Problems related to pesticide spraying on paddy
rice and solutions
T.Gut1, M. Lamers1, V.V.
Nguyen2, T. Streck1
1
1Institute
of Soil Science and Land Evaluation. Biogeophysics, University of Hohenheim
2Institute
of Plant Pathology, Hanoi University of Agriculture
corresponding author: T. Gut, [email protected]
- subproject B5.2
Structure
• Part 1: problems and
recommendations for surface
waters (fish ponds and rivers)
• Part 2: Problems and
recommendations for
groundwater wells
• Part 3: General issues,
recommendations and
instructions
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Introduction
What are the problems related to pesticides in general?
• Pesticides are very toxic not only to pests on rice fields, but also to
almost all other organisms in the environment, including humans.
• Therefore, it is neccessary to prevent pesticides from being
transported away from paddies and from occuring in water and food.
• Thus, not only direct contact, but also indirect uptake and
contamination needs to be prevented.
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – Surface waters
Results – pesticide runoff losses to river
quantification of runoff losses of imidacloprid (a.i. in Conphai and Miretox)
Season
Ban Put outlet
Summer 2008
Ban Ngoang outlet
n.d.
16 % 1
Summer autumn 2010
2.28 %
8.20 %
Spring 2011
1.20 %
2.77 %
Summer autumn 2011
3.83 %
9.19 %
1:
Lamers et al., 2011
• losses of pesticides can be up to 16% of applied amounts
• losses are always higher in summer-autumn crop than in spring
crop due to strong rain events
•  high amounts of the sprayed pesticides don´t stay on the paddy
field, but go to other areas where they should not be
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Results – pesticide losses to fish ponds
• Infiltration of water through bunds is nearly as important as surface
runoff
• Concentration of pesticides in fish ponds were up to 0.5 µg/l for
Fenobucarb (very toxic to fish) and 0.6 for Imidacloprid (very toxic to
small animals in ponds)
• Water pathways through bunds are mainly occuring in macropores,
which come from roots (e.g. Taro) and animals (e.g. crabs)
Bund
surface in and outflow
Soil water fluxes
Irrigation
Drainag
e
Paddy field
Plough pan
Fish
pond
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Results – pesticide losses to fish ponds
• The question is: How does this flow happen exaclty?
• How can it be prevented?
Bund
surface in and outflow
Soil water fluxes
Irrigation
Drainag
e
Paddy field
Plough pan
Fish
pond
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Results – surface waters
Results – pesticide losses to fish ponds
• The question is: How does this flow happen exaclty?
• How can it be prevented?
answer: Flow through bunds happens mostly
through large cracks, root channels and holes
dug by animals (e.g. crabs)
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Recommendations
– surface waters
• Always close the paddy field’s inlet and outlet
while spraying and keep it closed for 1 day or more
• Don´t spray shortly before raining
• Regularly check bunds for holes and repair bunds regularly, if
possible improve bunds with plastic tarp. Take special care of the
bunds when application of pesticides is planned and a few days
after application
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Problems – fish ponds
Testing of fish health and mortality when fish are eating pesticide contaminated grass
has shown strong negative effects of pesticides on fish health
pictures: J. Pucher
 clearly visible damage to grass carp health when fish eat pesticide treated grass
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Problems – fish ponds
Results – pesticide poisoning of crass carp
Testing of fish health and mortality when fish are eating pesticide contaminated grass
has shown strong negative effects of pesticides on fish health
Ofatox
1x f.p.
Ofatox
2x f.p.
no pesticides
Nibas
1x f.p.
Nibas
2 x f.p.
Concentrations of glucose and cholinesterase activity in blood serum of grass carp before the trial
(T0), and after 10 days of feeding grass treated with pesticide products. (f.p. = common farmer
practice)
 measurable damage to grass carp health when fish eat pesticide treated grass
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Recommendations
– fish poisoning
• Besides the previous recommendations to prevent pesticides from
flowing into the fishpond with drainage water and through bunds, it is
also important to avoid pesticide poisining of fish by contaminated
feeding material.
•  Don´t feed grass from bunds or paddies after spraying of
pesticides!
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Problems – Groundwater
wells
Results – groundwater contamination
•
•
Of 17 wells, 7 were permanently polluted with pesticides from rice paddies
Peak concentrations reached 4.0 µg/l, which is 40 times higher the
European threshold value.
pictures: K. Schumacher
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Problems – groundwater wells
Results – groundwater contamination
Group of Depth [cm]
wells
Average
no of
users
Water
used
[l/week]
Well
Mean groundwater table
Whole set
235-1435
20-1285
18.5
700-27000
Polluted
wells
235-645
20-445
12.7
Unpolluted
wells
445-1435
260-1285
23.4
Distance
to rice
paddy [m]
Quality
perception
good
bad
0-118
58.8
41.2
700-9000
1-6.4
28.6
71.4
2700-19000
0-118
80
20
• Polluted wells tended to be less deep, used by less persons and had a lower
rate of consumption
• Wells more than 6.4 m away from paddy fields were always unpolluted
• The groundwater quality perception of well users also reflected the results
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
Recommendations –
Groundwater wells
•
•
Avoid wells in paddies or close to paddy during pesticide spraying season
(a distance of 10 m is good). Try to access water from deep wells far away
from paddies. Also the natural spring behind Chieng Khoi people‘s
committee provides good water quality.
Never wash spraying equipment close to or in wells
pictures: K. Schumacher
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Self-protection
Results from interviews and personal observation show lacking safety awareness. Therefore:
Wear a breathing
mask and protect
your eyes as these are
the most dangerous
entries for potential
unhealthy substance
to enter your body
(renew filter every
10-30 times)
Wash yourself and
your equipment
after each spray
In general:
-Don´t spray
against the wind,
so pesticide is not
blown towards or
“against you”
- handle with care
when preparing
the pesticide
mixture in the tank
Use gloves that
protects hand and
wrists
Wear protective clothes and
shoes that can be washed or
disposed after each usage
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Spraying instructions
• Generally the most pesticides are no threat to your health, if the
recommendation of the manufacturer are followed
• The most pesticides are sprayed in concentrations which are not
dangerous for humans, however the undiluted pesticide formulation
might be toxic and should be handled with care (wear gloves!)
• Low concentrations can still be unhealthy if
inhaled, therefore breathing masks are
highly recommended
• Ensure that pesticide residues do not get
into the water of nearby river, pond or well,
as they are accumulating and dangerous for
humans and also highly toxic for aquatic
organisms
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Spraying instructions
•
•
•
•
•
•
•
Repeated exposure may cause allergic disorders.
Interacts with alcohol - avoid alcohol on days of spraying pesticides.
Avoid contact with eyes and skin.
Wash hands after use.
If poisoning occurs contact a doctor
Don´t spray on flowering plants and/or
Stop spraying at least 15-20 days before
harvesting
• Don´t spray shortly before raining
• Always close the fields inlet and outlet
while spraying and keep it closed for
at least 1 day
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Spraying instructions
Importance of closing the in and outflow of paddy when spraying pesticides
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Spraying instructions
Adjusting the closure period: 0, 5, 10, 15, 20 and 25 hours after pesticides
application
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564
General recommendations
- Spraying instructions
La Nguyen demonstrated
with a computer model that
a closing time of 24 hours
after spraying reduces
pesticide losses by 98 %!
graph by: La Nguyen
Son La, 18.05.2012
Thus, with a few simple improvements, not only the contamination
and poisoning of water, food,
organism and humans can be
reduced effectively, but also the
effectivity of spraying pesticides is
increased, meaning also a reduction
in labor amount and invested money
in paddy rice production.
[email protected]
www.uni-hohenheim.de/sfb564
Thank you!
Xin cảm ơn
Son La, 18.05.2012
[email protected]
www.uni-hohenheim.de/sfb564