From shifting agriculture to sustainable rubber agroforestry systems (jungle rubber) in Indonesia: a history of innovations processes

The plains of Sumatra and Kalimantan were sparsely populated at the turn of the 19th century (less than 4 inhabitants/km2), and the local population relied mainly on shifting cultivation of upland rice. The introduction of rubber by Dutch private Estates in the 1910's triggered a radical change in the landscape but no fundamental change in farming practices, at least at the beginning, with the adoption of a rubber based agroforestry system. As right from the beginning, the Estates adopted monoculture as a way of maximizing rubber production, other farmers became aware of the possibility of growing rubber in a very extensive way by enriching their fallows (belukar) using the unselected rubber seedlings that were available and cost nothing. Planting rubber along with upland rice resulted in only a little additional work, involved almost no risks and, most important, no additional cost. Rubber grew together with the secondary forest in a complex agroforestry system (CAF) called 'jungle rubber". Productivity was sufficient to produce a very attractive income, but tapping of jungle rubber only starts after 8-15 years compared with 5-6 years with monoculture. The advantages of jungle rubber are clear: no cost, no labour required for maintenance during the immature stage, income diversification with fruits, rattan, timber and other NTFP (non timber forest products) in the agroforest system. There are also indirect environmental benefits in soil conservation and rehabilitation of degraded lands. Alongside their rubber production, farmers continued to slash and burn new plots every year but less than before. Estates began organizing their own research programme in the 1920's, which led to the adoption of fertilization, an increase in weeding the use of improved planting material (clones), which had the most significant effect in terms of yield. Meanwhile farmers began to develop their own innovations that can be called "endogenous technical innovations" mainly through the improvement of certain rubber cultivation practices such as planting in lines, minimum weeding (once a year), intercropping during the immature stage. At that point, as the farmers’ primary aim was to set up a rubber system that minimzed capital and labour requirements, they shifted from an "enriched fallow with rubber" to a real "complex rubber agroforestry system". As jungle rubber productivity is low (500 kg/ha/year of rubber) compared to that of estates using clones (1500 to 2000 kg/ha/year), and as they had exhausted the possibilities represented by endogenous innovation of production, farmers began to consider including "external technical innovations" such as clones, fertilization and good tapping systems and the use of a very effective herbicide for Imperata cylindrical (Round-UP) as it decreased the cost of labour for maintenance during the immature stage. The planting of perennial trees (or their selection among specimens that had regenerated naturally) such as fruit and timber trees was another innovation that began in the 1980’s.However, these practices were still forbidden in rubber development projects in 1994. An increase in the density of the population, land scarcity in some areas, and opportunities to plant other more productive crops forced farmers to change to a more productive Rubber Agroforestry System (RAS). Recent agroforestry research has focused on how to integrate indigenous knowledge about jungle rubber with external technical innovations to increase productivity while conserving the benefits of agroforestry practices in terms of environment and biodiversity. The last phase is now underway with improved agroforestry systems available for farmers at low cost and low labour input. This has implications in terms of research and development policies, in particular with the use of the so-called “partial approach” by new farmers.