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Predicting the fertilizer requirements of an oil palm plantation has long been a difficult task. Two main methods have emerged. Leaf analyses (LA) were used for fertilization management as early as the 1950s. Leaf contents are compared to optimum references, making it possible to adjust the fertilizer rates applied in each block. Another approach, based on the nutrient balance (NB), is to evaluate and replace nutrients that are exported from the field, or immobilized by the plant. Plantations must adopt environmentally friendly practices; in particular, fertilizer inputs must be estimated with sufficient precision to achieve the highest possible yields, without applying excessive amounts of nutrients in relation to plant demand and the storage capacity of soils. We questioned the relevance of each method for achieving these objectives. We did so using some long-term fertilization trials to compare the optimum N and K rates recommended by each method in the adult phase. It appeared that LA led to moderate rates compared to NB. It also appeared that calculating a precise nutrient balance on a field scale was hampered by a lack of precise information (i) about the biomasses produced and their composition and (ii) about the highly variable outputs of the environmental losses. On the other hand, LA provided a simple indicator of the ability for each block to achieve its potential yield. We believe that this perfectible method is more protective of the environment, without the risk of a significant decrease in yields or a decrease in soil mineral reserves.

The bud rot disease is the main threat to the palm oil industry in Ecuador. In the oil palm production area of Quevedo we evaluated smallholders' sensitivity to the risk of bud rot disease, through interviews conducted with 64 oil palm growers. They showed that only 9% of them implemented preventive measures and 17% adopted curative measures. Only 27% of farmers were aware of the disease and control measures. We used a spatialized typology of smallholdings to identify areas that would be the most sensitive to bud rot. The Northwest of the production area was considered as very sensitive because of a high percentage of family farm smallholdings with old plots managed extensively and with poor phytosanitary control. In contrast, the south of the production area was considered less exposed to the bud rot disease as it comprised mostly of holdings well managed and oil palm growers were well aware of the bud rot disease, with a more intensive management and a regular phytosanitary control. [ABSTRACT FROM AUTHOR]

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Oil palm is widely cultivated in Indonesia and it is produced by various populations of smallholders. Among those, ex-plasma smallholders are characterized by the fact that they only start to manage their own plantations 5 to 10 years after those were initially planted and managed by a partner industrial company. Despite the large areas that are cultivated by ex-plasma smallholders, their diversity of practices and economic performances are poorly quantified. The present study aims at investigating which smallholder farming systems optimize profitability at the plot scale. We defined two typologies, one based on agricultural practices and the other based on economic performance, using multivariate statistical analysis. The typologies were crossed to understand the links between agricultural practices and economic performance at the plot level. Our results showed that despite initial plot homogeneity during planting phase, ex-plasma smallholders can develop very diversified management practices. A gradient of intensification was observed from farmers implementing no fertilization or weeding management up to farmers following agroindustrial-like management. Economic performances at the plot level was found to be variable, with gross margins ranging from 1.1 to 26.9 M IDR.ha−1.yr−1 (eq. 66.4 to 1625.5€). We showed that the most intensive practices led to highest yields although these were not linked to the optimal economic plot performances. A trade-off based on input costs was revealed, as high fertilization practices did not seem economically optimal for smallholders. The present study highlights the need to combine quantified agronomic assessments with economic analysis, to properly design recommendations to farmers. [Display omitted] • The diversity of oil palm smallholders management practice and their performances remain poorly known. • We aim to understand which farming systems optimize the economic performance of oil palm. • A first typology on agricultural practices revealed a gradient of intensification, a second on economic performances revealed an optimum. • Crossing the two typologies showed that intensive practices are not economically optimal. • The study recommends to adapt local recommendations using multicriteria approaches. [ABSTRACT FROM AUTHOR]

Smallholders play a considerable role in oil palm production in Indonesia. Their specific constraints lead to contrasted plot management, especially for fertilization and understory vegetation. Studies disentangling the agro-environmental impacts of oil palm smallholders' management practices at the plot scale remain scarce. The extent to which smallholders' practices affect both agronomic and environmental performances is still to be investigated with robust in-field studies to provide improvement tracks. This study aimed at investigating the effects of both fertilization and understory vegetation management on soil health and oil palm performances. It explored a gradient of management practices, within homogeneous soil and climate conditions and historical development. The objective was to isolate and decipher the specific effects of some key practices on the overall plantation performances. We surveyed 16 ex-plasma oil palm smallholders' 25-year old plots, gathering detailed information on management and implementing field measurements (48 points). For soil health assessment, we applied Biofunctool® that consists of nine in-site indicators informing on the soil ability to transform carbon, recycle nutrient and maintain its structure. For the oil palm performances, we relied on conventional appraisal parameters, such as yields, leaf area and nutrient leaf analyses. Our results highlighted that fertilization, especially potassium, played a significant role in sustaining oil palm performances. Understory vegetation had a direct and positive effect on soil structure maintenance indicators. Soil structure improvement was correlated with enhanced oil palm performances. Those results highlighted that, besides nutritional aspects, increasing plot biodiversity through understory vegetation maintenance was associated with enhanced soil health hence potential greater ecosystem functions. The findings have implications in terms of better understanding the effects of combined farming practices on the soil-oil palm continuum. It especially highlighted the key role of understory vegetation to improve soil structure maintenance without competing with oil palms in the studied context. [Display omitted] • Oil palm smallholders implement diverse management practices. • We studied the effects of practices on soil health and oil palm performances. • K fertilization is a driver for oil palm performances and understory vegetation improved soil health. • Besides plant nutrition considerations, increasing biodiversity with understory may enhance ecosystem functions. • These results highlight the importance of understory vegetation in oil palm plantation and could help technical guidances. [ABSTRACT FROM AUTHOR]