Environmental issues and plantation management

Dr. N. Yogaratnam Tree Crops Agro Consultants

With the liberalization of economic policies, the Government has also recognized the need to integrate environmental concerns with the development process and for the sustainable use of the natural resources, in order to address national as well as international environmental concerns.

Policy decisions tend to be guided by the concept that environmental conservation and development efforts are not in conflict, but are two sides of the same coin.

Efforts are therefore being directed towards finding the right balance between the needs of development and environmental protection.

One of the problems related to the low land productivity rate in the planation sector of Sri Lanka is the loss of fertile top soil through erosion and associated land degradation. Soil erosion has also caused major off-site environmental problems related to silting of reservoirs, with adverse effects on hydropower generation capacity and irrigation of agricultural land in the dry zone.

Another environmentally-related problem is the leeching away of fertilizer (nitrates) from steeply sloping land into downstream water bodies.

Environmental issues related to processing activities in the plantation sector also pose significant problems, except in the tea sector. In fact, tea related activities have been categorized as ‘low polluting’ by the Central Environmental Authority (CEA).

Nevertheless, all processing activities are monitored through the issuance of environment protection licences (EPLs) under which the national standards such as BOD, COD for effluent disposal, a major problem in the rubber, coconut and oil palm sectors, have been laid down by CEA .

With regard to international environmentally-related Conventions and other agreements affecting the tea sector, and to which Sri Lanka is a party, another issue that is being looked into is the use of methyl bromide as a soil fumigant. Its use in Sri Lanka is regulated and controlled under the Control of Pesticides Act.

Limitations and challenges

With the privatization of State plantations, the focus on environmental issues pertaining to the plantation sector, became somewhat complicated and challenging. It appears that these issues were not enforceable through contracts with the private sector at the time of privatization, for example, land-use issues related to environmental degradation.

Therefore, these issues may need to be addressed more through normal laws and regulations, while at the same time taking into account developmental needs. In that context, balancing enforcement measures with awareness and training through assistance programs appears to be a big challenge for the authorities.

Soil erosion and degradation

During the past five decades, land under human settlements has doubled, while the land brought under crops other than tea, rubber, coconuts and paddy has increased by 250 percent.

On the other hand, total land under forests and wildlife and nature reserves has declined by 40 percent, while that taken up by tea plantations and rubber has fallen by 35 to 25 percent, respectively.

Changes in land-use patterns in the hill country of Sri Lanka, defined as areas 300 metres above mean sea level, also present an interesting picture.

The hill country covers around 9,000 square kilometres or 14 percent of the total land area of Sri Lanka.

The most important watershed and catchment area in economic terms is the upper Mahaweli catchment which also happens to be the best documented in terms of land-use data.

Around 54 percent of the total hydropower capacity (or 49 percent of the total power generation capacity) in Sri Lanka, and 23 percent of lands irrigated under major irrigation schemes on the island, are dependant on the water resources of the upper Mahaweli catchment, under a major diversion scheme on the Mahaweli River.

The types of land use which have shown a decrease in the upper Mahaweli catchment include tea plantations (12.7 percent) and rubber plantations (0.98 percent).

On-site

With respect to on-site effects of land erosion in Sri Lanka, it has been found that alternative uses of land in a given agro-ecological environment, under different technologies and cultural management practices, result in significantly different rates of on-site loss of soil resulting from erosion.

The impact of differences in the management of perennial as well as annual crops on erosion rates, as indicated by the erosion hazard ratings (EHR) on a scale of 0 to 40 for upper Mahaweli catchment area shows that, tea with less than 40 percent cover has an EHR of 32 while tea with over 80 percent cover has an EHR of 2.

The removal of fertile top soils as a result of erosion is one cause of land degradation. The other causes are depletion of soil nutrients, damage to physical and chemical properties of the soil, and the reduction in soil capacity to retain moisture.

The loss of nutrients and the reduction in moisture retention capacity are associated with the loss of productive potential of soils.

However, very little quantitative information is available in Sri Lanka on those areas.

Furthermore, a drop in crop productivity and crop yields because of soil erosion and land degradation is an integrated response to several interacting factors such as soil fertility, prevalent climate, incidence of disease and pests, cultural practices, degree of past erosion and associated land degradation, and the current rate of erosion and land degradation.

Recent work carried out on land degradation and productivity in the case of rubber, and some work on tea, suggests that the reduction in yields of perennial crops as a result of land degradation is relatively smaller than in the case of annual crops.

However, the replanting of perennials on degraded land is difficult and the related costs could be a prohibitive factor.

Off-site

The loss of multipurpose reservoir capacity as a result of sedimentation is a major off-site effect. That loss has a major adverse impact on power generation and irrigation of agricultural land in the dry zone.

Significant losses have been reported for some of the large reservoirs such as Polgolla, with an average annual loss of capacity of 2.52 percent for Polgolla and 6.95 percent for Rantambe.

The comparatively faster capacity loss at the Rantambe reservoir may stem from the high percentage of annual crop cultivation in the area.

The other adverse effect is the rainfall run-off ratio. Changes without adequate conservation measures in land use from perennial crops, such as tea, in favour of annual crops may result in reduced reservoir capacity together with increased water yields from a rise in the rainfall run-off ratio.

The net effect of such land-use changes on irrigation and hydropower generation will depend on the relative strengths of their negative and positive effects on reservoir capacity and water yield.

The increased cultivation of annual crops in contrast to perennials in hilly regions also causes damage to roads through increased erosion and rainfall run-off ratios.

High erosion chokes up road drainage systems with silt, and road surfaces become flooded during high-intensity rainfall. Other adverse effects from the changeover to annual crops include frequent failures of road embankments and landslides.

According to the records of the Road Development Authority, the total cost of maintaining one kilometre of A and B class roads in Nuwara-Eliya District of the hill country has increased almost 350 percent during the past five-year period.

Between sectors

There are marked differences between the adverse environmental impacts of the three crops, tea rubber and coconut, when it comes to soil erosion, land degradation and loss of productivity.

The most marked adverse impact appears to occur in the case of replanting high-grown tea on steep slopes.

However, in the case of rubber, although grown on sloping land with fairly high gradients, the problem is not perceived to be so pronounced as rubber trees bind the soil better.

Furthermore, rubber tree replanting is carried out at longer intervals of time.

In order to minimize the effects of soil erosion a deliberate choice of a crop can be made for providing vegetation that has rapid growth characteristics, thereby providing constant ground cover. On rubber plantations, creeping legumes serve that purpose effectively. In the case of tea, a well managed vegetatively propagated tea also provides an excellent cover crop.

However, difficulties arise during the early period of establishing such ground-cover crops. Furthermore, since the chosen cover crop should also yield an economic return, rubber offers an economic advantage over tea.

Coconuts lie at the other end of the scale. With coconut plantations, adverse environmental impacts resulting from soil erosion and land degradation hardly ever arise because the palms are generally grown on flat terrain in the low country.

When it comes to adverse impacts related to excessive use of agrochemicals ( herbicides, pesticides and fungicides), tea has a distinct disadvantage over the other two crops, as it is a directly consumable product.

Hence, more stringent control measures are required to prevent agrochemical residues above the permitted limits being deposited on tea.

However, this question does not arise in the case of rubber, because the end products are for industrial use. As far as hazards related to processed products are concerned, coconuts fall within an entirely different dimension. Very strict control must be maintained over coconut processing operations to prevent the contamination of desiccated coconut with Salmonella.

Organic tea

An issue that specifically affects the tea sector is the growing health concerns among international consumers of food products and the requirement for high standards of quality and organic foods.

In the case of tea, that demand is not so pronounced at present. Although demand for organic tea (i.e., tea produced under strict organic conditions without the use of chemical fertilizers, insecticides, pesticides and fumigants) is limited, it fetches premium prices on international markets.

At present, Sri Lanka exports organic tea in limited quantities. The constraint encountered in the production of organic tea is that bio-fertilizers provide lower amounts of nitrogen (less than 1 percent) than chemical fertilizers.

That is a disadvantage, because tea responds well to nitrogen. As a result, the already low level of productivity is affected further and production costs are increased.

Although organic cultivation is more suitable for systems where intercropping is possible, a positive factor in the use of bio-fertilizers with tea is that it does not lower soil pH which is considered to be a precursory condition for soil erosion.

Another interesting feature of the tea sector in Sri Lanka is the use of environmentally friendly natural materials for consumer packaging of tea.

There is a market preference for such consumer packs in specialized niche markets, as the packaging finds other uses in addition to being biodegradable.

As a perennial crop, well-managed VP tea is a good cover crop, which either minimizes or prevents soil erosion. Estimates of soil erosion under different land uses in the upper Mahaweli catchment areas indicate that annual soil loss per hectare is 15 tons for VP tea compared with 20 tons for well-managed seedling tea and 75 tons for poorly managed seedling tea.

It is clear that the estimate for VP tea compares well with other sectors, including the comparable figure for dense forest cover.

Studies on EHR in the upper Mahaweli catchment area shows that over 80 percent cover provides the most favourable rating for VP tea.

Tea replanting in hilly areas by uprooting existing cover is not approved for this reason. Instead, the technique of infilling vacancies is encouraged, to prevent disturbance of the existing overall cover.

Furthermore, in terms of land-use policy in Sri Lanka, only tree crops are permitted on land areas exceeding 60 percent slopes (including VP tea with tree cover) for the same reason.

Management practices

In any event, during cultivation of plantation crops, it is possible to employ a range of environmentally friendly management practices which mitigate the adverse impacts on the environment which result from soil erosion and land degradation;

Forests and green areas constitute two important sinks for ‘greenhouse’ gases (GHG).

In that context, tea, rubber, oil palm plantations play a significant role in the mitigation of GHG emissions.

In addition, the forestry component is an integral part of plantation cropping in Sri Lanka, as it aids in the mitigation process and contributes to biodiversity.

The forestry component of Sri Lanka, especially the tea sector, mainly comprises fuelwood which is used in the industry itself.

As an environmentally friendly renewable resource, forests therefore contribute to the sustainable development of the plantation sector;

The use by the plantation sector of chemicals which cause adverse impacts on the environment is very limited. For example, the quantity of methyl bromide (which is an ozone depleting substance) used as a fumigant by the tea sector is very limited.

In any event, less harmful substitutes are generally available for use with tea.

Another noteworthy feature of plantation crops is that those can be cultivated under organic conditions, particularly with the aid of bio-fertilizers and other environmentally friendly organic practices. However, crop productivity under organic conditions is lower.

Nevertheless, organic produce fetches premium prices in world markets because the demand for such ‘green’ products among health conscious consumers is increasing on international markets.

Sri Lanka has already begun to respond to the demand for organic or bio-teas, albeit in limited quantities at present;

In tea manufacturing, the sector primarily employs maceration and drying processes for green tea leaves which are, by and large, environmentally friendly as they produce very little toxic effluent that impacts adversely on natural resources.

The only exceptions are secondary processed products, such as ‘instant tea’ products which may produce a certain amount of effluent.

Even in such instances, mitigatory measures can be easily introduced. In the case of atmospheric emissions, there is hardly any contribution to the environmental hazard of acid rain as the tea processing industry in Sri Lanka uses either fuelwood or fuel with a low sulphur content.

Climatic change

In the plantation sector, there could be both direct and indirect impacts. Direct impacts will result from increased carbon dioxide levels, which affect photosynthesis, and rising temperature which, in turn, cause heat stress and increased evapo-transpiration in crops.

Indirect impacts will result from changes in moisture levels, an increased incidence of pests and growing spoilage of agro-products as a result of enhanced microbial activity. These effects could result in reduced yields and shifts in productivity.

According to current climate change predictions for Sri Lanka, the effects of climate change by 2050 will be marginal, reaching only +0.50C for temperature increase and +5 percent for evaporation/rainfall (wet season only) in the high scenario.

However, in the scenario for 2010 the changes become quite significant.

The trends also suggest that within the averages, the intensity of dry weather and rainfall may increase. Therefore, climate change could have increasingly significant effects even in the scenario for the year 2070.

Studies on weather patterns and crop yields for the past years have shown that drought affects tea by reducing the yields.

On the other, irregular patterns of rainfall and high seasonal concentrations in the wet zone, with attendant increases in run-off ratios, could result in soil erosion, land degradation and the loss of productivity of plantation crops.