-The rising demand for vegetable oil is inducing an expansion of oil palm cultivation in the tropics. In southern Cameroon oil palm smallholdings have been growing fast since the mid-1990s. Now, industrial plantations and smallholdings exist side by side. The current technical advice given to smallholders originates from agroindustrial practices. However, industrial plantations were created by planting on previous forest cover with no food intercrops, whereas for smallholdings food crops are a common previous cover and an intercrop during the juvenile phase. Technical advice used for industrial plantations may therefore not apply to smallholdings. Huge yield differences are observed in oil palm smallholdings, ranging from 2 to 14 t·ha −1 of fresh fruit bunches, while in industrial plantations yields average 14-16 t·ha −1 . As no agronomic evaluation to date had explained those variations, we carried out a regional agronomic diagnosis of N and K nutrition on smallholder plots planted with selected oil palms. To prepare leaf samples and determine mineral contents, we used the same standardised method and the same laboratory as the regional industrial plantations. We compared smallholder leaf N and K contents with reference models of critical mineral contents, previously built with data from the high-yielding industrial plantations. Statistical links were also established between nutritional status and practices. Our results showed two groups of oil palm plantations: a group with N deficiencies ranging between 80 and 90% of the reference and K deficiencies ranging from 45 to 90% of the reference, and another group with satisfactory N and K status. The N deficiency was statistically linked to food cropping as the previous cover or as an intercrop, whilst K deficiency was qualitatively linked to an absence of K fertilisation. N deficiency is a specificity of oil palm smallholdings that had never been encountered in African industrial plantations. To conclude, the current technical advice given to smallholders is not well adapted. mineral nutrition / regional agronomic diagnosis / oil palm smallholdings / Elaeis guineensis / Cameroon / nitrogen / potassium / nutritional status trends in oil palm plantations

Based on the results of studies conducted in Ivory Coast and Cameroon, the article proposes an analysis of the family agriculture situation in the oil palm commodity chain, repositioning it within a context of sustainable development issues. At a time when production standards are back on the agenda with so-called ″voluntary commitment″ processes, through ″private standards″ to enable sustainable agriculture, the authors examines the outcome of the previous phases of family agriculture standardization by Estates and State-owned companies between 1960 and 1990, followed by privatization of the sector. The article shows that family agriculture possesses its own rationality which needs to be taken into consideration, if the stakes, over and above guaranteeing ″sustainable oil″, are indeed those of the impact that the palm oil sector has on ″sustainable development″. Starting from that point, the question is no longer: how can family agriculture take on board technical standards designed for other production models, but how can family agriculture take part in the compromises negotiated in the commodity chain in such a way that its logics and operating methods are considered when drawing up production choices? An analysis of surveys on oil palm-based cropping and farming systems makes it possible a) to specify the logics underlying production practices and to show their specificity, b) and reiterate the minimum conditions required in order for this agriculture, which is the major agriculture in some countries, to achieve the socio-economic reproduction level of the household and not only of the plot: access to capital and information, minimum land areas and prices, representation on negotiating bodies. 1 The term "outgrower" is used here to mean all "non-estate" plantations. It covers a diversity of producer types.

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