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| Title | RAS-3: The Conversion of Degraded Imperata Grassland to Productive Rubber Agroforest in West Kalimantan | | Author | Elok Mulyoutami, Ilahang, Diah Wulandari, Laxman Joshi, Gede Wibawa and Eric Penot | | Year | 2008 | | Publisher | World Agroforestry Centre - ICRAF, SEA Regional Office | | City | Bogor, Indonesia | | Call Number | PO0151-08 |
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| Abstract: |
| Imperata grassland already covers large areas of West Kalimantan with little production function. Trials of rehabilitation of Imperata land for planting para rubber (Hevea brasiliensis) indicate that this is possible with limited resource (labour including) input. These rubber agroforests can not only increase farmer income, but also provide better environmental services than from Imperata covered land. The RAS-3 on-farm trial in West Kalimantan, was a part of the large network of rubber agroforestry systems in Indonesia. Annual crops (rice, chilli, vegetables) are grown in the first year only, with non-vine cover crops grown immediately after the rice harvest (Mucuna, Flemingia, Crotalaria, Setaria and Chromolaena) or multipurpose trees (such as Gliricidia), or fast growing trees (FGT) produced for pulpwood (Paraserianthes falcataria, Acacia mangium and Gmelina arborea). Shading from these trees suppresses Imperata growth.
Potential of cover crops to suppress Imperata growth varied between species. Pueraria, a creeping legume was the most effective suppressor of Imperata; Mucuna also performed well but both required regular ‘weeding’ to avoid their vines strangling young rubber trees. Among the erect legumes Flemingia proved better, but Crotalaria proved ineffective. Rubber trees in control plots (without cover crops) had the slowest growth. The FGT trials in Trimulya village showed that all FGTs were only partly successful in controlling Imperata regrowth. Rubber growth in FGT mixed plots was better than in Imperata or Chromolaena infested plots, this was far behind the rubber growth in plots with legume crops. The time for rubber trees to reach tapping size was prolonged by more than a year compared to those in LCC (Pueraria and Mucuna) plots. The FGTs, particularly Acacia, grew rapidly and affected rubber trees in the first years; hence farmers cut down all remaining FGTs in the third year.
Pueraria and Mucuna are effective in controlling Imperata, however these require periodic ‘weeding’ to prevent strangling of rubber plants. Seeds of Pueraria and Flemingia are unavailable locally and Mucuna requires repeated planting. FGTs are a potential income source in future and they can suppress Imperata. To avoid the impact of their aggressiveness (particularly of Acacia), they may be planted 2-3 years after planting rubber; Pueraria and Mucuna can be incorporated in these first few years. |
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