Changes of soil properties and input-output balance of nutrients in land-use systems following rain forest conversion in Central Sulawesi, Indonesia

Indonesia has nearly 50 % of Asia’s and 10 % of the worlds remaining tropical rainforest, but deforestation rates are among the highest worldwide and rainforest area is declining rapidly (FAO 2001). The most important factor for deforestation is agriculture. We wanted to study the sustainability of land-use systems in conversion areas in respect to soil fertility. We studied maize- and cacao/coffee-agroforests, which are the main non-irrigated land-use systems of the upland rainforest margin areas in Central Sulawesi. The study objective of this study were: • To quantify changes of soil properties under maize cultivation and agroforestry compared to natural forest and to measure the effect of the duration of cultivation (chronosequence). • To measure the input-output balance of nutrients in maize and agroforestry compared to natural forest. Soils were generally fertile, with high base cation saturation, cation exchange capacity and pH-values. Carbon and nitrogen-stocks were highest in natural forest and lower in maize and agroforestry. In maize both C and N decreased with time, whereas in agroforestry they increase