An Open Letter To The President: Does Oil Palm Deplete Soil Water Sources?
Oil palm
By Parakrama Waidyanatha –JULY 6, 2019
Dr. Parakrama Waidyanatha
An open letter to His Excellency the President; An Unscientific Report by the Central Environmental Authority on Oil Palm and Peoples’ Objection to its Cultivation
Your Excellency,
There was a news item in the press recently that some local politicians and villagers were objecting to the cultivation of oil palm in the Galigamuwa area, of the Kalutara district. Sadly, among other things, this is apparently a consequence of a highly unscientific report that had been produced under the aegis of the Central Environmental Authority (CEA), and the belief that this crop is causing drying of wells and streams. I believe you had the occasion to consider its contents. The scientists of the Coconut Research Institute, the organization that is vested with the conduct of research on oil palm and several other contributors to it had disagreed with much of the observations in the document and refused to sign it. Consequently, the report had been presented as several components written separately by the participating institutions.
The contention of the CEA is that it is not as environmentally friendly as tea, rubber and coconut and because of some other considerations too, it is not recommending its cultivation expansion. However, the Plantations Ministry in its component of the report states that it is no less environmentally friendly than the other plantation crops, and given also the massive economic importance of oil palm, it is seeking your approval as the Minister in charge of the subject of the environment to expand its cultivation. However, regrettably it would appear that your approval has hitherto not been forthcoming.
Does oil palm causes drying of wells and streams?
The main objection to the cultivation of oil palm by the CEA and several other environmentalists is its purported excessive consumption of water leading to drying of wells and streams. The CEA has based its arguments on the basis of per tree evapo-transpiration (ET) of rubber and oil palm. It has been pointed out that, whereas a mature rubber transpires only about 63 litres of water per day, an oil palm tree transpires 249 litres. However, scientifically ET should be measured on per unit area basis and not per plant. Whereas the recommended planting density of rubber is 520 trees per hectare that of oil palm is only 143 implying that the corresponding rates of ET should be 32,760 and 35,607 l/ha respectively; a difference of a mere 8.6%. Can such a small difference in ET cause such a vast impact on drying of water sources? The whole country (wet zone) has yet less than 10,000ha of oil palm and the proposal is merely to increase it to 20,000 ha. The increasing water consumption over the years with increasing population and global warming-related weather changes are perhaps the reason for the phenomenon. Even in non-oil palm cultivated areas of the wet zone instances of drying of streams and wells are not uncommon.
Other absurd observations in the Report
Of some 15 observations in the CEA report the large majority are baseless and some are howlers! That growing oil palm on slopes causes excessive erosion is one of them. Like rubber oil palm plants are established along contours in platforms and the soil is usually well protected with cover crops (see photo).
Young oil palm cultivation with a leguminous soil cover
Compared to tea where the average soil loss during land preparation for replanting is over 250 tons/ha, and soil loss continues through its life cycle, the losses with rubber and oil palm cultivation are comparatively small. It is also reported that oil palm causes soil compaction. This contention is not supported by research evidence in Sri Lanka, and is unlikely to be more than for rubber.
The Report also states that there is excessive use of pesticides and fertilizers in oil palm, the latter being 8-10 times that of rubber. These are also faulty. The use of pesticide is no greater than with other plantation crops and fertilizer use is only about double that of rubber. Being a highly productive crop high nutrient demand is to be expected like in tea.
