Assessing and reducing the environmental impact of tea cultivation

Full text

Global tea science
Current status and future needs
Edited by Dr V. S. Sharma, formerly UPASI Tea Research
Institute, India
Dr M. T. Kumudini Gunasekare, formerly Tea Research
Institute, Sri Lanka
BURLEIGH DODDS SERIES IN AGRICULTURAL SCIENCE
E-CHAPTER FROM THIS BOOK

http://dx.doi.org/10.19103/AS.2017.0036.20
© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
Assessing and reducing the environmental
impact of tea cultivation
Thushari Lakmini Wijeratne, Tea Research Institute, Sri Lanka
1 Introduction
2 The environmental impact of tea cultivation
3 Making tea cultivation more sustainable
4 Case studies: carbon sequestration and production
5 Summary and future trends
6 Where to look for further information
7 References
1 Introduction
Environmental issues like climate change affect the sustainability of agricultural crop
production all over the world and the plantation sector is no exception. Currently,
there is a growing demand for environmental awareness and precautionary measures
to mitigate or reduce the rate of environmental degradation, or stop it altogether.
Therefore, it is becoming vital to assess the environmental impact of different agricultural
cropping systems. In particular, following the United Nations Conference on Sustainable
Development (Rio+20) in 2012, the global community was urged to follow a sustainable
consumption and production (SCP) strategy. Considering its importance, it was named as
the 12th of the sustainable development goals (SDGs) (UNEP, 2015).
Tea being the most popular, widely consumed beverage in the world has become
an important plantation crop in many countries. As a perennial crop occupying a large
proportion of arable land, assessing its environmental impact would benefit the economy
of tea growing countries immensely.
The environmental impact of tea can be measured by performing a life cycle analysis
(Brentrup et al., 2004). The carbon footprint calculation is one step in the life cycle analysis
in tea production systems. The total CO2 (or its equivalent) emissions from the ‘flush shoot’
to teacup is quantified with the objective of assessing the environmental impact over the
entire production cycle. This should include all the inputs involved in the production of tea
shoots including emissions at different stages of cultivation, manufacturing, packaging,
transportation and consumption. Therefore, the environmental impact has to be considered
at different stages of the life cycle. While considering the environmental impact of tea,
besides greenhouse gas (GHG) emissions there are several other issues to be considered
Chapter taken from: Sharma, V. S. and Gunasekare, M. T. K. (ed.), Global tea science: Current status and future needs, Burleigh Dodds
Science Publishing, Cambridge, UK, 2018, (ISBN: ISBN: 978 1 78676 160 6; www.bdspublishing.com)

Assessing and reducing the environmental impact of tea cultivation
2
© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
as well. Most important amongst them are depletion of abiotic resources, land use, global
warming, stratospheric ozone depletion, human toxicity, ecotoxicity, eutrophication and
acidification (Brentrup et al., 2004). This chapter attempts to address the impact on the
environment at different stages of the life cycle of tea, namely nursery, land preparation,
crop establishment, immature tea, mature tea, manufacturing, transportation (including
both the inputs as well as the product), consumption and also waste disposal. Further,
possible ways and means of reducing such impacts are also discussed with the objective
of reducing the carbon footprint in tea.
2 The environmental impact of tea cultivation
Tea plantations are raised by planting cuttings, seeds or both. The plants are raised in
a nursery for a period of about one year. In order to start a tea nursery, soil fumigation
is carried out with chemicals to eradicate soil-borne pests and diseases, mainly the
parasitic nematodes. Methyl bromide was until recently used to fumigate nursery soil.
However, due to its ozone depleting nature and phyto-toxicity (producing bromide
residues, a groundwater pollutant), its use was banned following the Montreal Protocol
in 1997. As a result, the search for alternate methods of soil fumigation began (Vitarana
et al., 2002).
Tea plantations are established at the expense of natural forests, resulting in the
destruction of biodiversity and soil (Van der Wal, 2008). The destruction of plant species
leads in turn to the loss of many other species too. Consequently, it has been reported
that the number of both the lion-tailed macaque in India and the Horton Plains slender
loris in Sri Lanka, both of which are on the IUCN’s Red List of endangered species,
declined (Smith, 2010; William, 2011). When establishing a tea crop, all the other
vegetation is uprooted and the soil is rehabilitated to prevent soil-borne pest and
disease infestations. During this uprooting of vegetation, the soil is loosened resulting
in significant soil erosion. Also during the crop establishment period, that is, the first
two to three years, there is a high possibility the land will be exposed and become
eroded (Van der Wal, 2008). It has been reported that the tea lands in many places had
lost topsoil in the order of 300–450 mm during the past 100 years which is equivalent
to 3–4.5 million kg ha−1 of soil loss (Zoysa et al., 2008). Yan et al. (2003) reported
that the direct impact of soil erosion on the environment can be on-site as well as
off-site. On-site impacts are a thinning soil layer, deterioration of soil structure and
decreased soil nutrients whereas, the off-site impacts are the pollution of water bodies.
These eroded topsoils accumulate in water bodies reducing their capacities due to
sedimentation. Ultimately, it will lead to flooding and its consequential environmental
hazards. The eroded fertile topsoil also causes algal bloom and eutrophication of
water bodies which disturb the aquatic biota. Further, it will be necessary to apply
more and more fertilizers ultimately increasing energy consumption and changes in
adaptability of land use (Yan et al., 2003). According to Shcherbak et al. (2014) the
emission response to increasing nitrogen fertilizer input is exponential. Therefore,
global warming will also be accelerated causing more harm to the environment than
expected.
Unlike most other perennials, tea is harvested at seven- to ten-day intervals throughout
its lifespan. Therefore, it is necessary to replenish the depleting nutrients continuously

© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
Assessing and reducing the environmental impact of tea cultivation 3
to avoid any economic loss. These intensive cultivation practices necessitate the use of
synthetic fertilizers and chemicals. The monoculture nature of tea plantations aggravates
this issue as they are usually lacking natural enemies and heavily dependent on chemicals
to protect the tea bushes and to achieve higher productivity (Van der Wal, 2008). The use
of such chemicals may cause other environmental hazards such as global warming, soil
erosion and eutrophication. However, studies conducted on those lines are rare. Instead,
many studies have been conducted on the positive impacts of tea cultivation such as
carbon sequestration in different countries and regions (Kamau et al., 2008; Wijeratne
et al., 2014, 2015).
In the tea manufacturing process, old machines are commonly used which consume a lot
of energy. The use of such machines increases the carbon footprint of tea immensely. The
conventional dryers used in Darjeeling tea (Doublet and Jungbluth, 2010) are one such
example. It has been reported that withering, drying, grading and packing tea requires
4–18 kWh per kg of processed tea, in comparison to the need for 6.3 kWh per kg of steel.
Also, it has been reported that in some parts of East Africa, where power is expensive and
unreliable, many tea factories use standby diesel generators which have high polluting
potential (Van der Wal, 2008).
If fuel wood is transported from distant places to tea factories, the carbon footprint
will be increased due to the use of fossil fuel for transportation. Furthermore, if the fuel
wood is not dried properly before using them in furnaces, the carbon footprint would
again be increased as the burning becomes inefficient. Similarly, if the processed tea is
transported far away for marketing, the use of fossil fuel increases again causing a greater
environmental impact. In countries where the total production is consumed locally within
the country itself the environmental impact will be lower compared to countries which
export their products due to long-distance freights creating a greater carbon footprint.
However, as explained by Doublet and Jungbluth (2010) the contribution of transportation
activities to the carbon footprint compared to the cultivation and preparation is much less
and will not significantly affect the carbon footprint of tea.
A calculation of the carbon footprint has been developed for tea plantations in India and
Kenya and these were used in tea promotion campaigns. Several companies are currently
practising this strategy, trying to use these values as a marketing tool. But the availability
of research papers on the same in peer-reviewed journals is still scarce. According to
a study done by Nigel Melican as mentioned by Sauer (2009) the carbon footprint of
tea varies from 200 g CO2 per cup to −6 g CO2 per cup depending on how it is grown,
processed, shipped, packed, brewed and discarded. Also, it was mentioned that loose
leaf tea would have an average of 20 g CO2 per cup whereas, that of a teabag would be
ten times higher due to the use of carbon-intensive packaging.
According to Munasinghe et al. (2013), boiling water to prepare tea is one of the highest
energy consuming activities affecting the carbon footprint of tea which is in agreement
with the findings of Azapagic (2013) and Doublet and Jungbluth (2010). In fact, around
70% of the total impact results from the use of electricity for boiling water to prepare tea.
According to the results of Nigel Melican as mentioned by Sauer (2009) when electricity
is used for boiling water, energy is wasted at many different stages such as at the point of
electricity generation, grid losses along the wires, transformer losses as voltage is stepped
up and down and finally through heating water in the kettles. All these wastages account
for the increase in carbon footprints and the consequential environmental impact of tea.
Finally, if the remaining consumed tea is discarded properly it provides a good opportunity
to reduce the carbon footprint through recycling.

Assessing and reducing the environmental impact of tea cultivation
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© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
3 Making tea cultivation more sustainable
As a result of an increased desire to minimize environmental impacts, many environmentally
friendly alternatives are being tested for methyl bromide including soil solarization, the use
of metham sodium, dazomet and different organic formulations in different concentrations.
Sri Lanka has been recorded as the first tea growing country which has totally phased out the
use of methyl bromide and thereby earned the ozone-friendly label (Gunawardena, 2011).
Soil rehabilitation is a common practice before replanting tea in all tea growing
countries. This is done to recondition the soil. Due to the monoculture and perennial
nature of the crop, the tea lands are depleted of nutrients and there is a high possibility of
building up soil-borne pests and disease causing organisms. Use of mana (Cymbopogon
confertiflorum) prior to replanting is a good way of controlling nematode infestation
without using chemicals. It also increases the organic content of the soil. The addition of
compost, cover crops or mulching will also help to increase the organic matter in the soil
immensely.
High doses of synthetic fertilizers are conventionally applied to obtain better yields and
tea growth. However, it has been reported that the same results could be obtained using
low levels of nitrogen (N) and phosphorus (P) together with microbial inoculants compared
to the use of a chemical fertilizer alone or the inoculant alone (Nepolean et al., 2012; Saikia
et al., 2011). According to recent studies on biofilm biofertilizers (BFBF), it is possible to
reduce the use of recommended chemical fertilizer by 50% at the nursery stage when it
is applied with BFBF (De Silva et al., 2014). Also, it has been found that the use of site-
specific phosphorus-solubilizing bacteria allows the grower to reduce the use of fertilizer
by one-third which will ultimately reduce the use of synthetic fertilizers (Thennakoon
et al., 2016). Site-specific fertilizer recommendations prevent the use of chemical
fertilizers unnecessarily without compromising the crop yield. It replenishes the soils with
only the depleted nutrients, thereby reducing fertilizer wastage which would ultimately
reduce eutrophication and algal bloom. Similarly, slow-release fertilizers release nutrients
according to the requirements of the plants, thus reducing environmental pollution.
Improving the organic content of the soil will also improve the fertilizer use efficiency
while reducing wastage. Organic cultivation also increases the soil carbon pool, thereby
reducing the atmospheric CO2 concentration and mitigating climate change (Cracknell
and Njoroge, 2014). Furthermore, the addition of organic inputs increases the efficient use
of fertilizers and reduces indirect emissions associated with fertilizer production. Also, it
leads to reduced soil erosion, another GHG emission source, by binding the soil particles
together.
Well-managed tea produces good canopy cover which ultimately protects the land by
reducing splash erosion. However, during the crop establishment period it is necessary to
apply thatching materials to cover the soil which will reduce the evaporation of water and
splash erosion. Development of contour drains with lock and spills and leader drains will
drain excess water efficiently from the tea lands without eroding the soil.
Where tea is cultivated with shade trees, a lot of environmentally positive impacts can
be achieved while achieving economic benefits through improved yields. They help to
improve the micro-climate surrounding the tea bushes which will ultimately improve the
physiology of tea and help to utilize the inputs efficiently resulting in lower wastage. They
prevent direct contact of rainwater on the ground and reduce the speed of rainwater
resulting in less soil erosion. The addition of shade tree lopping into the tea plantations
will increase the organic carbon content (OC) of the soil which will ultimately reduce

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Assessing and reducing the environmental impact of tea cultivation 5
the quantity of applied fertilizer as well as its wastage. It will also help to improve the
microbial activity in the soil. Shade trees provide nesting and resting places for birds and
other fauna which will act as natural enemies for the pest and disease causing organisms.
Furthermore, it has been observed that tea plantations which comprise tea and shade
trees have comparable carbon sequestration potentials to the reported values of agro-
forestry systems (Wijeratne, 2015; Wijeratne et al., 2014a,b,c). This carbon sequestration
potential of tea plantations will be useful in reducing the carbon footprint of tea. Also,
the addition of different types of shade trees and wind breaks will enhance biodiversity
in the tea plantations and together with their lopping will provide a better source of
renewable energy. It is necessary to utilize the lands which are unsuitable for growing tea
to grow fast-growing tree species which can act more as CO2 scrubbers as well as generate
renewable sources of fuel wood for the tea manufacturing process. This will reduce energy
wastage through transportation too. Tea plantations which are accredited by the Rain
Forest Alliance have less environmental impact compared to non-accredited ones as they
avoid the use of synthetic inputs for at least a 5-m distance along the roadsides.
If hydropower is used to generate electricity, the environmental impact could be
reduced compared to electricity generated using coal or fossil oils. Electricity wastage in
the tea manufacturing process can be addressed by using on-site electricity generation
techniques such as mini hydropower stations. In that way the energy wastage from electricity
generation to consumption as described earlier could be reduced enormously. However,
the electricity wastage reduction and its environmental impacts using mini hydropower
needs to be balanced against the resultant environmental impact on the spray zone and
downstream vegetation. It has been reported that the unique forest vegetation present in
the spray zone of waterfalls are badly affected and face the threat of extinction due to the
construction of mini hydropower stations (Silva and Silva, 2016).
New energy efficient technologies should be adopted rather than using the old and
inefficient methods of tea manufacture. The use of energy-saving stoves, energy-efficient
boilers and the replacement of factory lights with LED bulbs are some examples. Fluidized
bed drying where hot water is blown directly into the dryer and the process of fluidization
moves the tea leaves can be adopted instead of conventional tea drying as it saves a lot
of energy, in fact almost half the amount (Doublet and Jungbluth, 2010). Obtaining fuel
wood for factory production from sustainably managed forests that do not reduce the area
or density of natural forest cover and drying them well to about 20% moisture content
ensures optimum calorific value (Cracknell and Njoroge, 2014).
Also, production of tea in bulk should be promoted as far as possible as it has a much
lower environmental impact compared to teabags. When it is necessary to make teabags,
recyclable materials should be used. Bulk tea can also be packed using reusable containers
or recyclable paper.
As the highest energy use in the life cycle of tea is at the consumption stage, alternate
tea which uses cold water instead of boiling water will help to reduce the carbon footprint
immensely. The production of cold-water-soluble instant black tea (Perera et al., 2016) is
a good alternative. Also reducing the amount of boiling water and using energy efficient
kettles are the other options to reduce the carbon footprint of tea. Further, using gas
instead of electricity to boil the water would help to reduce the carbon footprint of tea as
then there will only be one step of energy loss that is, from burning fossil fuel to increasing
the water temperature (Sauer, 2009). The carbon footprint of tea can be further reduced
by heating water in a closed vessel as then the evaporative loss of water is prevented
(Munasinghe et al., 2013).

Assessing and reducing the environmental impact of tea cultivation
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© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
At the time of disposal of used tea, it would be better if it was composted rather than just
thrown away. Also, waste tea can be used to remove bad odours from the household or
in beauty cultural activities. The cardboard and plastic wrappings should be recycled and/
or reused without being dumped in landfills. In addition, the tea factory wastes should be
disposed of properly by separating the solids from wastewater and composting, reducing
the pathogens from the wastewater and the dissolved chemical/nutrients to acceptable
levels, and aerating the wastewater to reduce CH4 emission. Constructed wetlands and
gravel bed hydroponics can be used to treat the wastewater (Cracknell and Njoroge,
2014).
4 Case studies: carbon sequestration
and production
As it has been identified that the CO2 emissions at the cultivation stage are one of the major
contributors to the increase in the carbon footprint of tea, the following two case studies
were conducted to discover the potential of carbon sequestration and CO2 emissions in
major tea growing regions of Sri Lanka.
4.1 Measurement of carbon sequestration potential
of tea plantations in Sri Lanka
Carbon sequestration is a concept which has gained attention as a feasible and cost-
effective option in mitigating climate change. The principal objective of the present work
was to estimate the carbon sequestration potential of Sri Lankan tea plantations using
experimental fieldwork. There, the actual carbon sequestration of tea in different tea
growing regions of Sri Lanka, namely Low-country (LC), Mid-country (MC), Up-country
(UC) and Uva, was estimated using the stock difference method of the Inter-governmental
Panel of Climate Change. Standing biomass and carbon concentrations of different
parts of seedling and VP (TRI2025) tea plants were measured by destructive sampling in
selected tea plantations with similar management using the oven dry method and Walkley
and Black method, respectively. Sampling on two occasions with a considerable interval
between the two sampling enabled estimation of carbon sequestration rates based on the
rate of average net carbon storage in biomass. Biomass and carbon gain of selected high
and medium shade tree species were also estimated using allometric equations.
Estimations from the experimental fieldwork showed that seedling tea plants are superior
to VP tea plants in sequestering carbon. The differences in percentage distribution of total
biomass within the tea bush in seedling and VP tea were identified as the major reasons
for this observation.
The addition of shade trees in tea plantations increased its carbon sequestration potential
substantially. Tea plantations with high and medium shade trees in LC, MC, UC and Uva
had carbon sequestration potentials of 6.7, 3.5, 2.3 and 5.1 Mg of C ha−1 yr−1, respectively
(Fig. 1). These values were comparable with the reported carbon sequestration values of
smallholder agro-forestry systems and mesic savannas but lower than those for tropical
rainforests. This study further emphasized the need to establish and manage shade trees
in tea plantations not only to enhance yields, but also to ensure better environmental
resilience. Therefore, based on management, extent of cultivation and perennial nature,

© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
Assessing and reducing the environmental impact of tea cultivation 7
the carbon sequestration potential of tea plantations in Sri Lanka is significant in mitigating
climate change. Also, possibilities should be explored for securing payments for carbon
sequestration by tea plantations to compensate for economic losses due to possible yield
reductions as a result of climate change, especially in warmer regions.
4.2 Determination of soil respiration in UC and LC
tea growing regions of Sri Lanka
Soil respiration (SR) is defined as total CO2 production in soils resulting from the respiration
of soil organisms and roots. SR is an important function in terrestrial ecosystems as it
contributes to global carbon cycling and climate change. Determining SR values or
the CO2 efflux is important in this context. The total global emission of CO2 from soil is
recognized as one of the largest fluxes in the global carbon cycle and small changes in
the magnitude of SR could have a significant effect on the concentration of CO2 in the
atmosphere. As tea (Camellia sinensis (L) O. Kuntz) is one of the most important plantation
crops grown in a large proportion of Sri Lanka, it is of the utmost importance to get an
idea about CO2 emissions from tea lands to remain as a profitable industry. Therefore,
this study was carried out to discover the CO2 emissions in UC and LC tea lands, the two
extremes of the tea growing regions in Sri Lanka during both wet and dry seasons. The soil
samples were collected along the active root zone depth of the tea plants, that is, up to a
depth of 0–45 cm from experimental sites using a stratified random sampling technique
taking the tea growing region as the main strata. Soil moisture content was measured
gravimetrically and OC was measured using the Walkley–Black method in parallel with
0
1000
2000
3000
4000
5000
6000
7000
LC MC UC UVA
Carbon sequestration potential
(kg of C ha–1yr–1)
Tea Growing Region
100%tea+100%HS+100%MS
100%tea+50%HS+50%MS
100%tea+0%HS+0%MS
Figure 1 Carbon sequestration potential of tea plantations of Sri Lanka with different densities of high
shade (HS) and medium shade (MS) trees in different tea growing regions of Sri Lanka (Low-country
(LC), Mid-country (MC), Up-country (UC) and Uva).

Assessing and reducing the environmental impact of tea cultivation
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© Burleigh Dodds Science Publishing Limited, 2018. All rights reserved.
SR measurements using the Anderson method. Twelve replicates were taken for each
treatment. The relationships of SR with the soil moisture content and OC were developed
using regression analysis. Data was analysed using SAS software package version 9.1 and
the results are given in Fig. 2.
Accordingly, SR was 4.07 mg C m−2 h−1 and 2.16 mg C m−2 h−1 in UC and LC tea lands,
respectively. SR was significantly higher in wet conditions than dry conditions too. The
relationship between SR and soil moisture was highly significant and positive compared to
the OC which was complex and negligible.
5 Summary and future trends
Table 1 presents a brief summary of the major environmental impacts of tea that have
been discussed earlier in this chapter and possible mitigation measures at different stages
of tea production for easy reference.
Environment is a priority area today where climate change occurs as a result of global
warming. Most of the time anthropogenic activities are the main cause of global warming.
The natural environment is altered for the well-being of humans and the consequences are
suffered by all living beings. As a result, the value of the environment has been recognized
by the global community and seventeen SDGs have been identified (United Nations
Department of Public Information, 2016).
Due to growing awareness of the impact of global climate change, it is necessary to
consider the environmental impact of each and every product being traded. This becomes
mandatory, especially with the responsible or SCP concept which is the 12th SDG (United
Nations Department of Public Information, 2016). Munasinghe et al. (2013) explained
that businesses are carefully inspected for the environmental impact of their products
and there is a growing trend for customers to purchase more environmentally friendly
products. Therefore, unless these trends are addressed by the tea industry there will be
no sustainable future for it.
Insufficient research has been conducted into reforming policies which address the
global environmental impact of tea. It is high time to commence such research and
Figure 2 Variation of soil respiration in Up-country (UC) and Low-country (LC) tea growing regions
(means with the same letter are not significantly different at α = 0.05).

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Assessing and reducing the environmental impact of tea cultivation 9
reduce its environmental impact while unveiling the potential to benefit those who follow
environmentally sustainable tea production.
6 Where to look for further information
As this is a comparatively new trend in the world, the availability of peer-reviewed
articles with high scientific reputation is rare. However, most of the basic details can be
found on the internet. Brentrup et al. (2004) clearly explained the theoretical concept of
environmental impact assessment methodology for agricultural systems. Therefore, it has
become possible to conduct new research to assess the environmental impact of different
products on the market and make informed decisions in purchasing the correct product.
Also, the websites of the Inter-governmental Panel on Climate Change, United Nations
Framework Convention on Climate Change, United Nations Environment Programme,
Rainforest Alliance and the Ethical Tea Partnership will provide a fair amount of detail.
7 References
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Brentrup, F., Kusters, J., Kuhlmann, H. and Lammel, J. (2004). Environmental impact assessment
of agricultural production systems using the life cycle assessment methodology I. Theoritical
Table 1 Summary of environmental impacts of tea and possible mitigation measures at different
stages of tea industry
Stage Environmental impact Possible mitigation measures
Cultivation O3 layer depletion Use of alternative methods for soil fumigation
GHG emission Rational use of fertilizers in combination with
organic, BFBF, inoculants and SSFR
Destruction of biodiversity Addition of shade trees, wind breaks and green
manure crops
Soil erosion Development of well-planned drains system,
increase of organic matter content, cover crops, live
mulches etc.
Manufacturing GHG emission Use of energy-efficient machinery
Combustion of fuel wood Use of sustainably managed well-dried fuel wood,
energy-efficient machinery etc.
Environmental pollution
due to wastewater
Separating and treating wastewater before
releasing into the environment, constructed
wetlands and gravel bed hydroponics
Consumption GHG emission Use of energy-efficient kettles, boiling only the
required amount of water, use of cold water soluble
tea

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