34 UTAR AGRICULTURE SCIENCE JOURNAL l VOL. 3. NOVEMBER 2017
Agriculture and Water Pollution Risks
As the pressure to produce more food for the growing population becomes greater, the
agriculture sector can endanger freshwater resources with its organic and inorganic waste.
This article aims to shed some light on the drivers, issues and consequences created by the
By Casey Ng
griculture in Malaysia can be categorized
into two sectors, namely the industrial plantation
sector and the smallholders' sector. Both
sectors rely heavily on regular application of
fertilizers and pesticides to boost productivity,
and substantial amounts of waste are produced.
These are often diffused into the environment
by leaching to groundwater and runoff to
surface water bodies. Such dissemination can
be diffused over a large area (non-point source)
or concentrated by location (point source).
Water pollution is typically associated with (1)
fertilizer run-off, (2) biowaste build-up, and
(3) pesticide accumulation in groundwater and
surface water bodies.
Figure 1. Spraying of chemicals in crop production
Taking rice farming as an example, growing
the crop requires nutrients such as nitrogen,
phosphorus, potassium and other elements
to enhance growth. These have to be applied
continuously to feed the crop.
Generally, two forms of fertilizers are available:
natural organic manure and synthetic fertilizers
produced in factories. Rice farming also
requires the application of toxic chemicals to
keep pests at bay. Applied prudently, fertilizers
and pesticides increase yield and this is crucial
for ensuring food security in Malaysia where
rice is staple. However, applied in excess or
in an uncontrolled manner, they will taint the
surface water. It has already been demonstrated
by various studies that rice cultivation is one
of the key sources of environment pollution
(Ramachandran et al., 2006; Hod, 2011). These
studies also show that farmers themselves are
exposed and gradually poisoned when they
work in pesticide-sprayed elds. Heavy metals
have also been discovered in paddy eld waters
and these have been attributed to excessive use
of agrochemicals which are known to contain
cadmium, copper, lead and zinc (Ismail, 1994).
Also, the application of phosphate fertilizers
may increase metal content in soil and water in
the paddy elds as it is typically produced from
phosphate ore that naturally contain impurities
such as chromium, cadmium, mercury, lead
and iron (Dissanayake and Chandrajith, 2009;
Nagajyoti et al., 2010).
Figure 2. Consumption of pesticides per unit of arable land and permanent crops (g/ha) in selected countries for
Source: Adapted from Mateo-Sagasta and Burke (2012)
AGRICULTURE AND WATER POLLUTION RISKS
Fungicides & Bactericides
Republic of Korea
United States of America
Fungicides & Bactericide
Republic of Kore
United States of
36 UTAR AGRICULTURE SCIENCE JOURNAL l VOL. 3. NOVEMBER 2017
There are sustainability guides or standards that
can be incorporated into rice farming and one
such prominent guide is the Rice Check which
was rst established in Australia in 1980s. In
Malaysia, the Rice Check was introduced by the
Department of Agriculture in 2002 and the main
intent of the guideline was to introduce to farmers
the tenets of responsible agriculture and the
best practices of agrochemical usage. However,
Hairrudin et al. (2012) found that pesticides are
still generally excessively applied in the paddy
elds, particularly toxic Category II and III
products. This was also echoed by Zainalabidin
et al. (2016) when they assessed paddy farmers
in Sungai Petani, Kedah, with questionnaires
derived from the Rice Check. They found 80%
of respondents did not conform to the guideline.
On average, the respondents scored less than 40
on a scale of 0-100. This is alarming as it is quite
obvious the overly applied toxic chemicals are
ending up in the rivers when water is drained out
in the process of paddy planting.
As illustrated in Figure 3, insecticide use has
decreased but herbicide use has increased. The
changes may have been driven by the expansion
of oil palm estates into areas which were
traditionally planted with fruits, vegetables and
other domestic food crops. Food crop farmers are
typically heavy users of insecticides and with the
introduction of oil palm which is not commonly
susceptible to insect pests, insecticide use would
have declined while herbicide use would have
increased for control of weeds in the plantations.
Although DDT-based compounds are banned,
traces have been found in Cameron Highlands
(The Star, 2013; Malay Mail, 2015) where fruits
and vegetables are commonly grown.
Figure 3. Tonnes of active ingredients used by agriculture sector in Malaysia. Although the use of insecticides has
decreased signi cantly since 2011, herbicides usage appears to be on the rise.
Source: Graph is derived from of cial data reported on FAO Questionnaires archived in http://www.fao.org/faostat/
2006 2007 2008 2009 2010 2011 2012 2013 2014
HerbicidesFungicides & Bactericides
As for herbicides, the most common active
ingredient applied is glyphosate and it is sold
as a broad-spectrum, non-selective, weed killer
under various brand names. Glyphosate-based
herbicides (GBHs) were rst developed to as
a defoliant of illegal marijuana plantations in
Mexico and South America to ght the drug
war (Franz et al., 1997). Glyphosate works
by blocking the production of tryptophan,
phenylalanine and tyrosine, and the lack of
these amino acids leads to rapid necrosis
in plants (Amrhein et al., 1980). It is also
highly water soluble thus glyphosate can be
transported in plants from the leaves to the
roots. Such rapid uptake by spraying makes
GBHs the most sought after and heavily applied
pesticide globally. When used carelessly, GBHs
may enter aquatic systems through spillage,
spray drift, leaching and surface run-off. At the
time of this writing, detectable concentrations
of glyphosate have been found in humans,
livestock and underground water (Sanchís
et al., 2011; Mörtl et al., 2014; Krüger et al.,
2014; Dragus and Ristoiu, 2015). This pushes
the entire human population towards health
risks as glyphosate has been linked to various
human ailments (Benachour and Séralini, 2009;
Chaufan et al., 2014; Jayasumana et al., 2014;
Myers et al., 2016)
It is no secret that each farmer has his own
recipe for mixing various brands of toxic
compounds into lethal cocktails for eradicating
pests. The term "pesticide" encompasses all
types of chemicals used to eradicate or control
pests and these include fungicides, herbicides,
insecticides, nematocides and rodenticides.
The use of pesticides is typically higher in food
crops such as fruits and vegetables because
consumers prefer them to appear unblemished
on retailer shelves. Undoubtedly, pesticides
have contributed to crop yield increases
globally. It is also acknowledged that weedicide
use decreases the levels of labour and energy
required for weeding. Unfortunately, chemical
use comes with a cost and Rachel Carson’s
classic book “Silent Spring” published in 1962
was among rst to ignite public concern about
the consequences of pesticide application.
A retired biologist who used to work for the
US Fish and Wildlife Service, Carson detailed
how pesticide DDT “silenced” sh, birds, plants
and the human population in an undisclosed
American town by entering the food chain
and remaining toxic even after it was diluted
by rainwater in the environment. DDT or
dichlorodiphenyltrichloroethane was rst
synthesized by Paul Hermann Müller in 1939
who won the Nobel Prize in 1948 for this work.
It was meant to be applied by soldiers on the skin
during WWII to control lice. After the war, DDT
was marketed as a pesticide. As lawsuits and
criticisms were levelled against Carson by the
chemical companies, many eminent scientists
rose to her defence. Eventually President John
F. Kennedy ordered an advisory committee
to review issues highlighted by the book and
their nal report vindicated Silent Spring. It
was a time when few people were concerned
with environmental degradation but Carson
convinced the public that residual pesticide was
too frightening to ignore. It was reported that
toxic seeped into the soil and washed into the
waterways. Birds were poisoned when consuming
earthworms and humans when consuming shes
(Haberman, 2017). Silent Spring still resonates
loudly today and most countries impose
AGRICULTURE AND WATER POLLUTION RISKS
38 UTAR AGRICULTURE SCIENCE JOURNAL l VOL. 3. NOVEMBER 2017
standards to regulate and control pesticide use.
Nonetheless, in June 1963 when Carson was
given a chance to speak out, she did not call for
the total ban on pesticides. “I think chemicals
do have a place,” she testied (Griswold, 2012).
Indeed, without doubt, agriculture has beneted
from pesticides but are their usage's safety
standards strictly enforced? As more brands
and newly developed lethal pesticides are being
introduced to the market, can the standards keep
up with the ever-increasing range of brands and
As for inorganic ‘chemical’ fertilizers, they may
not be generally toxic but excessive use pollutes
the environment through volatilization, surface
runoff, and leaching to groundwater, rivers,
lakes and seas. Synthetic nitrogen fertilizer
and nitrogen in manure are both subjected to
volatilization when ammonia is formed and
dispersed into the atmosphere. Volatilized
ammonia is eventually deposited into waterways
through atmospheric deposition or precipitation.
The presence of fertilizer compounds in air and
in the water bodies alters the biological system
and consequently the species composition in
In tropical forest rivers and streams where macro
algal growth is minimal, oxygen is dissolved
into pristine water by aeration in waterfalls,
rapids and rifes. DO (dissolved oxygen) levels
in these waters are typically measured at 7-8
When excess agricultural nutrients nd their
way into the local water bodies, they cause
abnormally high phytoplankton and macro algal
growth and alter the oxygen dielcycling (day-
night cycle). They push dissolved oxygen levels
to extremes. Anoxia (0 mg/L), hypoxia (2-3
mg/L), normoxia (5-6 mg/L) and hyperoxia (>9
mg/L) conditions may occur in sequence through
24 hours (Lakani et al., 2013) and get repeated
daily, thus producing “dead zones”.
Oxygen supersaturation, or hyperoxia (O2 >
9 mg/L) is most intense during afternoons due
to strong photosynthesis. In itself this does not
pose any problem because dissolved oxygen
(DO) although excessive, is favourable for
decomposition and breaking down of organic
and inorganic matter and benets aquatic life.
However, DO will start to decrease when sunlight
levels become too low for photosynthesis. At
night, algae and macrophytes consume oxygen
substantially and by early morning hours
DO in water is reduced to anoxia or hypoxia
levels. This causes massive sh mortality and
it is typically termed "early morning mortality".
Besides extreme DO dielcycling, excessive
phytoplankton and macro algal growth also
increases water turbidity and reduce sunlight
penetration. Such unfavourable circumstances
lead to "ecosystem collapse" whereby aquatic
ora and fauna are decimated.
Algae and duckweed can be harvested for organic
fertilizer production through composting.
However, no known attempt has been made in
Malaysia. Most waterbodies do not belong to the
farmers thus legality issues may arise when they
attempt to harvest the algae and duckweed.
Besides eutrophication from uncontrolled use
of fertilizer, there is another major cause of DO
depletion in water bodies - waste from oil palm
mills. The palm oil industry, now Malaysia’s
largest agricultural industry, covers large tracts
of land. Typically 5.0 to 7.5 tonnes of water are
required to produce 1 tonne of crude palm oil
(Ahmad, 2003). The industry's wastewater is
known as Palm Oil Mill Efuent (POME). It is
a brownish viscous sludge with bad odour and
contains 95–96% water, 0.6-0.7% fatty acids
and 4–5% total suspended solids (Parveen et
al., 2010). What alarms the environmentalists
most is POME's high organic and nutrient
content which has roughly 100 times more DO
depleting capability than domestic sewage. In
water physicochemical terms, POME has an
average Chemical Oxygen Demand (COD) of
50,000 mg/L and Biochemical Oxygen Demand
(BOD3) of 25,000 mg/L (Ibrahim, 2012). Thus
POME needs very high levels of DO in the
decomposition treatment process. If this is not
carried out, raw and untreated POME discharged
into the rivers will intensively deplete oxygen
levels in the rivers.
The Environmental Quality Act, 1974, requires
COD and BOD3 to be reduced to 0.0 mg/L and
100 mg/L respectively by treatment processes
before it can be legally discharged into nearby
rivers (Rupani et al., 2010). Naturally, this puts
a hefty nancial pressure onto production cost.
Consequently, it is not surprising that there have
been news reports of mills discharging partially
or untreated POME into nearby rivers and being
ned for non-compliance (Borneo Post, 2016;
Figure 4. Algae bloom in waters is usually a sign of uncontrolled use of fertilizer in the vicinity.
AGRICULTURE AND WATER POLLUTION RISKS
40 UTAR AGRICULTURE SCIENCE JOURNAL l VOL. 3. NOVEMBER 2017
The Star, 2016). In a mail survey of 86 palm oil
mills located in Sarawak and Sabah, Madaki
and Seng (2013) reported that 100% of the
respondents identied that POME is the most
difcult waste to manage in the industry because
it is time consuming and expensive to achieve
COD and BOD3 standard before nal discharge.
It is easy to see why mills are tempted to break the
law because paying nes may be cheaper. POME
pollution in the rivers is not difcult to prove but
there are more than 430 mills around the country
(Madaki & Seng, 2013) which are typically far
away from the ofces of enforcement agencies.
The enforcement agencies are feeble and much
depends on the integrity of mill owners and their
sense of responsibility to the society.
Certainly, there is no shortage of studies and
technologies regarding ways to convert POME
biowaste into fertilizer, dietary substitute for
livestock, provitamin, biofuel, bioplastics or
other products (Prasertsan & Prasertsan, 1996;
Ugoji, 1997; Vairappan & Yen, 2008; Mumtaz
et al., 2010; Rupani et al., 2010). However
few mills are interested. Based on the author’s
numerous conversations with mill managers,
they cite the lack of expertise to process POME
into other products and the difculty of raising
funds to bring in the expertise and technologies.
Thus they prefer to treat POME as waste and not
as by-products. The potential prot margin of
the by-products does not appear to be lucrative
enough to spur the mill managers into action.
Anoxia and hypoxia conditions can also be
caused by untreated manure, biowaste, chemical
residues and wastewater that originated from
poultry, livestock, aquaculture and other
protein-based food production establishments.
In Malaysia, these industries can be classied
under two groups, namely (1) fed, and (2) non-
fed production. In non-fed conditions, livestock
or poultry are free range and left to feed on
naturally occurring food. This is exemplied by
cowherds and shepherds who tend their cattle
and goats to feed in countryside grassland. Some
non-fed aquaculture such as seaweed, oyster and
cockle farming in the coasts are also practiced
as these species can self sustain as long as the
ecosystem where they grow in is healthy.
In fed animal breeding where species are kept
in high density for land optimization, large
amounts of articial feedstock are released into
the farms. Food not completely consumed, and
excreted solids can pollute natural water bodies.
In many cases, feed additives, growth hormones,
antimicrobials, probiotics, antibiotics and other
drugs are also heavily applied and it would not
be surprising if these are already present in local
While diseases typically occur and spread
because of poor hygiene, most aquaculture
farmers, instead of improving sanitation,
take a quick x approach by applying
chemotherapeutants in disease management.
Common disinfectants added into sh ponds
and breeding cages in reservoirs, riversides
and seasides include acriavine, benzalkonium
chloride, lime, teaseed cake, formalin, malachite
green, hypochlorite and poly-vinyl pyrrolidine.
Antimicrobials include chloramphenicol,
nitrofurans, oxolinic acid sulfonamides,
tetracyclines and virginiamycin. (Mohamed
et al., 2000). Being one of the cheapest
Figure 5. Chemotherapeutant compounds are usually
added into water to keep shes free from diseases.
What happens when the water is released into nearby
waterways when the ponds are cleaned?
disinfectants, formalin is widely used in sh
and shrimp hatcheries as a "cure all" remedy
for treating fungi, bacteria and ectoparasite
infestation. In 2012, a total of 18,875 sh
farmers utilized 5,642.31 hectares of freshwater
ponds to produce 163,756.81 tonnes of food
sh. In the same year, 9,658 million freshwater
and brackishwater sh hatchlings/fries were
produced in hatcheries (Yusoff, 2015). One can
only wonder how or whether wastewater tainted
by chemotherapeutants is treated before draining
into the local rivers.
Portable water intake stations are typically
located upriver for the best water quality.
Unfortunately, water-intensive agriculture and
especially aquaculture farms are also commonly
sharing the same vicinities. This raises the
possibility of drinking water sources being
contaminated. Inevitably, whether one is living
in the rural or urban areas, water pollution is
everyone's problem. Nobody is immune because
agriculture-based pollutants drift through from
the highlands to lowlands and nally to seas
where toxic residues can end up in the food and
water we consume. Realizing this, consumers
have started to critically examine their buying
behaviour and are now willing to pay more
to purchase certied organic products grown
without harmful chemicals. The Malaysian
government has also started to encourage
growers to comply to the Malaysian Standard
MS1529:2001 (The Production, Processing,
Labelling and Marketing of Plant Based
Organically Produced Foods).
Best practices such as the use of slow release
fertilizers, organic fertilizers, biological pest
controls and Integrated Pest Management (IPM)
are now mature and advanced. For example,
barn owls (Tyto alba) success in controlling
rodent population in oil palm estates and ducks
(Khaki Campbell and Muscovy) to control apple
snail (Pomacea spp.) in the rice elds is well
documented. All over the world, many countries
have implemented sustainable agricultural
certication standards and good examples can
be taken from Roundtable on Sustainable Palm
Oil (RSPO) for oil palm, Veriora® Sustainably
Grown for ornamental horticulture, Equitable
Food Initiative (EFI) and of course Malaysia's
AGRICULTURE AND WATER POLLUTION RISKS
42 UTAR AGRICULTURE SCIENCE JOURNAL l VOL. 3. NOVEMBER 2017
own Good Agriculture Practice (MyGAP)
which sets the sustainability standards for crop,
aquaculture and livestock sectors.
However, the certication standards are still
voluntary and actual adoption is not going to
be quick and widespread. In the meantime, the
challenge now is in creating awareness among
growers and breeders that food can be produced
with minimal pollution to air, soil and aquatic
systems. Farmers need to understand that
sustainable agriculture isn't just about complying
to standards or meeting consumers' demands
for organic food. The farmers, breeders and
plantation managers need to be concerned about
the health and safety of their own families,
employees and the public.
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