Oil palm cultivation in Sri Lanka has for many years been surrounded by strong public debate. Among the most common allegations is that oil palm degrade soil, accelerates erosion, loss of understory biodiversity and weakens the environmental health of plantation landscapes. These concerns must not be dismissed lightly, because soil functions as the vital matrix sustaining essential ecosystem services including hydrological regulation, nutrient cycling, biodiversity conservation, and long-term agronomic sustainability. Consequently, public policy and social discourse must be informed strictly by scientific evidence rather than speculative, unsubstantiated preconceptions.
Crucially, oil palm establishment in Sri Lanka has been executed entirely without the conversion of natural forests. Currently, it occupies around 10,400 hectares, only in the wet zone low country, mainly on degraded or marginal lands previously cultivated with rubber or tea. Therefore, the appropriate scientific comparison lies between oil palm and co-existing plantation crops under similar agro-climatic conditions, rather than between oil palm and natural forest systems. Consequently, the allegation that oil palm cultivation drives extensive deforestation is invalid within the specific context of Sri Lanka’s agricultural landscape.
The soils found in these oil palm growing regions are largely Red Yellow Podzolic soils, classified as Ultisols. These soils are naturally acidic, highly weathered and relatively poor in fertility. They are commonly low in organic carbon, low in available nutrients and also having low cation exchange capacity. These characteristics are not unique to oil palm plantations. They are inherent to much of the wet zone low country plantation landscape, which has been under commercial plantation agriculture for more than a century. Therefore, attributing all regional soil related limitations to oil palm is misleading. The essential question is whether oil palm causes greater or more unusual soil degradation than tea, rubber, or coconut under similar conditions. The available scientific evidence does not substantiate such a generalized conclusion. Importantly soil related problems are not crop-specific, rather, it is primarily a function of land management practices, which can be significantly mitigated by implementing targeted soil and water conservation measures.
Another major misconception is the frequent assertion that oil palm cultivation inherently accelerates severe soil erosion. However, erosion rates are dictated by multiple variables beyond the crop itself, including terrain slope, rainfall intensity, soil cover, and infrastructure dynamics such as road construction, drainage networks, harvesting paths, and estate-level conservation practices. In poorly managed plantations, any crop can contribute to erosion. Rubber, for example, can show high soil loss during the early establishment phase if the soil is left exposed. Yet, in well-managed rubber plantations, erosion can be reduced to very low levels. The same principle applies to oil palm as well. Sri Lanka currently lacks sufficient long-term field data on soil erosion specifically under oil palm. However, available international evidence and local comparisons suggest that soil erosion under oil palm can be controlled effectively through good management. Cover crops, contour planting, terracing where needed, mulching, proper drainage, frond stacking and the protection of steep slopes are practical methods that reduce run-off and protect soil. When these practices are followed, oil palm plantations need not become erosion-prone landscapes.
Organic matter management is one of the strongest opportunities in oil palm cultivation. Oil palm produces a large volume of biomass, including pruned fronds and empty fruit bunches from processing factories. These materials can be returned to the field as mulch and organic matter. Empty fruit bunches contain valuable nutrients such as nitrogen, phosphorus, potassium and magnesium. Returning them to the plantation improves soil organic carbon, nutrient cycling, moisture retention, soil structure and microbial activity. This is particularly important because organic matter sources are often limited in other plantation systems. In tea, pruning’s are sometimes removed for fuelwood, while in coconut and rubber, trunks and husks are used for other economic purposes. In contrast, oil palm empty fruit bunches currently have limited alternative economic value in Sri Lanka, making their return to the soil both practical and environmentally sound. Alternatively, these materials can be effectively converted into high-quality compost and biochar, yielding wide-ranging benefits. Also, another important advantage of oil palm cultivation is its potential for organic matter management. Pruned fronds and biomass such as empty fruit bunches generated from processing factories can be returned to the cultivation land.
Soil acidification is a common problem in agricultural fields in the wet zone. Application of nitrogen fertilizers aggravates soil acidity further through microbial activities. This problem is well documented in tea plantations, where the recommended quantities of dolomite are applied to neutralize soil acidity. Studies indicate no significant difference in soil acidity between oil palm and rubber fields. However, in oil palm plantations, soil acidification can be mitigated or prevented by introducing better management measures such as applying empty fruit bunches or bunch ash, as well as by leaving fronds in the field.
It is a widely repeated myth that oil palm demands excessive chemical fertilizer compared with all other plantation crops. Scientific comparison shows a more balanced picture. On a per-unit-area basis, oil palm generally demands higher fertilizer inputs than rubber; however, its requirements are comparable to those of coconut and remain lower than those of tea for macronutrients, most notably nitrogen. Tea has a higher nitrogen requirement, while coconut has a very high potassium requirement. Therefore, the claim that oil palm uses several times more fertilizer than all other plantation crops is not supported by the available evidence. More importantly, fertilizer use must be assessed not merely by the gross quantity applied, but by agricultural productivity achieved per unit of nutrient.
On this measure, oil palm exhibits superior performance when compared to other plantation crops of tea, rubber, and coconut. Oil palm records the highest yield per unit of nutrient applied. These findings demonstrate that optimal management enables oil palm to achieve superior nutrient use efficiency and maximizing crop yield relative to fertilizer inputs while mitigating environmental pollution by reducing nutrient losses through volatilization, leaching, and runoff. This is an important factor in sustainable plantation agriculture.
Similarly, the claim that ‘nothing grows under oil palm’ is also not supported by evidence. Comparative studies of oil palm and rubber understory vegetation across different age categories at the Nakiyadeniya and Sapumalkanda estates revealed comparable diversity, consisting predominantly of shade-tolerant and moisture-loving species. Furthermore, certain studies have reported higher earthworm population densities within oil palm plantations compared to comparable rubber stands. Collectively, these findings challenge the conventional notion that oil palm plantations function as ecological deserts. However, in commercial practice, overgrown understory vegetation is typically classified as weeds. Plantation management routinely suppresses these species below an economic threshold through frequent manual slashing or herbicide applications; consequently, the existing species diversity and density are highly dependent upon estate-specific management strategies. Similar to practices in coconut and rubber cultivation, intercropping can be implemented in oil palm systems as well during both the immature phase (up to 3–5 years) and the later stages of the cropping cycle. Furthermore, if product diversification is the primary objective, continuous intercropping throughout the entire life cycle is achievable by adjusting the planting density and spatial field arrangement of the overstory oil palm crop.
Another critical concern involves the high volume of water consumed by oil palm, which allegedly dries out wells and waterways in cultivation regions; however, there is currently no scientific evidence to support this claim. A crop’s water requirement depends on its variety, age, soil type, and prevailing environmental conditions. The average daily water requirements for oil palm, coconut, and rubber are estimated at 249, 130, and 63 liters per plant, respectively. Furthermore, water consumption studies conducted at the Nakiyadeniya and Sapumalkanda estates reported similar usage rates under local conditions. However, rather than comparing water use on an individual tree basis, it is more statistically relevant to assess consumption per hectare. Given a planting density of approximately 140 plants per hectare for oil palm and 520 for rubber, the potential daily water usage scales to roughly 34,480 liters for oil palm and 32,760 liters for rubber. Due to these high water requirements, oil palm is only recommended for regions that receive more than 2,500 mm of rain annually. Given that these regions have about 150 to 200 wet days a year, during which the trees absorb very little water. Consequently, oil palms consume less than 35% of the total annual rainfall received per unit area, indicating that water availability does not become a limiting factor.
Furthermore, concerns regarding waste generation during manufacturing have been addressed by upgrading facilities with advanced technologies to achieve zero-waste generation. This is evident at the AEN palm oil extracting and processing factory operating in Baduraliya (a joint venture of Agalawatta, Elpitiya & Namunukula Plantations.
The overarching scientific consensus is definitive: oil palm is not inherently destructive to soil, not depleting understory vegetation and biodiversity, and also not causing water limitation compared to other plantation crops. Poorly managed oil palm can cause environmental problems, just as poorly managed tea, rubber or coconut can. But well-managed oil palm can conserve soil, recycle nutrients, improve organic matter and maintain productivity. The debate must therefore move away from myths and towards measurable sustainability standards.
In order to mitigate ongoing environmental and social impacts, it is proposed to obtain Roundtable on Sustainable Palm Oil (RSPO) certification. The RSPO framework establishes and verifies rigorous global standards for sustainable production. By achieving this certification, it can assure consumers that palm oil is harvested ethically: without causing deforestation, destroying wildlife habitats, or violating human rights, while continuously supporting biodiversity conservation. Several plantation companies have already obtained and maintaining the RSPO certification.
Regardless of the specific crop under cultivation, Sri Lanka needs a responsible, science-driven framework to evaluate agricultural impacts. This initiative should integrate localized research on core soil parameters including erosion dynamics, organic carbon, water infiltration, nutrient pathways, and biological diversity. Furthermore, it should incorporate mandatory best management practices that compel growers, especially within the perennial plantation sector, to adopt cover cropping, residue recycling, slope protection, targeted fertilizer application, and systematic soil monitoring.
Thus, Oil palm should neither be promoted blindly nor condemned unfairly. It should be assessed scientifically, managed responsibly and regulated properly. When guided by evidence and good agricultural practice, oil palm can be part of a more productive and sustainable plantation sector in Sri Lanka.
