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Toxicity to soil microorganisms

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Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 Nov - 12 Dec 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
BBA Part VI, 1-1
Version / remarks:
March 1990, 2nd edition
Qualifier:
according to guideline
Guideline:
other: ISO/DIS 1036-6:1992, Soil Quality - Sampling - Part 6: Guidance on the Collection, Handling and Storage of Soil for the Assessment of Aerobic Microbial Processes in the Laboratory
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 216 (Soil Microorganisms: Nitrogen Transformation Test)
GLP compliance:
yes (incl. QA statement)
Remarks:
Ministerium für Umwelt, Raumordnung und Landwirtschaft des Landes Nordrhein-Westfalen, Düsseldorf, Germany
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
AMENDMENT OF SOIL
- Type of organic substrate: lucerne-grassgreen-meal

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: Sieved soil (2 mm) was treated with either 10 g ground quartz sand/kg dry wt soil (control) or a mixture of quartz sand and test item (0.81 mg or 8.05 mg/kg dry wt soil). The samples were mixed with pulverized lucerne-grass-green meal (5000 mg/kg dry wt soil) and quartz sand in 3 liter polyethylene containers by rolling on a gyrowheel mixer (Elte 650, J. Engelsmann AG, Ludwigshafen, Germany) for 15 min at 50 rpm. In separate studies it was determined that mixing substances into soils as described gives a homogeneous and reproducible distribution (Blumenstock, 1989, Bayer AG, Report No. BSI/70889). Since the soils were not extracted and analyzed, values given for the active ingredients are nominal.
Test organisms (inoculum):
soil
Total exposure duration:
28 d
Test temperature:
20 ± 2 °C
Moisture:
about 40% water capacity
Details on test conditions:
TEST SYSTEM
- Testing facility: Bayer AG, Crop Protection Development, Institute for Environment Biology, Leverkusen, Germany
- Test container (type, material, size): 500 mL brown glass bottles
- Amount of soil: 250 g dw
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOIL INCUBATION
- Method: After mixing, soil samples equivalent to 250 g dry wt were poured into 500 mL brown glass bottles and these were closed with parafilm. Each bottle was marked with an identification number and the quantity of product added to the soil. Soils were held in the dark.

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): Soil 1: Field plot F on the Bayer AG's experimental farm Laacherhof, Germany; Soil 2: Field plot am Hohenseh 4a on the Bayer AG's experimental farm Höfchen, Germany
- History of site:
Soil #1: Plant protection chemicals have not been used on this field since 1981. Grass was planted in 1987, summer wheat in 1988, winter rye in 1988/89, winter barley in 1989/90, winter wheat in 1990/91, grass in Spring 1991, summer wheat in 1993, winter rye in 1993/1994 and winter barley in 1994/1995. At the beginning of the experiments, Soil 1 held 0.62 mg NH4-N- and 8.17 mg NO3-N/kg dry wt soil.
Soil #2: Plant protection chemicals have not been used on this field since 1988. Since 1985, crop rotation has been as follows: 1985/86, summer barley; 1986/87, winter barley; 1987/88, oats; Fall 1988, winter barley ploughed up, perennial ryegrass planted. The last fertilizer was applied in the Fall of 1988. At the beginning of the experiments, Soil 2 held 1.26 mg NH4-N- and 45.36 mg NO3-N/kg dry wt soil.
- Treatments with pesticides or fertilizers: see above
- Soil texture: Particle size distributions were determined as described in DIN 19682 (1973: Deutsche Normen: Bodenuntersuchungsverfahren im Landwirtschaftlichen Wasserbau, Felduntersuchungen, Ermittlung der Bodenart)
- % sand: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- % silt: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- % clay: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- Soil taxonomic classification: Soil #1: loamy sand; Soil #2: loamy silt
- pH: The pH-values were determined by stirring 10 g dry wt soil with 50 ml IN KC1 and measuring immediately with a pH electrode.
- Maximum water holding capacity (in % dry weigth): about 40%
- Pretreatment of soil: Soils were collected on 15 Oct. 1996. They were passed through a 2 mm sieve and stored until used, as described in the BBA Guideline (1990: Guidelines for the Official Testing of Plant Protectants, Part VI, 1-1, Influence on the Activity of the Soil Microflora, BBA, Braunschweig, Germany, Macrh 1990, 2nd ed.) and ISO/DIS 1036-6 (1992: Soil Quality - Sampling - Part 6: Guidance on the Collection, Handling and Storage of Soil for the Assessment of Aerobic Microbial Processes in the Laboratory)
- Initial microbial biomass: Soil #1: 173 mg microbial C/ kg dw soil; Soil #2: 1456 mg microbial C/ kg dw soil. The carbon content of the metabolically active microbial biomass in each soil was determined at the start of each experiment as described by Anderson and Domsch (1978).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): extracts analyzed for their content of ammonium-N, nitrite-N, and nitrate-N plus nitrite-N after 14 and 28 days.
Nominal and measured concentrations:
control, 0.81, and 8.05 mg/kg dw soil (nominal)
Reference substance (positive control):
yes
Remarks:
ARETIT FLÜSSIG®
Key result
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 8.05 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Key result
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
> 8.05 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
nitrate formation rate
Details on results:
The study resulted in no effects observed and no effect values were reported. EC10 and EC50 values added here are based on the highest test concentration causing no effects.

Table 1: pH values (1 N KCI) in control and treated samples of Soil #1 after 0 and 28 days of storage at 20 ± 2 °C and 40% water capacity (averages from 3 soil samples)

Days after treatment

Test item/kg dry wt soil

 

0 mg

0.81 mg

8.05 mg

0

6.1

6.0

6.0

28

6.4

6.4

6.4

 

Table 2: pH values (1 N KCI) in control and treated samples of Soil #2 after 0 and 28 days of storage at 20 ± 2 °C and 40 % water capacity (averages from 3 soil samples)

Days after treatment

Test item/kg dry wt soil

 

0 mg

0.81 mg

8.05 mg

0

7.1

7.1

7.1

28

7.3

7.2

7.2

 

Table 3: Nitrogen mineralization in Soil #1 after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg dry wt soil) (averages from 3 soil samples).

Days after treatment

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg Nitrogen/kg dw soil (averages and standard deviations from 3 soil samples)

Ammonium

Nitrate

Ammonium

Nitrate

Ammonium

Nitrate

0

2.46 ± 0.04

9.26 ± 0.16

2.42 ± 0.06

9.27 ± 0.03

2.41 ± 0.08

9.40 ± 0.10

14

1.13 ± 0.08

10.97 ± 0.22

1.09 ± 0.22

10.07 ± 0.59

0.99 ± 0.11

12.25 ± 0.54*

28

1.77 ± 0.60

24.82 ± 1.51

1.29 ± 0.48

23.92 ± 2.75

1.47 ± 0.72

25.72 ± 0.32

* Significant difference between treated and untreated soil samples (t-test with 5% probability level)

Table 4: Nitrogen mineralization in Soil #2 after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg dry wt soil) (averages from 3 soil samples).

Days after treatment

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg Nitrogen/kg dw soil

Ammonium

Nitrate

Ammonium

Nitrate

Ammonium

Nitrate

0

2.62 ± 0.09

45.09 ± 0.78

2.66 ± 0.14

44.35 ± 0.52

2.63 ± 0.10

45.15 ± 0.20

14

2.83 ± 2.46

49.95 ± 6.21

3.16 ± 1.89

56.14 ± 3.08

2.28 ± 2.44

50.40 ± 11.40

28

1.22 ± 0.12

66.26 ± 6.62

1.17 ± 0.05

72.66 ± 2.41

1.14 ± 0.05

68.19 ± 7.98

Table 5: Rates of nitrogen turnover in Soil #1 after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg dry wt soil).

Days after treatment

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg Nitrogen/kg dw soil

Ammonium

Nitrate

Ammonium

Nitrate

Ammonium

Nitrate

0 - 14

-1.33

1.71

-1.33

0.80

-1.42

2.84

14 - 28

0.64

13.86

0.20

13.85

0.49

13.47

 

Table 6: Rates of nitrogen turnover in Soil #2 after treatment with the test item and addition of lucerne-grass-green meal (5000 mg/kg dry wt soil).

Days after treatment

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg Nitrogen/kg dw soil

Ammonium

Nitrate

Ammonium

Nitrate

Ammonium

Nitrate

0 - 14

0.21

4.86

0.50

11.79

-0.34

5.26

14 - 28

-1.61

16.31

-2.00

16.53

-1.15

17.79

 

Overall result:

The test item did not cause a change in soil pH.

Trace quantities of nitrite were found in all samples (control and treated samples).

During 28-day experiments, in soils amended with lucerne-grass-green-meal (5000 mg/kg), it was found that 0.81 mg test item/kg dry wt soil (equivalent to 0.6 kg a.i. product/ha) and the 10-fold overdose of the compound (8.05 mg/kg dry wt soil equivalent to 6.0 kg a.i. product/ha) had no meaningful influence on the turnover of nitrogen in either a loamy sand or a loamy silt.

Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 Nov - 12 Dec 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
BBA Part VI, 1-1
Version / remarks:
March 1990, 2nd edition
Qualifier:
according to guideline
Guideline:
other: ISO/DIS 1036-6:1992, Soil Quality - Sampling - Part 6: Guidance on the Collection, Handling and Storage of Soil for the Assessment of Aerobic Microbial Processes in the Laboratory
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 217 (Soil Microorganisms: Carbon Transformation Test)
GLP compliance:
yes (incl. QA statement)
Remarks:
Ministerium für Umwelt, Raumordnung und Landwirtschaft des Landes Nordrhein-Westfalen, Düsseldorf, Germany
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: Sieved soil was treated with either 10 g ground quartz sand/kg dry wt soil (control) or a mixture of quartz sand and test item (0.81 mg or 8.05 mg/kg dry wt soil). The samples were mixed in 3 liter polyethylene containers by rolling on a gyrowheel mixer (Elte 650, J. Engelsmann AG, Ludwigshafen, Germany) for 15 min at 50 rpm. In separate studies it was determined that mixing substances into soils as described gives a homogeneous and reproducible distribution (Blumenstock, 1989, Bayer AG, Report No. BSI/70889). Since the soils were not extracted and analyzed, values given for the active ingredients are nominal.
Test organisms (inoculum):
soil
Total exposure duration:
28 d
Test temperature:
20 ± 2 °C
Moisture:
about 40 % water capacity
Details on test conditions:
TEST SYSTEM
- Testing facility: Bayer AG, Crop Protection Development, Institute for Environment Biology, Leverkusen, Germany
- Test container (type, material, size): 1 L clear glass jars
- Amount of soil: 750 g dw
- No. of replicates per concentration: 3
- No. of replicates per control: 3

SOIL INCUBATION
- Method: After mixing, soil samples equivalent to 750 g dry wt were poured into 1 liter clear glass jars and these were covered with clear glass lids. The lids were loose enough to allow air exchange, but tight enough to slow evaporation of moisture. Each jar was marked with an identification number and the quantity of product added to the soil. Soils were held in the dark.

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographical reference of sampling site (latitude, longitude): Soil 1: Field plot F on the Bayer AG's experimental farm Laacherhof, Germany; Soil 2: Field plot am Hohenseh 4a on the Bayer AG's experimental farm Höfchen, Germany
- History of site:
Soil #1: Plant protection chemicals have not been used on this field since 1981. Grass was planted in 1987, summer wheat in 1988, winter rye in 1988/89, winter barley in 1989/90, winter wheat in 1990/91, grass in Spring 1991, summer wheat in 1993, winter rye in 1993/1994 and winter barley in 1994/1995. At the beginning of the experiments, Soil 1 held 0.62 mg NH4-N- and 8.17 mg NO3-N/kg dry wt soil.
Soil #2: Plant protection chemicals have not been used on this field since 1988. Since 1985, crop rotation has been as follows: 1985/86, summer barley; 1986/87, winter barley; 1987/88, oats; Fall 1988, winter barley ploughed up, perennial ryegrass planted. The last fertilizer was applied in the Fall of 1988. At the beginning of the experiments, Soil 2 held 1.26 mg NH4-N- and 45.36 mg NO3-N/kg dry wt soil.
- Treatments with pesticides or fertilizers: see above
- Soil texture: Particle size distributions were determined as described in DIN 19682 (1973: Deutsche Normen: Bodenuntersuchungsverfahren im Landwirtschaftlichen Wasserbau, Felduntersuchungen, Ermittlung der Bodenart)
- % sand: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- % silt: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- % clay: see Table 1 & 2 under "Any other information on materials and methods incl. tables" below
- Soil taxonomic classification: Soil #1: loamy sand; Soil #2: loamy silt
- pH: The pH-values were determined by stirring 10 g dry wt soil with 50 mL in KCl and measuring immediately with a pH electrode.
- Maximum water holding capacity (in % dry weigth): about 40%
- Pretreatment of soil: Soils were collected on 15 Oct. 1996. They were passed through a 2 mm sieve and stored until used, as described in the BBA Guideline (1990: Guidelines for the Official Testing of Plant Protectants, Part VI, 1-1, Influence on the Activity of the Soil Microflora, BBA, Braunschweig, Germany, Macrh 1990, 2nd ed.) and ISO/DIS 1036-6 (1992: Soil Quality - Sampling - Part 6: Guidance on the Collection, Handling and Storage of Soil for the Assessment of Aerobic Microbial Processes in the Laboratory)
- Initial microbial biomass: Soil #1: 173 mg microbial C/kg dw soil; Soil #2: 1456 mg microbial C/kg dw soil. The carbon content of the metabolically active microbial biomass in each soil was determined at the start of each experiment as described by Anderson and Domsch (1978).

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): extracts analyzed for their CO2 content on day 0 (within 3 hours after treatment), and on days 14 and 28 of incubation.
Nominal and measured concentrations:
control, 0.81, and 8.05 mg/kg dw soil (nominal)
Reference substance (positive control):
yes
Remarks:
ARETIT FLÜSSIG®
Key result
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 8.05 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
respiration rate
Key result
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
> 8.05 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
respiration rate
Details on results:
The study resulted in no effects observed and no effect values were reported. EC10 and EC50 values added here are based on the highest test concentration causing no effects.

Table 1: pH values (1 N KCI) in control and treated samples of Soil #1 after 0 and 28 days of storage at 20 ± 2 °C and 40% water capacity (averages from 3 soil samples)

Days after treatment

Test item/kg dry wt soil

 

0 mg

0.81 mg

8.05 mg

0

6.0

6.0

6.0

28

6.0

6.0

6.0

 

Table 2: pH values (1 N KCI) in control and treated samples of Soil #2 after 0 and 28 days of storage at 20 ± 2 °C and 40 % water capacity (averages from 3 soil samples)

Days after treatment

Test item/kg dry wt soil

 

0 mg

0.81 mg

8.05 mg

0

7.0

7.0

7.0

28

7.1

7.1

7.1

 

Table 3: Respiration in Soil #1 immediately (day 0) after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages (AV) and standard deviations (SD) from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

1

7.85

0.30

7.75

0.00

7.87

0.19

2

8.02

0.08

8.14

0.12

8.10

0.12

3

8.61

0.10

8.48

0.23

8.57

0.28

4

8.99

0.13

9.05

0.18

9.18

0.12

5

10.00

0.11

10.07

0.29

10.32

0.22

6

11.02

0.25

11.17

0.33

11.50

0.23

7

12.42

0.16

12.60

0.33

13.06

0.22

8

14.29

0.12

14.48

0.49

15.12

0.39

9

16.44

0.17

16.77

0.54

17.39

0.50

10

19.23

0.17

19.66

0.69

20.55

0.92

11

23.00

0.12

23.53

0.93

24.56

0.80

12

28.30

0.10

28.84

1.13

30.05

1.09

Sum

168.17

 

170.53

 

176.28

 

% of control

100

101

105

 

Table 4: Respiration in Soil #1 14 days after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages and standard deviations from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

2

7.37

0.11

7.22

0.05

6.92

0.04

3

7.19

0.12

7.24

0.00

6.99

0.08

4

7.38

0.06

7.37

0.10

7.13

0.01

5

7.66

0.10

7.75

0.07

7.52

0.06

6

8.07

0.06

8.21

0.11

7.99

0.19

7

8.54

0.12

8.74

0.12

8.70

0.07

8

9.31

0.11

9.60

0.07

9.46

0.06

9

10.29

0.11

10.51

0.21

10.47

0.17

10

11.38

0.18

11.74

0.27

11.67

0.19

11

13.01

0.16

13.36

0.34

13.49

0.27

12

14.69

0.11

15.22

0.38

15.47

0.75

13

17.36

0.12

18.19

0.64

18.34

0.60

Sum

122.25

 

125.15

 

124.14

 

% of control

100

102

102

 

Table 5: Respiration in Soil #1 28 days after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages and standard deviations from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

2

6.85

0.07

6.92

0.10

6.74

0.25

3

6.69

0.01

6.76

0.14

6.47

0.19

4

6.45

0.05

6.62

0.05

6.19

0.13

5

6.67

0.07

6.83

0.06

6.41

0.12

6

6.85

0.06

7.02

0.10

6.57

0.18

7

7.25

0.11

7.56

0.01

6.88

0.14

8

7.53

0.05

7.81

0.12

7.21

0.16

9

8.11

0.21

8.45

0.13

7.67

0.22

10

8.85

0.20

9.31

0.22

8.39

0.17

11

9.75

0.14

10.42

0.17

9.31

0.16

12

10.78

0.26

11.60

0.27

10.11

0.24

13

12.12

0.16

13.11

0.29

11.36

0.27

Sum

97.90

 

102.39

 

93.30

 

% of control

100

105

95

 

Table 6: Respiration in Soil #1 immediately (day 0) after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages (AV) and standard deviations (SD) from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

1

70.72

0.94

68.81

1.56

67.35

0.60

2

66.92

0.83

65.11

1.24

65.02

0.07

3

66.18

0.87

64.50

1.23

64.58

0.12

4

66.50

0.75

64.69

0.95

65.13

0.36

5

67.77

0.98

66.50

1.19

67.49

0.70

6

70.60

1.41

68.93

0.70

70.69

0.87

7

74.85

1.71

72.88

0.98

75.08

0.56

8

79.41

1.00

77.45

0.72

80.36

1.58

9

85.15

1.21

82.81

1.27

86.20

2.25

10

91.49

2.50

89.36

1.17

94.58

3.01

11

99.46

1.47

96.95

1.57

103.02

3.43

12

108.72

2.33

106.92

0.89

114.21

3.49

Sum

947.76

 

924.90

 

953.73

 

% of control

100

98

101

 

Table 7: Respiration in Soil #1 14 days after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages and standard deviations from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

2

64.41

0.94

62.35

1.49

60.74

0.50

3

59.47

0.80

57.61

1.28

56.65

0.49

4

57.50

1.07

56.15

0.96

55.63

0.51

5

57.48

0.83

55.65

0.97

55.47

0.62

6

58.08

1.04

56.17

0.87

56.92

0.82

7

59.64

1.04

57.90

0.84

59.43

1.17

8

62.30

1.40

60.85

0.97

62.89

1.66

9

64.88

1.37

63.61

0.70

66.71

1.64

10

68.27

1.06*

67.70

1.16

71.44

2.33

11

74.39

1.18

72.52

1.14

77.71

2.81

12

80.12

1.78

77.89

0.68

85.04

3.77

13

87.53

1.48

84.48

1.23

93.40

4.11

Sum

794.06

 

772.87

 

802.02

 

% of control

100 %

97%

101%

* Averages (AV) and standard deviations (SD) from 2 soil samples

Table 8: Respiration in Soil #1 28 days after treatment with the test item and addition of 3000 mg glucose/kg dry wt soil) (averages and standard deviations from 3 soil samples).

Hours after addition of glucose

0 mg

test item/ kg dw soil

0.81 mg

test item/ kg dw soil

8.05

mg test item/ kg dw soil

mg CO2/hour/kg dw soil

AV

± SD

AV

± SD

AV

± SD

2

57.75

1.02

54.50

1.35

53.43

0.46

3

53.45

0.58

51.27

1.28

51.05

0.65

4

52.07

0.54

49.41

0.84

49.56

0.82

5

51.50

0.83

49.00

1.22

49.63

0.67

6

52.16

0.77

49.91

0.80

50.86

0.89

7

53.49

0.86

50.90

1.26

52.25

1.17

8

55.47

0.82

53.11

1.15

54.39

1.44

9

57.69

0.86

55.25

1.15

57.12

1.37

10

61.03

1.25

58.47

0.99

61.13

2.05

11

64.93

1.26

62.09

1.08

65.59

2.78

12

70.09

1.13

66.95

1.20

70.51

5.00

13

76.35

0.95

72.92

1.10

78.58

4.21

Sum

705.98

 

673.76

 

694.12

 

% of control

100 %

95%

98

 

Overall result:

The test item did not cause a change in soil pH.

During the 28-day experiments, 0.81 mg product/kg dry wt soil (0.6 kg a.i. product/ha) and 8.05 mg product/kg dry wt soil (6.0 kg a.i. product/ha) had no meaningful influence on respiration after adding glucose to the loamy sand or the loamy silt.

Description of key information

EC50 (28 d) > 8.05 mg/kg soil dw (nominal, similar to OECD 216 & 217, nitrogen & carbon transformation)

EC10 (28 d) > 8.05 mg/kg soil dw (nominal, similar to OECD 216 & 217, nitrogen & carbon transformation)

Key value for chemical safety assessment

Long-term EC10 or NOEC for soil microorganisms:
8.05 mg/kg soil dw

Additional information

Two studies are available investigating the toxicity of the test substance to soil microorganisms. One study addresses the influence of the test item on nitrogen transformation in soils (1997a), the second study investigated the influence on carbon transformation (1997b). Both studies were conducted according to GLP and followed the principles of the "Guidelines for the Official Testing of Plant Protectants, Part VI, 1-1, Influence on the Activity of the Soil Microflora" (BBA Braunschweig, Germany, March 1990, 2nd ed.). This guideline is equivalent to OECD guidelines 216 and 217 for nitrogen transformation and carbon transformation, respectively. In the first study (1997a) the influence of 0.81 mg and 8.05 mg test item/kg dry wt soil on nitrogen mineralization in two agricultural soils, i.e. a loamy sand (0.8% org. C, pH (KCl) 6.1) and a loamy silt (2.3% org. C, pH (KCl) 7.1) was tested. The test lasted 28-days and soils were amended with lucerne-grass-green-meal. Both doses, the lower and the 10-fold overdose, had no meaningful influence on the turnover of nitrogen in either soil. Thus, the test item is regarded as having no significant influence on nitrogen transformation and an EC10 (28 d) of > 8.05 mg/kg soil dw and an EC50 (28 d) > 8.05 mg/kg soil dw were derived. The same effect values were determined in the carbon transformation test (1997b), using the same concentrations of test item, as well as the same two soil types. During the 28-day experiments the test substance had no influence on soil respiration after the addition of glucose to both of the test soils. Thus, the test item is regarded as having no significant influence on the degradation of organic carbon in soils.