Project Title
Biobeds: The safe disposal and
treatment of pesticide waste and
washings
Project number:
PC/HNS 255
Project leader:
Dr Paul Fogg
ADAS UK Ltd
Gleadthorpe
Medan Vale
Mansfield
Nottinghamshire
NG20 9PF
Report:
Annual report, April 2007
Previous report
N/A
Key staff:
Paul Fogg, Mercedes Franey-Gardiner,
ADAS
Andrew Jukes, Mathew Mitchell, Warwick
HRI
Location of project:
ADAS, Gleadthope
Warwick, HRI
Project coordinator:
Mr Kevin Hobbs, Hilliers Nursery (HNS)
Mr Gary Taylor, Valley Grown Nurseries
(PC)
Date project commenced:
01 April 2006
Date completion due:
30 April 2008
Key words:
Biobeds, pesticide, point source, water,
pollution, waste, treatment
 2007 Horticultural Development Council
Whilst reports issued under the auspices of the HDC are prepared from the best
available information, neither the authors nor the HDC can accept any responsibility
for inaccuracy or liability for loss, damage or injury from the application of any
concept or procedure discussed.
The contents of this publication are strictly private to HDC members. No part of
this publication may be copied or reproduced in any form or by any means without
prior written permission of the Horticultural Development Council.
 2007 Horticultural Development Council
The results and conclusions in this report are based on a series of experiments
conducted over a one-year period.
The conditions under which the experiments
were carried out and the results have been reported in detail and with accuracy.
However, because of the biological nature of the work it must be borne in mind
that different circumstances and conditions could produce different results.
Therefore, care must be taken with interpretation of the results, especially if they
are used as the basis for commercial product recommendations.
 2007 Horticultural Development Council
AUTHENTICATION
We declare that this work was done under our supervision according to the
procedures described herein and that the report represents a true and accurate
record of the results obtained.
Dr Paul Fogg
Principal Research Scientist
ADAS UK Ltd
Signature ............................................................
2007..................
Date .....27 April
Report authorised by:
Mr Simon Groves
Operations Manager
ADAS UK Ltd, Integrated Water and Environmental Management
Signature ............................................................
2007..................
 2007 Horticultural Development Council
Date .....27 April
 2007 Horticultural Development Council
CONTENTS
Page
1
Grower Summary
1
Headline
1
Background and expected deliverables
1
Summary of the project and main conclusions
2
Financial benefits
2
Action points for growers
2
2
4
Science section
Introduction
4
Materials and Methods
4
Results
11
Conclusions
12
Technology transfer
12
References
15
 2007 Horticultural Development Council
Grower Summary
Biobeds: The safe disposal and treatment of pesticide waste and washings
Headline
Initial results indicate that the biobed matrix material (biomix) is able to degrade relatively
high concentrations of a range of pesticides used by both the Protected Crop and Hardy
Nursery crop sectors.
Background and expected deliverables
Routine monitoring of environmental waters has shown that contamination with pesticides
does occur.
In order to meet government targets on reducing the levels of pesticides in
water, improvements to the way in which they are handled and any associated waste
disposal needs to be considered.
Pesticides handling activities are typically performed on the same site due to location of
the pesticide store and a clean water supply.
Research suggests that 20-70% of the
pesticide contamination measured in water can be attributed to spray fill sites.
While the
characteristics of the filling area, operating practices and local conditions may vary the
reasons for the origins of the contamination are generally similar.
Sprayer filling, poor
empty package management and machinery maintenance are the main reasons attributed to
contamination.
Such ‘point source’ releases can be minimised by modifying handling practices in order to
minimise losses.
However, it is inevitable that some releases will occur.
treatment methodologies are therefore required to reduce these releases.
Additional
These treatments
would supplement good handling practices that reduce inputs to aquatic systems.
These
methodologies need to be cheap to use and require low labour and time inputs.
One
possible approach is to use a lined biobed to intercept and treat contaminated runoff from
the farmyard and/or drips and spillages arising during the filling process.
The main expected deliverables from this project are:
 2007 Horticultural Development Council
1

An evaluation of the ability of the biobed matrix material to degrade relatively complex
mixtures of pesticides, typically used by the Protected Crop and / or Hardy Nursery
stock sectors.

An evaluation of the impact that plant growth regulators are likely to have on the
degradation performance of the biobed matrix.

An evaluation of the impact that soil sterilant materials have on:
a) soil microbial activity in the biobed
b) the ability of the biobed to buffer such additions
c) the recovery rate of the microbial population and
d) overall impact on pesticide degradation.

The design and development of a novel biobed system that has limited footprint area
and could potentially be used indoors.
Summary of the project and main conclusions
Experiments have been designed to determine the potential for biobeds to treat a range of
pesticides commonly used by the Protected Crop and Hardy Nursery Stock sectors.
results indicate that the biobed
matrix material
Initial
(biomix) is able to degrade high
concentrations of a range of pesticides. More importantly, the data indicated that risk of
pesticides accumulating in the biobed is low.
Ongoing studies are investigating the impact
of pesticide mixtures and also the impact of plant growth regulators and soil sterilant
materials on biobed performance.
Industry has been consulted on a proposed biobed
design with a footprint area of approximately 4m2.
Construction and controlled testing of
this system is due to commence this spring / summer.
Financial benefits
It not possible to provide an indication of the financial benefit until there is sufficient data
to demonstrate that the ‘horticultural’ biobed works.
Action points for growers
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
With the introduction of the Agricultural Waste Regulations in May 2006, lined biobeds
are now regarded as waste treatment systems and as such require a waste
management licence.

Biobeds built prior to May 2006 have benefited from a 12 month transition period,
which expires in May 2007.
In September 2006, in keeping with its commitment to minimise the administrative burden
on growers and to make the widest use of exemptions, Defra and the Welsh Assembly
consulted upon a proposal for a new waste management licensing exemption for the
disposal of dilute pesticides washings into a lined biobed.
The purpose of the exemption
is designed to improve the management of pesticide washings and to reduce the risk of
pollution from pesticide handling and equipment cleaning activities.
expected in May 2007 this year.

An announcement is
It is anticipated that biobed will be made exempt.
Growers interested in the biobed technology may wish to consider registering an
exemption to enable the installation of a biobed system at some point in the future.
 2007 Horticultural Development Council
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Science Section
Introduction
Biobed technology works on the basis of filtration followed by microbial breakdown of the
retained pesticides (Torstensson and Castillo 1997).
The biobed mixture has to be
capable of degrading complex mixtures of predominantly fungicides, insecticides, plant
growth regulators and possibly detergents, when used in a commercial horticultural setting.
Studies (Fogg et al., 2003a,b) have shown that when pesticides are applied as a
mixture, the degradation rates of certain pesticides can be reduced.
In addition, certain
pesticides have been shown to inhibit the degradation of other pesticides (Motonaga et
al., 1998).
Laboratory-scale incubation experiments were therefore used to demonstrate
the ability of the biobed system to degrade individual pesticides and mixtures of the same
pesticides, and to establish whether the use of plant growth regulators and sterilant
products could permanently effect the degradative ability of the biobed, prior to the
establishment of a demonstration biobed system.
The laboratory studies consisted of five specific experiments:
1
To determine the DT50 of individual pesticides in biomix
2
To determine if a mixture of pesticides affected degradative ability of the biomix
3
To determine if the rate of degradation of the 9 pesticide mixture is impaired
by the use of a soil sterilant applied at maximum recommended rate at the
same time as the pesticide mix
4
To determine the DT50 of a plant growth regulator applied at the maximum
recommended rate in the presence and absence of the 9-pesticide mixture.
5
To determine the impact of a soil sterilant on the soil microbial nitrogen
content, and to assess how well the biomix matrix recovers both in the
presence and absence of additional non-sterilised biomix
Only the results from experiment 1 are reported here.
 2007 Horticultural Development Council
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Materials and Method
Test pesticides
The pesticides used for the laboratory experiments were chosen based on those commonly
used in horticultural nurseries and therefore those likely to be found in washings.
Nurseries provided ADAS with chemical use records, and Pesticide Usage Survey (PUS)
data for 2004 were also studied.
From this research, a suite of chemicals was chosen.
Finally, refinements were made to the choices based on the ability to analyse for the
compounds.
The chemicals chosen are listed in (Table 1).
Table 1: Properties of selected pesticides
Trade Name
Active
Use
Fungicide
%
active
(w/w)
23.1%
DT50
soil
(days)*
7-56
Koc
(mL g-1)*
Solubility
(g L-1)*
Syngenta
Amistar
Azoxystrobin
500
slightly mobile
6
Tripart
Defensor FL
Carbendazim
Fungicide
43.0%
8-32
200-250
moderately mobile
29
AgriGuard
Chlorothalonil
Certis B-Nine
Chlorothalonil
Fungicide
40.4%
5-36
0.00081
Plant
Growth
Regulator
85.0%
02***
1600-14000
slightly/non-mobile
47***
Daminozide
BASF
Basamid
Dazomet
Soil
sterilant
97.0%
<1***
50***
3.6***
Nufarm MSS
Diuron 500
FL
Diuron
Herbicide
50.0%
90-180
400
moderately mobile
36.4
Bayer Admire
Imidacloprid
Insecticide
70.0%
120
132-256**
moderately mobile
0.61
Bayer Chipco
Green
Iprodione
Herbicide
24.3%
20-160
373-1551
slightly/moderately
mobile
0.013
AgriGuard
Metazachlor
Metazachlor
Herbicide
43.1%
1-77
75***
moderately mobile
430
Syngenta
Aphox
Pirimicarb
Insecticide
50.0%
7-234
455**
moderately mobile
3
BASF Scala
Pyrimethanil
Fungicide
37.4%
7-54
265-751
slightly/moderately
mobile
0.121
 2007 Horticultural Development Council
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180***
*All data from Tomlin, 2000 except **ACP Information sheets ***Agritox database
Koc = Pesticide absorption coefficient, normalised for the amount of organic carbon
Treatment concentrations for the laboratory incubation experiments were based on the
recommended use rate of each pesticide and more specifically the recommended use rate
for either the protected crop or hardy nursery stock sectors.
In the absence of available
samples of pesticide waste to determine actual concentrations in pesticide waste a
concentration of 4 times the maximum recommended use rate was used.
This was on
the basis of a) being high enough to be easily detectable by HPLC analysis, b) broadly
representative of the concentrations of pesticides anticipated to be present in pesticide
waste and washings and c) the same as that used in previous studies (Fogg et al.,
2003a,b Fogg et al., 2004a,b,c)
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Preparation of biomix
A biobed mixture (biomix) was made up from volumetric proportions of straw (50%),
peat-free compost (25%) and sandy loam topsoil (25%) (Table 2).
This mixture was
left to compost on a concrete pad for 60 days, then macerated using a food processor,
air dried to approximately 30 - 35% w/w, and refrigerated at a 0-10 °C prior to use.
Disturbed sub-samples of biomix were re-packed into 156 cm3 volumetric tins and the
maximum water holding capacity determined by capillary rise (Hall et al., 2007).
All
studies were undertaken at 40% of maximum water holding capacity (58% water w/w).
Table 2 Top soil characteristics
% sand (2.00 – 0.0063mm
86
% silt 0.0063 – 0.002 mm
8
% clay < 0.002mm
6
Textural classification
Loamy sand
pH
5.8
Organic carbon % m/m
0.99
Residue analysis
Samples were then sent to Warwick HRI as complete sample sets for analysis so that
each compound could be analysed at one time with a freshly prepared standard.
Samples
were analysed by High Performance Liquid Chromatography (HPLC) using a Genesis C8
Column (25 cm x 4.6 cm).
Table 3 details the mobile phase, flow rates, retention
times, wavelengths and % recovery for each of the compounds.
performed at 4 mg kg-1.
The recoveries were
All samples were extracted with 50 ml acetonitrile and shaken
for 30 mins.
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Table 3 : HPLC conditions and recoveries for the 9 pesticides used in the degradation studies
Trade Name
Compound
Mobile phase
(Acetonitrile:water)
Retention
time
(mins)
Wavelength
(nm)
%
recovery
70 : 30
Flow
rate
(mL
min-1)
1.2
Syngenta
Amistar
Azoxystrobin
4.48
230
>95%
Tripart
Defensor FL
Carbendazim
60 : 40
1.2
2.93
280
74%
AgriGuard
Chlorothalonil
Nufarm MSS
Diuron 500
FL
Chlorothalonil
60 : 40
1.2
9.08
230
>95%
Diuron
60 : 40
1.2
4.90
230
>95%
Bayer Admire
Imidacloprid
60 : 40
1.2
3.13
280
>95%
Bayer Chipco
Green
Iprodione
70 : 30
1.2
5.26
230
>95%
AgriGuard
Metazachlor
Metazachlor
60 : 40
1.2
5.40
230
>95%
Syngenta
Aphox
Pirimicarb
60 : 40
1.2
4.66
230
>94%
BASF Scala
Pyrimethanil
60 : 40
1.2
6.67
280
>95%
Data
2.1.1 Pesticide degradation
Where possible the first order rate equation was fitted to the observed concentrations,
(Equation 1),
dC
  kC
dt
(Equation 1)
where C is the concentration (mg kg-1 soil), t is the time (days) and k is the
degradation rate (days-1).
The integrated form of this equation (equation 2) was fitted
 2007 Horticultural Development Council
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to non-transformed data using the least squares method in order to give the best
agreement between calculated and observed concentrations.
(Equation 2)
C(t) = C0 exp (-kt)
However, the first order rate equation is often considered unacceptable if the determination
coefficient (r2) falls below 0.7 (Beulke et al., 2001).
Where data indicated increasing
rates of degradation with time, DT50 and DT90 values were calculated using an empirical
two-parameter relationship,
(Equation 3)
S/S0 = exp{k1[1-exp(k2t)]}
where S0 and S are the concentrations of pesticide at time 0 and time t, respectively.
Microsoft Excel Solver was used to estimate parameters k1 and k2 using the least squares
method in order to give the best agreement between calculated and observed
concentrations.
The degradation data were summarised by calculating the times to 50%
degradation (DT50) and the time to 90% degradation (DT90) from the calculated
degradation curves using the relationship;
DT50 = ln(1-ln(0.5)/k1)/k2
(Equation 4)
DT90 = ln(1-ln(0.1)/k1)/k2
(Equation 5)
Experiment 1 Degradation studies for individual pesticides
Samples (25 g) of moist biomix were weighed into clear glass bottles (125 mL) fitted
with bakelite screw cap lids to provide 3 treated replicates.
The pesticides were added to
the biomix as aqueous solutions of the commercial formulations in water.
The carrier
volume was sufficient to adjust the moisture content of the biomix to 40% maximum water
holding capacity (MWHC) (58% w/w).
The actual quantity of each pesticide
 2007 Horticultural Development Council
9
administered is shown in Table 4.
The samples were then incubated at 20oC (+/-
2.0oC) with samples taken for analysis at 0, 1, 7, 14, 28 and 63 days after treatment
(DAT).
Moisture contents were checked at each sampling date up to 14 DAT, and
weekly thereafter to ensure that the soils did not dry out.
On each sampling occasion, the three replicates for each timepoint were removed from the
incubator and frozen at a minimum of -15oC prior to analysis.
 2007 Horticultural Development Council
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Table 4: Recommended application rates (N) and 4N rates for pesticides used in degradation
studies
Trade Name
Active ingredient
Recommended application
rate (N) (mg kg-1)
4N (mg kg-1)
Syngenta Amistar
Azoxystrobin
1.9
7.7
Tripart Defensor FL
Carbendazim
3.8
15.4
AgriGuard Chlorothalonil
Chlorothalonil
8.5
33.9
Nufarm MSS Diuron
500 FL
Diuron
27.7
110.8
Bayer Admire
Imidacloprid
0.96
3.8
Bayer Chipco Green
Iprodione
76.9
307.7
AgriGuard Metazachlor
Metazachlor
9.6
38.4
Syngenta Aphox
Pirimicarb
1.9
7.7
BASF Scala
Pyrimethanil
6.2
24.6
Experiment 2 Degradation studies for 9 pesticide mixtures
The degradation studies for the 9-pesticide mixture was undertaken in the same way as
those for the individual pesticides.
Additional sampling timepoints of 91 and 126 DAT
were included, to allow for a potential decrease in degradation rate by the use of a
complex mixture.
The pesticide solution was made up in the same way as for the
individual compounds with each pesticide being included at the 4N rate.
Experiment 3 Degradation of 9 pesticide mixtures in sterile and non-sterile soils
The degradation of the 9-pesticide mix experiment was repeated, this time with the
solution being added to either 25 g of biomix, as previously, or to 25 g biomix that had
been treated with BASF Basamid (Dazomet 97.0% w/w).
Basamid is a soil sterilant
used prior to planting with various fruit and vegetables, ornamentals and certain protected
crops.
The chemical is mixed with damp soil and releases Methyl isothiocyanate (MITC)
 2007 Horticultural Development Council
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gas on contact.
environment.
The gas sterilises the soil over a period of 14-28 days in a closed
All jars were sealed with parafilm after addition of the sterilant.
The sterilant was applied at the recommended application rate of 760 kg ha-1, which is
equivalent to 5.67 g kg-1, or 0.10 g per 25 g biomix.
maximum use rate (N) as opposed to 4N.
The sterilant was used at the
This was because the biomix would be
sterilised at the normal use rate and adding extra sterilant was considered unnecessary.
The samples were then incubated at 20oC (+/- 2.0oC) for 0, 1, 7, 14, 28, 63, 91
and 126 DAT.
The sampling and storage procedures for the samples were the same as
with the previous experiment, as was the analysis process.
were made.
No analyses for the sterilant
DAT 0, 1, 7 and 14 samples were vented prior to freezing.
This involved
unsealing the samples, both sterile and non-sterile, and allowing air transfer into and out
of the jar for a minimum of two minutes in a well ventilated area to allow any build up
of MITC gas to escape.
For samples that were to be incubated longer than 14 DAT, the
samples were vented on the 14th day in the same way.
The lids were then replaced but
not sealed with parafilm.
Degradation of 9 pesticide mixture in the presence and absence of plant growth regulator
This experiment has yet to be conducted.
The aim is to repeat the degradation study for
the 9-pesticide mixture, this time in the presence and absence of a plant growth
regulator, Certis B-Nine (Daminozide 85.0%).
Impact of soil sterilant on the soil microbial nitrogen content of biomix
Soil microbial nitrogen is used as an indicator of soil microbial biomass.
It is possible to
measure this following a modified version of the chloroform fumigation method of Jenkinson
& Powlson (1976) outline by Mele & Carter (1996).
The method requires that for
each soil and timepoint, there should be a control sample and a fumigated sample.
When the analysis is complete, the control sample is an indicator of the level of nitrogen
present in the soil matrix and the fumigated sample is a measure of the nitrogen present
in both the biomass of the microbial community and the soil.
 2007 Horticultural Development Council
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Therefore, to have an
indicator of the microbial biomass, it is possible to subtract the nitrogen content of the
control sample from the nitrogen content of the fumigated sample.
In this study, the requirement was to assess the level of biomass present in the untreated
biobed mixture and to see how that differed from biobed mixture that had been sterilised
with Basamid, and whether the biobed mixture recovered with time.
g) of biomix were weighed out.
Basamid.
Samples (36 x 20
Eighteen of these samples were treated with 0.08 g
As Basamid takes 14 days to take effect, the first assessment of soil nitrogen
content was conducted after 14 days incubation (20oC +/- 2 oC) of both sterile and
non-sterile soils.
After this time, all the jars were vented for two minutes in fresh air.
This was then taken as DAT 0.
6 unsterilised samples and 6 sterilised samples were
taken from the incubator and three of each were treated with 2 ml of chloroform.
The
12 jars were then sealed with parafilm and incubated for 7-10 days at 25oC (+/-2oC).
At the end of this period, the fumigated samples were unsealed and transferred to a
vacuum dessicator for 10 minutes to remove all traces of chloroform.
were then extracted with 50 ml 2 M KCl.
All the samples
The extracts were then frozen.
This
procedure will be repeated at DAT 14 and DAT 28.
A second study was also conducted which looked at the ability of the biobed to recover if
there was inclusion of fresh biobed material over time.
The experiment was set up in the
same way as previously, using 15 g of biobed mixture, instead of 20 g.
Basamid applied was reduced accordingly to 0.06 g.
The amount of
As before, the sterile and non-
sterile samples were incubated for 14 days at 20oC (+/- 2 oC) and vented on the 14th
day.
All samples were then inoculated with 5 g of biobed mixture that had been stored
as a bulk sample for 14 days at 1-4oC.
to inoculation.
This was brought to ambient temperature prior
The experiment was then continued as described above.
Results
Only the results from experiment 1 (individual pesticide degradation experiments) are
reported here, (Table 5, Figure 1, Figure 2).
With the exception of metazachlor,
azoxystrobin and imidacloprid the pattern of degradation could be fitted to first order
 2007 Horticultural Development Council
13
kinetics, (equation 2).
Data for metazachlor and azoxystrobin showed decreasing rates of
degradation time (Figure 1), even so DT90 values of 62.2 days and 193.4 days indicate
that accumulation should not be an issue.
It was not possible to calculate a DT50 or
DT90 for imidacloprid over the time scale (63 days) these experiments were conducted.
The reported DT50 for imidacloprid, applied to field soils at the maximum recommended
rate is 120 days.
It was anticipated that degradation in biomix would be quicker than in
field soils, even at 4 times the maximum recommended application rate and therefore the
experiment was conducted over the same time frame as for the other pesticides.
Experiment 1 will be repeated for imidacloprid and run over a longer timescale.
Calculated
DT50 values for each of the remaining 8 pesticides applied at 4 times the maximum
recommended rate to biomix were similar or lower than reported DT50 values for field soil
treated at the maximum recommended field rate.
 2007 Horticultural Development Council
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Table 5 : DT50 values for individual pesticides applied to biobed mixture in laboratory
incubation studies
Pesticide
(Trade name)
Active
Azoxystrobin
DT50
(days)
48
DT90
(days)
193
Syngenta
Amistar
Tripart Defensor
FL
Carbendazim
10
AgriGuard
Chlorothalonil
Nufarm MSS
Diuron 500 FL
Chlorothalonil
k deg
r2 value
(days )
k1 0.011
k2 1.360
0.98
Reported DT50
(days)*
7-56
34
0.067
1
8-32
9
29
0.078
0.98
5-36
Diuron
22
73
0.032
0.99
90-180
Bayer Admire
Imidacloprid
>63
>63
-
0.96
120
Bayer Chipco
Green
Iprodione
8
28
0.082
0.95
20-160
AgriGuard
Metazachlor
Metazachlor
14
62
k1 0.033
k2 0.690
0.99
1-77
Syngenta Aphox
Pirimicarb
9
29
0.080
0.99
7-234
BASF Scala
Pyrimethanil
11
36
0.064
1
7-54
–1
* Tomlin (2000)
Conclusions
Results from the experimental work completed to date indicate that the biobed matrix
material (biomix) is able to degrade a range of pesticides typically used by the Protected
Crop and / or Hardy Nursery stock sectors.
With the exception of imidacloprid, DT50
values for the remaining pesticides are similar or lower that the reported values for field
soil treated at concentrations 4 time lower.
More importantly, with the possible exception
of azoxystrobin, data indicated that risk of pesticides accumulating in the biobed is low.
Technology Transfer
No technology transfer activities have been carried out to date.
 2007 Horticultural Development Council
15
Concentration mg/kg
Concentration mg/kg
14
12
10
8
6
4
2
0
0
20
40
60
14
12
10
8
6
4
2
0
0
80
20
30
25
20
15
10
5
0
0
20
40
60
40
30
20
10
0
0
80
20
40
60
80
Days after treatment
(c)
(d)
8
7
6
5
4
3
2
1
0
Concentration mg/kg
Concentration mg/kg
80
50
Days after treatment
0
20
40
60
250
200
150
100
50
0
0
80
20
40
60
80
Days after treatment
Days after treatment
(e)
(f)
35
30
25
20
15
10
5
0
Concentration mg/kg
Concentration mg/kg
60
(b)
Concentration mg/kg
Concentration mg/kg
(a)
0
20
40
60
7
6
5
4
3
2
1
0
80
0
Days after treatment
(g)
40
Days after treatment
Days after treatment
20
40
60
80
Days after treatment
(h)
Figure 1 Degradation (+/-1SE) of a) azoxystrobin, b) carbendazim, c) chlorothalonil, d) diuron, e)
imidacloprid, f) iprodione, g) metazachlor and h) pirimicarb when applied to biomix at 4 times the
maximum recommended rate
 2007 Horticultural Development Council
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Concentration mg/kg
25
20
15
10
5
0
0
20
40
60
80
Days after treatment
Figure 2 Degradation (+/-1SE) of pyrimethanil when applied to biomix at 4 times the maximum
recommended rate
 2007 Horticultural Development Council
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References
Agritox http://www.inra.fr/agritox)
Beulke, S.; Brown, CD, Evaluation of methods to derive pesticide degradation
parameters for regulatory modelling.
Bio. Fert. Soils 33:558-564 (2001)
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