Registration Dossier

Administrative data

Endpoint:
toxicity to soil microorganisms
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Published in peer reviewed literature, minor restrictions in design and/or reporting but otherwise adequate for assessment

Data source

Reference
Reference Type:
publication
Title:
Inhibition of nitrification in soil by heterocyclic nitrogen compounds
Author:
McCarty and Bremmer
Year:
1989
Bibliographic source:
Biol. Fertil. Soils ( 1989) 8 :204- 211

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The relationship between the structures of diverse heterocyclic nitrogen (N) compounds and the effectiveness of these compounds for the inhibition of nitrification in soil was studied by determining the effects of different amounts of substituted heterocyclic N compounds on the production of (NO2- + NO3- )-N in soils incubated at 25 °C for 21 days after treatment with ammonium sulfate.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
2-methylpyridine
EC Number:
203-643-7
EC Name:
2-methylpyridine
Cas Number:
109-06-8
Molecular formula:
C6H7N
IUPAC Name:
2-methylpyridine
Details on test material:
- Name of test material (as cited in study report): 2-Picoline

Test organisms

Test organisms (inoculum):
soil

Study design

Total exposure duration:
21 d

Test conditions

Test temperature:
25°C
Details on test conditions:
SOILS
Harps (typic Calciaquoll), Webster (typic Haplaquoll), and Storden (Typic Udorthent). Surface (0-15 cm) samples of Iowa soils were selected to obtain a range in pH (6.1-8.1), texture (9%-60% sand, 12%-49% silt, 28%-42% clay), organic-C content (1.2%-4.2%), and CaCO3 equivalent (0%-4.1%).

METHOD
Before use, each sample was air-dried and crushed to pass through a 2-mm screen. Twenty-gram samples of soil were placed in 25 x 200 mm test tubes and treated with 6 mL water containing 4 mg N as (NH4)2SO4 and 0, 0.2, 2.0, or 10.0 μmol test compound. The test tubes were then placed unsealed in an incubator maintained at 25 °C. The amount of water lost from the soil samples during the incubation was measured gravimetrically at 5-day intervals and was replaced if it exceeded 1 mL. After 21 days, of test tubes were removed from the incubator, and their triplicate contents were analyzed for (NH4+)-N, (NO2-)-N, and (NO3-)-N as described by Bremner and Keeney (1966). The amount of (NO3- + NO2-)-N produced during the incubation was calculated from the results of analyses for (NO3- + NO2-)-N before and after the incubation, and the percentage inhibition of nitrification by the test compound was calculated from (C-T)/Cx100, where T is the amount (NO3- + NO2-)-N produced in the soil sample treated with the test compound and Cis the amount (NO3- + NO2-)-N produced by the control sample (no test compound added). None of the incubated soil samples contained more than 1μg (NO2-)-N g-1 of soil, and no (NH4+)-N was detected after incubation for 21 days of the (NH4)2SO4-amended soil samples that had not been treated with a test compound.
Nominal and measured concentrations:
- Nominal concentrations: 0.01, 0.10 and 0.50 µmol/g soil

Results and discussion

Any other information on results incl. tables

Effect of 2-picoline on nitrification of ammonium in soil

Test conc. (µmol/g)

% inhibition of nitrification per soil*

 -

Harps

Webster

Storden

0.01

0

0

7

0.10

0

1

11

0.50

2

3

21

* Least significant difference (0.05) = 6.6

Applicant's summary and conclusion