as generated from different stages and systems of coffee farming - on soil structure, run-off and soil loss; (iv) defining the level of susceptibility to erosion in the Wai Besai sub-watershed.

This research focused on the options farmers have for improving their farms and recovering forest functions, by enhancing 'landscape filter' and increasing agrodiversity. The two-pronged technologies - income generation and natural resource management - are needed in the negotiation support system (NSS) scheme in Sumberjaya, West Lampung Province, Indonesia, a site representing land management conflict in forest margin, due to forceful eviction of farmers and uprooting of their well-developed coffee by the forestry service in mid 1990s because the farmers farmed within protection forest zone. In this NSS scheme the communities who have farmed on land under government jurisdiction can receive a semi-permanent land title (about 25 years) if they commit to restore the forest functions.
This research included plot- and micro-catchment-scale erosion measurement, evaluation of tree contribution to litter and soil fertility rejuvenation, and farmer-led tests of soil conservation treatments in coffee-based farming systems.

Results showed that coffee trees play a significant role in controlling erosion, with maximum effect when the coffee is planted in combination with other trees in a multistrata system. Such as system produces a complex canopy architecture that protects soil surface against heavy raindrops. Also effective is the formation of tree litter on the coffee floor or the addition of conservation measures such as cover crops grown on young coffee farms.
The researchers produced agroforestry/soil conservation options articles and booklets and a map of soil erosion susceptibility. Published results from the project can offer advice to other agroforestry-related endeavours.
The initial research activities summarised background information of the case study site and compiled a range of conservation options in coffee-based agroforestry systems, which are very central in the NSS. Farmers will benefit from this research because it offers wider options of conservation technologies than they currently practised in their localities. The local forestry and agricultural services also have additional access to wider options of conservation measures that can provide environmental benefits.
Plot- and micro-catchment-scale measurements have produced convincing evidence of the effects on soil erosion and runoff of different stages of coffee growth and different soil conservation treatments. Soil loss in the Bodong site was the highest (about 85 tonnes per hectare per year) under 1 year old coffee and this dropped sharply as the coffee canopy developed. Under 5-year or older coffee the soil loss was basically within the tolerable level; multistrata coffee tended to be more protective against soil loss than monoculture coffee. Under 12-year-old or multistrata coffee (which generally equates to coffee 8 years or older) soil loss was basically as low as that under forest. Thus, at this stage, additional soil conservation measures do not further reduce soil loss.
Equally important, these activities have provided information on the breadth of variation in soil properties and how important this is in influencing soil susceptibility to erosion. For instance, under 3 to 4 year coffee stands with about 500 mm of rainfall during the 3-month period of measurement, soil loss was negligible (<2 tonnes per hectare) in Tepus and Laksana sites, but it was about 37 t/ha in Bodong site. This difference was attributed to distinct differences in soil structure. Because of the variation, researchers developed a map of soil susceptibility to erosion. This map is assisting the local government in prioritising areas for implementation of soil conservation.
The researchers recognised the value of tree litters produced by old and/or multistrata coffee in protecting soil surface against soil loss, reducing runoff, increasing soil organic carbon and increasing soil macropores. These qualities are close to that provided by the natural forest, suggesting that helping the local farmers to maintain a tree-based, multistrata land-use system on the steep forest margin is a judicious option and one that will speed up the recovery of forest functions.
The intervention made by the government in the mid 1990s to evict the farmers and replace coffee with Calliandra callothirsus was out of focus and only harmed the farmers because it left them with almost no source of alternative income. Erosion and runoff reduction, the two forest functions most commonly voiced by the government, have clearly been reduced as the canopy of coffee (and other trees in the multistrata system) and litter on the coffee floor developed. Additional conservation intervention is necessary only for selected sites with low infiltration capacity/low porosity. Facilitation of the development of multistrata systems appears to be the wisest way for the government to proceed.
At the end of this three-year study the research had dispelled some of the myths about the natural resource functions and opened up a range of wider options in soil conservation. Researchers also delineated the 'hot spots' in the watershed where extra efforts in soil conservation are needed.