Oil Palm Expansion Research Articles

Slowing deforestation in Indonesia follows declining oil palm expansion and lower oil prices

Much concern about tropical deforestation focuses on oil palm plantations, but their impacts remain poorly quantified. Using nation-wide interpretation of satellite imagery, and sample-based error calibration, we estimated the impact of large-scale (industrial) and smallholder oil palm plantations on natural old-growth ("primary") forests from 2001 to 2019 in Indonesia, the world's largest palm oil producer. Over nineteen years, the area mapped under oil palm doubled, reaching 16.24 Mha in 2019 (64% industrial; 36% smallholder), more than the official estimates of 14.72 Mha. The forest area declined by 11% (9.79 Mha), including 32% (3.09 Mha) ultimately converted into oil palm, and 29% (2.85 Mha) cleared and converted in the same year. Industrial plantations replaced more forest than detected smallholder plantings (2.13 Mha vs 0.72 Mha). New plantations peaked in 2009 and 2012 and declined thereafter. Expansion of industrial plantations and forest loss were correlated with palm oil prices. A price decline of 1% was associated with a 1.08% decrease in new industrial plantations and with a 0.68% decrease of forest loss. Deforestation fell below pre-2004 levels in 2017-2019 providing an opportunity to focus on sustainable management. As the price of palm oil has doubled since the start of the COVID-19 pandemic, effective regulation is key to minimising future forest conversion.

Multispecies mourning: grieving as resistance on the West Papuan plantation frontier

ABSTRACT This article explores the cultural, political, and affective significance of mourning among the Indigenous Marind communities of rural Merauke West Papua, whose intimate and ancestral relations to native plants, animals, and ecosystems are increasingly threatened by mass deforestation and monocrop oil palm expansion. Cross-pollinating Indigenous more-than-human philosophies with environmental humanities scholarship, I examine three emergent practices of ‘multispecies mourning’ on the Papuan oil palm frontier – the weaving of sago bags as a form of collective healing, the creation of songs prompted by encounters with roadkill, and the transplanting of bamboo shoots as part of customary land reclaiming activities. Multispecies mourning offers potent avenues for Marind to memorialize the radical loss of lives and relations prompted by capitalist landscape transformations. At the same time, multispecies mournings constitute forms of active resistance and creative refusal in the face of extractive capitalism’s ecocidal logic. Bringing together plants, people, and places, their dispersed sentience and materiality offer hopeful pathways for multispecies solidarities, in and against the rubble of agro-industrialism and its necropolitical undergirdings.

Oil palm expansion increases the vectorial capacity of dengue vectors in Malaysian Borneo.

Changes in land-use and the associated shifts in environmental conditions can have large effects on the transmission and emergence of mosquito-borne disease. Mosquito-borne disease are particularly sensitive to these changes because mosquito growth, reproduction, survival and susceptibility to infection are all thermally sensitive traits, and land use change dramatically alters local microclimate. Predicting disease transmission under environmental change is increasingly critical for targeting mosquito-borne disease control and for identifying hotspots of disease emergence. Mechanistic models offer a powerful tool for improving these predictions. However, these approaches are limited by the quality and scale of temperature data and the thermal response curves that underlie predictions. Here, we used fine-scale temperature monitoring and a combination of empirical, laboratory and temperature-dependent estimates to estimate the vectorial capacity of Aedes albopictus mosquitoes across a tropical forest-oil palm plantation conversion gradient in Malaysian Borneo. We found that fine-scale differences in temperature between logged forest and oil palm plantation sites were not sufficient to produce differences in temperature-dependent demographic trait estimates using published thermal performance curves. However, when measured under field conditions a key parameter, adult abundance, differed significantly between land-use types, resulting in estimates of vectorial capacity that were 1.5 times higher in plantations than in forests. The prediction that oil palm plantations would support mosquito populations with higher vectorial capacity was robust to uncertainties in our adult survival estimates. These results provide a mechanistic basis for understanding the effects of forest conversion to agriculture on mosquito-borne disease risk, and a framework for interpreting emergent relationships between land-use and disease transmission. As the burden of Ae. albopictus-vectored diseases, such as dengue virus, increases globally and rising demand for palm oil products drives continued expansion of plantations, these findings have important implications for conservation, land management and public health policy at the global scale.

Spatial patterns and drivers of smallholder oil palm expansion within peat swamp forests of Riau, Indonesia

Protecting the tropical peat swamp forests in Southeast Asia is critical for addressing global sustainability challenges such as climate change and biodiversity loss. However, more than half of these forests have been lost since 1990 due to the rapid expansion of drainage-based agriculture and forestry. Within the oil palm sector, the number of regional smallholder oil palm plantings on peat soils has risen quickly. These activities are challenging to govern and manage, due to their fragmented nature and the numerous farmers involved. It is imperative to understand the spatial distribution and drivers of the smallholder oil palm-related conversion of peat swamp forests. In contrast to existing studies based on farm surveys, we used state-of-art maps of smallholder oil palm plantings, derived from 2019 remote sensing data. Spatial data about socioeconomic and biophysical factors (e.g. mills, roads, water ways, and concessions) was then used to develop logistic regression models to investigate the relative influence of these factors. We show that the spatial patterns of smallholder oil palm plantings are distinct from those of industrial oil palm plantations, revealing the critical roles of roads, especially service roads, residential roads and tracks, in driving smallholder oil palm expansion within peatlands. We found that 90% of smallholder oil palm areas were located within 2 km of roads and 25 km of mills. The mean likelihood of a given land area being converted from peat swamp forests to smallholder oil palm declined rapidly with increasing distance from roads and mills. In addition to roads and mills, land use zones (e.g. the setting of concessions and migration settlements) and other environmental factors (e.g. precipitation and elevation) were identified as important drivers of smallholder oil palm expansion on peatland. Based on these findings, we identify priority regions for the protection of the remaining peat swamp forests in Indonesia and discuss strategies for tackling these sustainability challenges on local and global scales.

Anti-Corporate Activism and Collusion: The Contentious Politics of Palm Oil Expansion in Indonesia

The rapid expansion of oil palm plantations in Indonesia has generated a large and growing number of protests against palm oil companies over, mainly, access to land. So far, these protests have been mainly studied through scattered case studies, which precludes an understanding and analysis of general patterns. Addressing this challenge, this paper presents the results of the first-ever large-scale collaborative effort to document 150 conflicts between rural Indonesians and palm oil companies in four Indonesian provinces (West Kalimantan, Central Kalimantan, Riau and West Sumatra). With this material this article unpacks trajectories of the anti-corporate activism sparked by the rapid expansion of palm oil plantations, discussing the causes, character of protests, conflict resolution efforts and outcomes of these conflicts. We find that palm oil conflicts generate a particular ‘rightless’ form of collective action: instead of invoking legal provisions or rights, communities often avoid formal institutions while adopting largely accommodative forms of protest aimed at improving their bargaining position vis-à-vis companies. Despite regular and intense protests often directed at local governments, we find that in 68 percent of the studied conflicts communities fail to address their grievances. We argue that this limited success is not just due to the inadequacies of legal frameworks but also to the way in which Indonesia’s informalized state institutions foster collusion between powerholders and palm oil companies. Such collusion has facilitated the repression of protests and undermined the effectiveness of conflict resolution mechanisms.

Oil palm and gendered time use: A mixed-methods case study from West Kalimantan, Indonesia

Measuring the social impact of oil palm requires the use of multiple metrics which capture different dimensions of well-being. To date, most studies have examined welfare outcomes at the household level, relying on a relatively narrow range of indicators. There is a need for a more diverse range of metrics to measure the social impacts of oil palm as well as more explicit accounting for study context and gendered effects. Here we demonstrate the utility of specialised time use methods used in combination with qualitative research to understand intra-household labour dynamics associated with oil palm adoption. We use a mixed-methods approach to investigate the role of smallholder oil palm plasma schemes on men and women's time use in Kapuas Hulu District, West Kalimantan. Time allocation is an important determinant of well-being as well as maternal and child nutrition and an indicator of women's empowerment and gender equality. We integrate the results from a fractional multinomial logistic regression of data from 603 individuals with qualitative findings on the subjective experience of time allocation, as well as, the causes, consequences and coping strategies to manage trade-offs in time allocation. We find that relative to non-oil-palm adopting swidden farmers, participation in oil palm plasma schemes is associated with more time spent in productive labour for both men and women, driven by off-farm labour on oil palm plantations. For women, increased time comes at the cost of reduced time spent in rest, leisure and sleep. Increased time spent in off-farm labour drives households to adapt agricultural production methods, changing cash crop production as well as accelerating swidden transitions. These changes alter gender dynamics and responsibilities within the household. Our results suggest that changes in time allocation may have significant consequences for women's well-being and gender equity. Women in the oil palm site experienced greater stress over time scarcity and employed coping strategies more frequently. Our findings indicate that time allocation could be used as an indicator of the effects of oil palm expansion and adoption on well-being and that potential effects of time scarcity on well-being, gender equity, and maternal and child nutrition should be considered by policy makers when making land use decisions.

Deforestation-free land-use change and organic matter-centered management improve the C footprint of oil palm expansion.

In recent decades, mounting evidence has indicated that the expansion of oil palm (OP) plantations at the expense of tropical forest has had a far pernicious effect on ecosystem aspects. While various deforestation‐free strategies have been proposed to enhance OP sustainability, field‐based evidence still need to be consolidated, in particular with respect to savanna regions where OP expansion has recently occurred and that present large area with potential for OP cultivation. Here we show that the common management practice creating within the plantation the so‐called management zones explained nearly five times more variability of soil biogeochemical properties than the savanna land‐use change per se. We also found that clayey‐soil savanna conversion into OP increased total ecosystem C stocks by 40 ± 13 Mg C ha−1 during a full OP cultivation cycle, which was due to the higher OP‐derived C accumulated in the biomass and in the soil as compared to the loss of savanna‐derived C. In addition, application of organic residues in specific management zones enhanced the accumulation of soil organic carbon by up to 1.9 Mg ha−1 year−1 over the full cycle. Within plantation, zones subjected to organic amendments sustained similar soil microbial activity as in neighboring savannas. Our findings represent an empirical proof‐of‐concept that the conversion of non‐forested land in parallel with organic matter‐oriented management strategies can enhance OP agroecosystems C sink capacity while promoting microbe‐mediated soil functioning. Nonetheless, savannas are unique and threatened ecosystems that support a vast biodiversity. Therefore, we suggest to give priority attention to conservation of natural savannas and direct more research toward the impacts of the conversion and subsequent management of degraded savannas.

Quantifying oil palm expansion in Southeast Asia from 2000 to 2015: A data fusion approach

ABSTRACT The fusion of optical imagery with radar data can provide more accurate land cover change analysis of deforestation and tree-based agriculture. Radar data is limited temporally with most geographic areas not covered prior to 2007. This paper presents a new methodology to classify land cover change related to oil palm expansion that takes historic data limitations into account. Our approach utilizes Hansen’s Global Forest Cover data, optical imagery, and texture information, to extract land cover information in Sumatra and Western Malaysia, where historical data is absent. Our method demonstrates how to accurately classify oil palm without radar data with overall accuracies for optical only experiments within 4.4% of optical plus radar classifications. Our results show agricultural land use was the primary driver of land cover change with the largest increase due to oil palm expansion (6.1%). Better estimations of oil palm expansion could be used in sustainable land management policies.

Organic farming enhances soil carbon and nitrogen dynamics in oil palm crops from Southeast Amazon

ABSTRACT The expansion of oil palm (Elaeis guineensis Jacq, Arecaceae) crops threatens tropical rainforests. It negatively impacts a series of ecosystem services and functions, including carbon (C) sequestration and dynamics, as well as nutrient cycling. Such negative impacts have pressured companies to adopt conservationist practices in palm oil production. And yet the conversion from conventional to organic farming has gained space in the last decade, studies assessing the effects of organic oil palm crops on ecosystem functioning are still scarce. Here, we assessed how alternative farming practices affect organic matter dynamics in oil palm crops. We compared oil palm crops under conventional (CP) and organic (OP) farming in Southeast Amazon. We also sampled lowland dense ombrophilous forest (floresta densa de terra firme, FT) as reference. Soils were sampled at 0–10, 10–20, and 20–30 cm depth intervals to determine soil physical–chemical properties and C and nitrogen (N) concentrations and stocks. The highest soil C and N concentrations were found at 0–10 cm interval in CP and OP. We detected no variation in soil C and N stocks within depth intervals in FT and CP, while OP had higher soil C and N stocks at the 0–10 cm interval. When comparing OP and CP crops, soil C concentrations and stocks did not vary within zones or depth intervals. All OP zones had higher soil N concentrations and stocks than their conventional counterparts, and we found a variation within depth intervals. Our results show that organic farming has positively influenced organic matter dynamics. Organic oil palm crops preserved and even increased C and N sequestration.

Projecting Global Oil Palm Expansion Under Zero-Deforestation Commitments: Direct and Indirect Land Use Change Impacts

Projecting Global Oil Palm Expansion Under Zero-Deforestation Commitments: Direct and Indirect Land Use Change Impacts

Developing Multi-Source Indices to Discriminate between Native Tropical Forests, Oil Palm and Rubber Plantations in Indonesia

Over the last 18 years, Indonesia has experienced significant deforestation due to the expansion of oil palm and rubber plantations. Accurate land cover maps are essential for policymakers to track and manage land change to support sustainable forest management and investment decisions. An automatic digital processing (ADP) method is currently used to develop land cover change maps for Indonesia, based on optical imaging (Landsat). Such maps produce only forest and non-forest classes, and often oil palm and rubber plantations are misclassified as native forests. To improve accuracy of these land cover maps, this study developed oil palm and rubber plantation discrimination indices using the integration of Landsat-8 and synthetic aperture radar Sentinel-1 images. Sentinel-1 VH and VV difference (>7.5 dB) and VH backscatter intensity were used to discriminate oil palm plantations. A combination of Landsat-8 NDVI, NDMI with Sentinel-1 VV and VH were used to discriminate rubber plantations. The improved map produced four land cover classes: native forest, oil palm plantation, rubber plantation, and non-forest. High-resolution SPOT 6/7 imagery and ground truth data were used for validation of the new classified maps. The map had an overall accuracy of 92%; producer’s accuracy for all classes was higher than 90%, except for rubber (65%), and user’s accuracy was over 80% for all classes. These results demonstrate that indices developed from a combination of optical and radar images can improve our ability to discriminate between native forest and oil palm and rubber plantations in the tropics. The new mapping method will help to support Indonesia’s national forest monitoring system and inform monitoring of plantation expansion.

Species loss from land use of oil palm plantations in Thailand

Expansion of oil palm plantation areas in Thailand, the world's third-largest oil palm producer, for food and fuel may sometimes encroach on forest areas, leading to biodiversity loss. Thailand is in the Indo-Burma biodiversity hotspot, which contains high species richness. This study assesses the impacts of oil palm plantations on bird and insect species richness from land use in the five regions of Thailand by using the countryside Species-Area Relationship model. Data from the Global Biodiversity Information Facility (GBIF) and Thailand’s Land Development Department (LDD) were used for species occurrence and land use data, respectively. This study focuses on the deforestation for oil palm because it poses the highest risk for wildlife compared to other habitats. The taxon affinity and regional characterization factors show the risk to wildlife (birds and insects) in the formerly natural habitat areas (i.e., deciduous, evergreen, and mangrove forests). The results show that the possibility of animal survival in former mangrove forests is higher than in other forests upon occupation, as demonstrated by the taxon affinity. Likewise, deforestation in the northern region causes the least species loss per area, as demonstrated by the lowest average regional characterization factor, because species densities are lowest. However, the impacts on species richness depend on the taxon and the combination of the region and the forest type. While the overall goal should be to minimize the expansion of oil palm, this study indicates in which forest type and Thai region land occupation causes less regional bird and insect species loss.

Closing the Frontier, Opening Doors

In this article I examine a recent communal cocoa planting project in a Wide Bay Mengen community in East Pomio, Papua New Guinea in relation to histories of resource extraction. I discuss how the community members modeled the current planting of cocoa in accordance with earlier forms of agriculture, namely copra production and swidden horticulture. The cocoa planting project is linked to a longer history of labour and resource extraction in Pomio. I analyze the cycles of labour recruitment, logging, and oil palm expansion through the framework of the frontier, by which I mean a spatio-temporal process through which certain areas are portrayed as having abundant resources, which are made available for extraction. The cocoa planting project was a local response to these conditions and intended to be a source of income based on inalienated labour and local landholding and a spatial strategy of establishing points of access to other places, called 'doors' by the community members. My aim in this article is twofold. First, I argue that the frontier understood as a spatio-temporal process helps us to conceptualize cycles of resource extraction. Second, I show how people living in areas understood as frontiers form their own analyses and responses to the conditions under which their land, labour, and resources are made available to others.
 Keywords: cocoa, commodification, frontier, infrastructure, natural resources, oil palm, Papua New Guinea, place, territorialization

Oil palm expansion among non-industrial producers in Cameroon: Potentials for synergy between agro-economic gains and ecological safeguards

Regardless of the environmental and socio-ecological implications of oil palm cultivation, oil palm is considered one of the most important oil crops in the world because of its high production efficiency which has seen a marked increase in the area under cultivation. While previous studies have analyzed the implications of this increase in cultivation on various socio-economic and environmental indicators, less is known about the drivers and constraints of production, especially concerning economic and profitability motives. In this study, we used a survey of non-industrial producers in the humid rainforest zone of Cameroon to assess the drivers of oil palm production. We employ a double hurdle model in a two-step regression framework to characterize oil palm production by smallholder farmers, and the extent of oil palm production. For comparison purposes, a Tobit model is also estimated. We find that different socio-economic and institutional factors have a differential relationship with both the likelihood of cultivating oil palm and the area under oil palm cultivation. Key among these are expected profitability measures such as market orientation and access to market information, land tenure security, and access to improved farm inputs. Some aspects of transaction cost and labour availability also come into play in determining oil palm production. Across a range of different farm classifications related to the scale of production, we find that oil palm cultivation is prevalent among all farm groups, although highly predominant in large farms. We also show that our results are robust over several linear specifications such as the linear probability model and the lasso linear model. Our study thus provides evidence of several entry points for improving the oil palm sector for non-industrial producers while safeguarding the environment.

Water requirements for oil palm grown on marginal lands: A simulation approach

Oil palm is one of the most rapidly growing tree crops in the tropics. It is long-lasting and high yielding, serving as an input for a number of profitable industries. The rapid expansion of oil palm has triggered environmental change. Historically, the focus has been on the impact of biodiversity loss. However, the water requirements of oil palm plantations, which traditionally depended on rainfall only, are also changing, partly because environmental concerns are directing oil palm expansion and cultivation into marginal areas. According to some estimates, these lands with cultivable marginal soils— having an acid pyrite layer in the soil profile— comprise about 7.5 million ha in Indonesia. Here, we employed the Agricultural Production Systems sIMulator (APSIM) to simulate the growth of oil palm on marginal lands within Indonesia over an eight year period. APSIM-Oil palm was used to estimate the irrigation water requirement at different stages of plant growth for actual weather and soil conditions. Traditionally, water footprint accounting of oil palm plantations at the field level considers one uniform value of evapotranspiration. Our analysis shows that considering a single value for the entire period of oil palm growth underestimates the water requirement at the field scale. Annual irrigation needs were found to range from 2543 mm to 3865 mm for the plantation ages examined (0-8 years). We approximate that 8800 m3 of blue water and 6200 m3 of green water is required per ton of fresh fruit bunch produced from the study plantation occupying marginal lands, where water requirements were largely governed by maintenance of a high water table. Similarly high volumes are likely to be required where oil palm is cultivated on pyritic soils. Thus, the irrigation water requirement can no longer be neglected as oil palm plantations continue to expand onto marginal soils.

Land suitability assessment for oil palm plantations in Thailand

Oil palm plantations have been expanded in all regions of Thailand during the past decade to support the higher consumption of palm oil for food and fuel. It is, however, imperative to expand in those areas that have soil quality suitable for oil palm cultivation. Therefore, this study aimed to assess land suitability for the different regions of Thailand where oil palm is being cultivated. The suitability is justified by two aspects, viz., soil quality and remaining suitable areas. The Land Use Indicator Value Calculation in Life Cycle Assessment (LANCA®) method was used for the assessment. The results demonstrated that the soil quality in the southern region was most suitable for oil palm cultivation. Although this region has a lower availability of plantation areas as compared to the other regions, it is still enough to satisfy the forecasted oil palm expansion areas. Meanwhile, although the northeastern region ranked second in terms of appropriate soil quality, it may not be appropriate for oil palm due to the low groundwater regeneration. Hence, it is also important to look at the individual properties contributing to soil quality rather than deciding only on the basis of one aggregated indicator.

Scenarios for oil palm expansion in degraded and deforested lands in the Brazilian Amazon to meet biodiesel demand

Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.

Transformation and endurance of Indigenous hunting: Kadazandusun‐Murut bearded pig hunting practices amidst oil palm expansion and urbanization in Sabah, Malaysia

Abstract Land‐use change and political–economic shifts have shaped hunting patterns globally, even as traditional hunting practices endure across many local socio‐cultural contexts. The widespread expansion of oil palm cultivation, and associated urbanization, alters land‐use patterns, ecological processes, economic relationships, access to land and social practices. In particular, we focus on the socio‐ecological dynamics between Kadazandusun‐Murut (KDM) hunters in Sabah, Malaysian Borneo, and bearded pigs (Sus barbatus; Malay: ‘babi hutan’), the favoured game animal for non‐Muslim communities throughout much of Borneo. We conducted 38 semi‐structured interviews spanning over 50 hr with bearded pig hunters, asking them about contemporary hunting practices and motivations, changes in hunting practices, changes in pig behaviour, and patterns of animal protein consumption in village and urban contexts. Amidst widespread land‐use change, primarily driven by oil palm expansion, respondents reported substantially different characteristics of hunting in oil palm plantations as compared to hunting in forests. Additionally, 17 of 38 hunters—including 71% (10/14) of hunters who started hunting before 1985, compared to 26% (6/23) of hunters who started hunting in 1985 or later—mentioned that bearded pigs are behaving in a more skittish or fearful way as compared to the past. Our respondents also reported reductions in hunting frequency and wild meat consumption in urban contexts as compared to rural contexts. However, despite these substantial changes in hunting and dietary practices, numerous KDM hunting motivations, hunting techniques and socio‐cultural traditions have endured over the last several decades. For some, bearded pig meat remains deeply tied to food provision, gifting and sharing customs, and cultural components of celebrations and feasts. Oil palm has cultivated new hunting practices that differ from those in forests, and has potentially contributed to altered bearded pig behaviour due to increased hunting accessibility. Together, oil palm and urbanization are helping reshape the KDM‐bearded pig socio‐ecological system. In light of these reshaped connections, we recommend location‐specific management approaches that ensure fair access to the dietary and social benefits of bearded pig hunting while preserving the critical conservation needs of bearded pig populations and habitat. These twin goals are particularly urgent given the confirmed outbreak of African Swine Fever (ASF), and mass deaths of domestic pigs and wild bearded pigs, in Sabah and Kalimantan in 2021. A free Plain Language Summary can be found within the Supporting Information of this article.

Oil palm agroforestry shows higher soil permanganate oxidizable carbon than monoculture plantations in Eastern Amazonia

AbstractThe expansion of oil palm(Elaeis guineensisJacq.) cultivation in degraded areas has increased in the Brazilian Amazon. Cultivation of oil palm in diversified agroforestry systems may be a relatively sustainable alternative to monocultures for crop expansion. Here, we evaluated the effect of oil palm cultivation systems on soil C, an important indicator of the soil quality of production systems. We assessed: (1) whether these systems of oil palm cultivation alter the potassium permanganate oxidizable C content (POx‐C) and the carbon management index (CMI); and (2) how the POx‐C varied among management zones (harvest path, leaf pile, weeded circle, and diversified strip). The soil C indices of the oil palm cultivation systems were also compared with those of secondary forests. POx‐C varied consistently based on the pattern agroforestry > secondary forest = monoculture, ranging from 0.95 ± 0.14 (agroforestry) to 0.66 ± 0.10 g·kg−1(monoculture). The POx‐C pattern among management zones was pile > diversified strip = weeded circle > harvest path. The CMI was higher in agroforestry than in monoculture. We found that these indices are sensitive to land‐use systems and management practices that affect organic matter input. Organic fertilization and species diversity likely drive the improvement of soil quality in agroforestry systems than in monocultures through C input to the soil directly and indirectly, by creating favorable conditions for the action of root and fauna that in turn positively affect soil C. Therefore, we postulate that soil quality improves through oil palm agroforestry than through oil palm monocultures.

Improving economic and environmental outcomes in oil palm smallholdings: The relationship between mulching, soil properties and yields

CONTEXTThe area under oil palm cultivation has expanded importantly in South-East Asia. The resulting land-use transformations are associated with environmental degradation such as substantial carbon dioxide emissions. Soil conservation practices can contribute to more sustainable oil palm systems by increasing soil organic carbon (SOC) contents and yields. One soil conservation practice in oil palm plantations is the mulching with empty fruit bunches (EFB). OBJECTIVEWe estimated the relationship between EFB mulching and, respectively, yields, SOC and total nitrogen contents, the carbon‑nitrogen ratio and the average bulk density in smallholder oil palm plantations. We further analyzed the determinants of smallholders' EFB application taking into account regional market, farm, and plot level aspects, as well as farmers' perceptions. METHODSWe estimated the relationship between mulching and yields with panel data, and between mulching and soil properties with cross-sectional data. We accounted for the possible selection bias of the decision to apply EFB mulching with instrumental variable estimations. Descriptive analysis was used to analyze the determinants of smallholder EFB use. RESULTS AND CONCLUSIONSOur results indicated that in particular the regional supply in EFB and farmers' wealth levels were correlated with smallholder EFB mulching. EFB mulching was associated with 39% higher yields and 19% higher SOC contents. We attribute the higher yields to potentially improved soil chemical functions linked to higher SOC contents, such cation exchange capacity effects, and to an increased K and potentially Mg availability. Since EFB is not available in sufficient quantity to be applied to all plantations, policy makers could identify user groups with the greatest potentials for environmental and income improvements. Site-specific life cycle assessments and yield effects can help to inform such identification. SIGNIFICANCEDespite their growing importance in the oil palm sector, evidence on the effect of EFB mulching was missing for smallholder farmers. Because of associated higher SOC contents and yields, our findings indicate that the promotion of EFB mulching as best management practice could potentially contribute to more sustainable oil palm systems. Strengthening inclusive value chains for smallholders, information provision and investments in road infrastructure represent potential policy instruments to increase smallholder EFB application. The identification and promotion of best management practices are important with view to the still ongoing oil palm expansion in South-East Asia, and progressively in other parts of the world.