The cultivation of oil palm in Sri Lanka has long been a subject of intense public discussion. A prevalent concern is the belief that oil palm farming harms soil health, increases erosion, diminishes biodiversity in the understory, and negatively affects the environmental integrity of plantation areas. These issues are significant, as healthy soil is crucial for vital ecosystem services such as water regulation, nutrient cycling, biodiversity preservation, and sustainable agriculture practices. Therefore, it is essential that public policies and societal discussions are grounded in scientific research rather than in speculative or unfounded assumptions.
It is important to note that the establishment of oil palm in Sri Lanka has occurred without the deforestation of natural forests. Currently, oil palm covers approximately 10,400 hectares, primarily in the lowland wet zones, and is predominantly planted on previously degraded or marginal lands that were once used for rubber or tea cultivation. Thus, a fair scientific evaluation should compare oil palm to other plantation crops within similar agro-climatic settings, rather than contrasting it with natural forest ecosystems. This perspective invalidates claims that oil palm farming leads to significant deforestation in the context of Sri Lanka’s agricultural landscape.
The soil types in regions where oil palm is grown are mainly classified as Red Yellow Podzolic soils or Ultisols, which are characteristically acidic, highly weathered, and generally low in fertility. These soils typically have reduced organic carbon content and nutrient availability, as well as a low cation exchange capacity. Such attributes are not exclusive to oil palm plantations but are common across much of the lowland wet zone that has been under commercial cultivation for over a century. Therefore, it is misleading to attribute all soil-related challenges to oil palm alone. The critical inquiry should be whether oil palm results in more severe or distinctive soil degradation compared to tea, rubber, or coconut when grown under similar conditions. Current scientific data do not support a generalized assertion of greater degradation from oil palm cultivation. Soil issues are often linked more to land management practices than specific crops, and these challenges can be largely alleviated through strategic soil and water conservation techniques.
Another prevalent misunderstanding is the notion that oil palm cultivation inherently leads to significant soil erosion. Erosion rates are influenced by various factors beyond the crop type, such as slope, rainfall intensity, soil coverage, and the presence of infrastructure like roads and drainage systems. Poorly managed plantations of any crop can contribute to erosion; for example, rubber can experience considerable soil loss during its initial growth phase if the soil remains uncovered. Conversely, with effective management, erosion can be minimized in rubber plantations, a principle that also applies to oil palm. Although Sri Lanka currently lacks extensive long-term data on soil erosion specifically for oil palm, existing international studies and local comparisons indicate that effective management practices can control erosion effectively. Techniques such as cover cropping, contour planting, terracing, mulching, appropriate drainage, frond stacking, and safeguarding steep slopes can mitigate runoff and preserve soil integrity. When implemented, these practices can prevent oil palm plantations from becoming susceptible to erosion.
Managing organic matter effectively is one of the significant opportunities in oil palm cultivation. The crop generates substantial biomass, including pruned fronds and empty fruit bunches that can be repurposed as mulch and organic matter. Empty fruit bunches are rich in essential nutrients such as nitrogen, phosphorus, potassium, and magnesium. Returning these materials to the fields enhances soil organic carbon levels, nutrient cycling, moisture retention, soil structure, and microbial activity. This is particularly crucial since other plantation systems often have limited sources of organic matter. For instance, in tea cultivation, prunings are often removed for fuelwood, while in coconut and rubber, trunks and husks are repurposed economically. In contrast, empty fruit bunches from oil palm have minimal alternative economic uses in Sri Lanka, making their return to the soil both practical and ecologically beneficial. Furthermore, these byproducts can also be transformed into high-quality compost and biochar, leading to wide-ranging advantages.
Soil acidification is a common challenge faced by agricultural fields in the wet zone, exacerbated by the application of nitrogen fertilizers through microbial action. This issue is well-documented in tea plantations, where the use of dolomite is recommended to counteract soil acidity. Research indicates no significant difference in soil acidity levels between oil palm and rubber plantations. However, soil acidification in oil palm fields can be managed or prevented through improved practices, such as applying empty fruit bunches or bunch ash and leaving fronds on the ground.
A widely held belief that oil palm requires excessive chemical fertilizers compared to other plantation crops is not entirely accurate. Scientific assessments present a more nuanced view; while oil palm generally requires higher fertilizer inputs than rubber on a per-area basis, its needs are comparable to those of coconut and lower than those of tea, especially regarding macronutrients like nitrogen. Tea has a notably higher nitrogen requirement, while coconut has a significant potassium requirement. Therefore, the assertion that oil palm uses several times more fertilizer than all other plantation crops is not substantiated by existing data. Additionally, it is critical to evaluate fertilizer usage not only by the total quantity applied but also by the agricultural output achieved per nutrient unit. When measured this way, oil palm demonstrates superior performance compared to tea, rubber, and coconut, achieving the highest yield per nutrient applied. These results indicate that with optimal management, oil palm can achieve high nutrient efficiency, maximizing crop yield relative to fertilizer inputs while minimizing environmental pollution through reduced nutrient loss via volatilization, leaching, and runoff. This is a vital aspect of sustainable agricultural practices.
Moreover, the claim that “nothing thrives under oil palm” lacks empirical support. Studies comparing understory vegetation in oil palm and rubber plantations of varying ages at Nakiyadeniya and Sapumalkanda estates found similar diversity levels, primarily comprising shade-tolerant and moisture-loving species. Additionally, some research has indicated that oil palm plantations may host higher earthworm populations compared to corresponding rubber areas. These findings challenge the prevailing notion that oil palm plantations are devoid of ecological value. However, in commercial practices, overgrown understory vegetation is generally regarded as weeds, leading plantation management to suppress these species through regular cutting or herbicide applications. Thus, the diversity and density of existing species are largely contingent upon specific management approaches. Intercropping practices can also be adopted in oil palm systems during both the immature phase (up to 3–5 years) and later stages of the cropping cycle. If diversification of products is the goal, continuous intercropping throughout the oil palm’s life cycle is feasible with appropriate adjustments in planting density and spatial arrangement.
Concerns have also been raised about the high water consumption associated with oil palm cultivation, which is said to deplete wells and waterways in the area. However, there is currently no scientific evidence to validate this assertion. A crop’s water requirements depend on various factors, including its variety, age, soil type, and environmental conditions. Estimates suggest that oil palm, coconut, and rubber require an average of 249, 130, and 63 liters of water per plant daily, respectively. Studies conducted at Nakiyadeniya and Sapumalkanda estates reported similar water usage rates under local conditions. Rather than assessing water consumption on an individual plant basis, it is more relevant to evaluate it per hectare. With a planting density of approximately 140 oil palm plants per hectare and 520 for rubber, the potential daily water use is around 34,480 liters for oil palm and 32,760 liters for rubber. Given these water needs, oil palm is best suited for regions that receive over 2,500 mm of rainfall each year, with about 150 to 200 wet days annually, during which the trees absorb minimal water. Consequently, oil palms utilize less than 35% of the total annual rainfall per unit area, indicating that water availability is not a limiting factor.
Additionally, the issue of waste generation during oil palm processing has been addressed through the modernization of facilities with advanced technologies, aiming for zero waste. This is exemplified by the AEN palm oil extracting and processing factory in Baduraliya, a collaboration of several plantation companies.
Overall, the scientific consensus is clear: oil palm cultivation is not inherently harmful to soil, does not diminish understory vegetation or biodiversity, and does not create water scarcity compared to other plantation crops. Environmental issues can arise from poorly managed oil palm, just as they can with tea, rubber, or coconut. However, when managed effectively, oil palm can contribute to soil conservation, nutrient recycling, organic matter enhancement, and sustained productivity. The discourse surrounding oil palm should shift from myths to measurable sustainability standards.
To address ongoing environmental and social challenges, it is recommended to pursue Roundtable on Sustainable Palm Oil (RSPO) certification. The RSPO framework establishes and verifies stringent global standards for sustainable production. Attaining this certification would provide consumers with assurance that palm oil is sourced ethically, without contributing to deforestation, harming wildlife habitats, or violating human rights, while also supporting biodiversity conservation. Several plantation companies have already acquired and maintained RSPO certification.
Regardless of the crop being cultivated, Sri Lanka necessitates a responsible, science-based framework for evaluating agricultural impacts. This initiative should incorporate localized research on key soil parameters, including erosion dynamics, organic carbon levels, water infiltration, nutrient pathways, and biological diversity. Furthermore, it should enforce best management practices that require growers, particularly in the perennial plantation sector, to implement cover cropping, residue recycling, slope protection, targeted fertilizer application, and systematic soil monitoring.
In conclusion, oil palm should neither be promoted uncritically nor condemned without justification. It must be evaluated scientifically, managed responsibly, and regulated appropriately. When guided by evidence and sound agricultural practices, oil palm can play a vital role in enhancing the productivity and sustainability of Sri Lanka’s plantation sector.
By Dr. S.P. Nissanka (BSc Agric [Peradeniya, Sri Lanka], MSc & PhD [Guelph, Canada])
Emeritus Professor, Faculty of Agriculture, University of Peradeniya.
Fellow of the National Academy of Sciences in Sri Lanka (NASSL)
Professional Fellow of the Sri Lanka Institute of Agriculture (FSLIAg)
General Secretary, Sri Lanka Institute of Agriculture.
Member of the UNDP-GEF-SGP National Steering Committee
Financial Chronicle Biz English | Sri Lanka Business News.
