Impact Of Pesticides on Soil and its
MSc EVS Part 1
Roll No 15
• In this study, we see the impact of pesticide use on soil
components and specifically that of enzymes.
• The experiment is designed using the host plant as
• Experiment done in the Gudi village in the
• Experiment shows how the use of various pesticides
result in the decline in enzyme activity in the soil.
• Review summarizes the impact, effect and
management techniques used to reduce pesticide
• Half Life.
• Pesticides is any component of organic or inorganic
origin that is used in order to curb the growth of any
limiting factor affecting the growth of a particular crop
thereby facilitating better growth.
• It covers a wide range of compounds including
insecticides, fungicides, herbicides, rodenticides, mollu
scicides, nematicides, plant growth regulators and
• In this review we will be studying the different impacts
a pesticide has on soil and other components.
Pesticides and India
• India ranks 10th in terms of worldwide pesticide consumption.
• Pesticide Consumption in India was 40672 MT (Technical grade)
during the year 2005.
• There are 186 registered pesticides in India, but of which 85 are
technical grade produced within the country.
• The per hectare consumption in India is 570 g/ha against 2500 g/ha
in USA, 3000 g/ha in Europe and 12000 g/ha in Japan.
• Pesticide consumption in India is the lowest at 0.5 kg per hectare as
against 17 kg per hectare in Taiwan, 12 kg ha-1 in Japan, 6.6 kg ha-1
in Korea, 7 kg ha-1 in USA and 2.5 kg ha-1 in Europe.
• Among all the crops grown in India, pesticide consumption in cotton
is highest (44.5%) followed by paddy (22.8%), sorghum
(8.9%), vegetables (7%), wheat (6.4%), pulses (2.8%) and others
• Among the vegetable crops in India, cabbage is the maximum
pesticide consuming crop.
Classification of Pesticides
• Grouped into 2 main types
1. Hydrophobic, persistent, and bioaccumulable
pesticides that are strongly bound to soil:
organochlorine, DDT, endosulfan, endrin, hep
tachlor,lindane and their TPs.
Most of them are now banned in agriculture
but their residues are still present.
2. Polar pesticides:
Represented mainly by herbicides but they
include also carbamates, fungicides and some
organophosphorus insecticide TPs.
They can be moved from soil by runoff and
leaching, thereby constituting a problem for
the supply of drinking water to the population
Impact of Pesticides
• Though beneficial, they contaminate soil
ecosystem and pose threat to the balance
equilibrium among various groups
microorganisms and components in soil
• Important process like mineralization, nitrification
and phosphorus recycling are dependent much
on the balanced equilibrium existing among
various groups of organisms in the soil.
• They disturb the presence of soil enzymes which
are very key for the above processes and for
• Due to repeated application, insects are
getting resistant to the different cidal agents.
• Also these high concentration of these
pesticides result in their absorption by plants
leading to various ill effects in the entire
Pesticides have various characteristics that
determine how they act once in soil.
• Half life.
Effect on soil fertility
• Soil has millions of tiny organisms including
fungi, bacteria, and a host of others.
• These microorganisms play a key role in
helping plants utilize soil nutrients needed to
grow and thrive.
• Microorganisms also help soil store water and
nutrients, regulate water flow, andfilter
Heavy treatment of soil with pesticides
• Causes populations of beneficial soil
microorganisms to decline.
• Sometimes pesticides have a negative impact
in the available NPK from soil.
• Dehydrogenase does not accumulate extra
cellular in soil and are invariably linked to the
viability of intact cells.
• Hence, its quantification has been recommended
as a useful indicator for testing the side effects of
• Dehydrogenase is considered to play a very
essential role in the process of organic matter
oxidation, particularly in the electron transfer
Phosphatase and Urease
• Soil phosphatases and ureases play a major
role in the mineralization and nitrification
processes of organic substrates.
• Enzymes in soils originate from animal, plant
and microbial sources and the resulting soil
biological activity includes the metabolic
processes of all these organisms.
• Phosphorous is a very important plant
• In the present study, pesticide use and its impact
on selected soil enzymes were investigated with
the following objectives-
To asses the impact of pesticide use on
dehydrogenase, phosphatase and urease activity
To evaluate standard methods of pest and
disease management to reduce impact of
pesticide residues on soil enzyme activity.
• Done basically on 3 points:
1. Persistence of pesticide residues in soil and
its impact on soil enzymes.
2. Effect of organic and inorganic sources of
nutrients on biological activity in soil.
3. Integrated pest management (IPM).
Persistence of pesticide residues in soil
and its impact on soil enzymes
• Approximately 90-95% lindane and 79-89% endosulfan residues persisted beyond 70 days leading
to a decrease in microbial. (Balwinder et.al.)
• Cycon et al. (2005) investigated the effects of insecticide (diazinon), herbicide (linuron) and
fungicide (mancozeb+dimethomorph) on the enzymatic activities in soil The results showed that
the influence of tested pesticides on dehydrogenase, acid and alkaline phosphatase and urease was
• Kabat and panda (2007) reported 92.8 and 60.2 % inhibition of enzymatic hydrolysis of urea by
hydroquinone (concentration- 1 mg/l) and copper sulphate and N thiophosphoric triamide
(concentration – 100 mg/l) respectively.
• Sushma and Singh (2006) observed that residues of these insecticides were monitored during the
entire crop season and their effect on the soil enzymes dehydrogenase, phosphomonoesterase and
arginine deaminase were studied. It was observed that in most of cases insecticides have inhibitory
effect on soil enzymes.
• Shiyin et al. (2004) reported that catalase activities are inhibited when fenvalerate are added to soil
in 15 days, and then the activities began to be stimulated.
Effect of organic and inorganic sources
of nutrients on biological activity
• Dinesh et al. (2000) reported that addition of organic
manures increased microbial activity/diversity and C
turnover, which subsequently led to greater enzyme
synthesis and accumulation in the soil matrix.
• Duffy et al. (1994) reported that biological activity in
soil was greater with organic farming compared to
mixed farming and was the lowest in aerable soils.
• Marcote et al. (2001) found that the organic
amendments stimulated soil enzyme activity but
mineral fertilizers did not.
Materials And Methods
• Experimental details
Design and layout
• The experiment was laid out in Randomized Block
Design (RBD) with four replication and five
• Test crop – Cabbage (Brassica oleracea var.
• Variety – Golden Head N50
• Spacing – 45 cm x 45 cm
• T1 - pest management as per package of
• T2 - integrated pest management.
• T3 - pest management followed by farmers.
• T1 Dimethoate Malathion.
• T2 Dimethoate Neem oil.
• T3 Dimethoate Endosulfan Indoxacarb.
• Soil samples were collected from top 0 – 15
cm layer from each treatment at harvest.
• The collected soil samples were shade dried
for five days, ground in wooden pestle and
mortar, sieved by passing through 2 mm sieve,
mixed thoroughly and partitioned by
quartering technique to get a composite
working soil sample for its analysis and kept in
cold storage till use.
Observation and Results
• Dehydrogenase Activity
All the treatments where an insecticide was applied
were found to reduce the dehydrogenase enzyme
activity significantly in comparison with control.
• Phosphatase activity
In most of the treatments, significant inhibition of
phosphatase activity was recorded reference to the
• Urease Activity
Significant reduction in Urease activity was also seen.
• Pesticides are a very diverse group of
chemicals, hence it is difficult to explore all
• Microbial and faunal populations in time get
tolerant to pesticides though there is
considerable stress on the ecosystem.
• Also major biotic processes such as enzyme
activity, respiration, carbon and nitrogen
mineralization are majorly affected.
Two main methods in order to curb the
harmful effects of pesticides on soil are:
• Organic agriculture
• Integrated pest management
• Organic farming can be defined as “a system
which avoids or largely excludes the use of
synthetic inputs (such as
fertilizers, pesticides, hormones, feed
additives etc.) and to the maximum extent
feasible relay upon crop rotations, crop
residues, animal manures, off farm organic
waste, mineral grade rock additives and
biological system of nutrient mobilization and
• It is a holistic approach that offers equivalent gains in
the interim and substantially improved gains in the
• It is based upon a set of processes resulting in
sustainable eco-system, safe food, good nutrition,
animal welfare and social justice.
• It aims to create ecologically, socially and economically
sustainable system of food and fiber production.
• Finally it is the best way to encourage uncontaminated
food production and at the same time sustain
Integrated Pest Management
• IPM doesn't rely solely on chemicals for pest
• Biological control, cultural practices, and
timely chemical applications are used to
obtain the necessary level of control.
• Pesticides are the last line of defense and are
used only when pest levels are causing
sufficient damage to offset the expense of the
• Scout or monitor crops regularly to check the levels of pest
populations and their damage.
• Implement available non-chemical control practices, including
mechanical, cultural and biological controls, sanitation, and plant
• Use crop rotation , select resistant varieties (plant
resistance), thoroughly clean combines between fields to reduce
weed seed introductions (sanitation) and use cultivation to control
weeds (mechanical control).
• Maximize the benefits of naturally occurring biological controls by
using pesticides only when necessary and selecting pesticides which
are the least harmful to beneficial.
For example, some insecticides and fungicides kill predatory
mites, which can cause a mite outbreaks later in the season
• Only using pesticides that are labeled for the intended crop and pest.
• Considering application site characteristics (soil texture, slope, organic matter).
• Considering the location of wells, ponds and other water bodies.
• Measuring accurately.
• Maintaining application equipment and calibrating accurately.
• Mixing and loading carefully.
• Preventing backsiphoning and spills.
• Considering the impact of weather and irrigation.
• Storing pesticides safely and securely.
• Disposing of wastes safely.
• Leaving buffer zones around sensitive areas.
• Reducing off-target drift.
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