PT Rea Kaltim owns 27,000 hectares planted to oil palm in the River Belayan area, around 140 km northwest of Samarinda, in Kalimantan Timur province, and has plans to reach 75,000 hectares by 2014. The region is very wet, with 3,500 mm of rainfall per year, the relief is moderately undulating to hilly, the soils are clay of the ochre podzolic type. The positive points identified at PT Rea Kaltim for future collaboration over the long term are: -good documentation, -a good command of cultural techniques, -a spirit of innovation and search for quality through expertise, -a strong commitment to environmental matters, with some considerable results achieved. This mission on cultural practices consisted in dealing with agronomic questions in a stringent scientific manner, seeking causes and then proposing efficient, practical and cost-effective solutions. In terms of fertilization in particular, CIRAD's long-standing and vast experience throughout the Tropics has enabled us to develop a mineral nutrition management method for oil palm plantations based on leaf analysis and field trials. In this way, the partner gradually optimizes oil palm mineral nutrition, with the whole plantation being brought to maximum yield at minimum cost (Optimum Economic Return).