Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to terrestrial plants

Currently viewing:

Administrative data

toxicity to terrestrial plants: long-term
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Study period:
From 1993 to 1995
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
The test was not performed according to the standardized method and GLP. No information was available about test substance. All test parameters were not reported. The test results were not expressed specifically for Potassium sulfate but for all S fertilizer treatments. As potassic extracts is a multiconstituent substance, its toxicity to terrestrial organisms can be estimated based on the toxicity of each of its main constituent. In this study, the substance tested, potassium sulfate, is one of the main constituents of potassic extracts and therefore is used in the analogue approach. The analogue approach justification is described in the field "Any other information on results incl. tables"

Data source

Reference Type:
Cotton response to the rate and source of sulfur on a sandy coastal plain soil
Bibliographic source:
J. Prod. Agric., vol 11, n°2, 214-218

Materials and methods

Test guideline
no guideline followed
not applicable
Principles of method if other than guideline:
This study was a 3-years field test conducted in south Alabama on a Lucy loamy sand to evaluate the response of cotton to the source, rate and timing of S fertilizer applications including potassium sulfate.
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
Potassium sulfate
EC Number:
EC Name:
Potassium sulfate
Cas Number:
Molecular formula:
dipotassium sulfate
Details on test material:
- Name of test material: Potassium sulfate (18% S, 50% K2O)
- Substance type: no data
- Physical state: no data
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Purity test date: no data
- Lot/batch No.: no data
- Expiration date of the lot/batch: no data
- Stability under test conditions: no data
- Storage condition of test material: no data
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Details on properties of test surrogate or analogue material
The following data are taken from the SIDS dossier of Sulfate Category, published on UNEP (OECD, 2007)
- Melting point: 1067°C
- Boiling point: 1698°C at 1013 hPa
- Vapour pressure: Not applicable
- Water solubility: 120 g/L at 20°C
- Henry's law constant: No data
- log Pow: Not applicable
- pKa:
sulfuric acid : -3; 1.92
- Stability in water: no data
- Stability in light: no data
- pH dependence on stability: no data

In aquatic environments, the soluble portion of the substance completely dissociates into the sulfate ion (SO42-) and the potassium cation (K+) at neutral pH.

Sampling and analysis

Analytical monitoring:
Details on sampling:
Upper-most mature cotton leaves (20 per plot) were collected at early bloom for S analysis.
Leaves were dried at 60°C and ground to pass a 2 mm stainless steel screen.

Prior to initiation of the test in 1993, soil samples were collected for routine soil analysis and the determination of background levels of extractable S.
Four soil cores of 31.25 mm diameters were collected from each check plot.
Individual cores were subdivided into depth increments of 0-27.5, 27.5-45.0, 45.0-60.0, 60.0-75.0, and 75.0-90.0 cm.
For a given depth increment, samples were composited within a given plot.
The samples were also extracted with 0.5 N NH4OAc in 0.25 N CH3COOH.

Test substrate


Test organisms

other: Gossypium hirsutum L.
Plant group:
other: Eudicots
Details on test organisms:
- Common name: Cotton
- Plant family: Malvaceae
- Variety: Deltapine 90
- Source of seed: no data
- Prior seed treatment/sterilization: no data
- Historical germination of seed (germination of seed lot tested): no data
- Seed storage: no data

Study design

Test type:
not specified
Study type:
field study
Substrate type:
natural soil
Limit test:
Total exposure duration:
36 mo

Test conditions

Test temperature:
No data
5.2 – 6.1
No data
Details on test conditions:
- Testing facility: Experimental plot consisted of eight rows 30 ft in length with 3 ft between rows.
- Test container (type, material, size): not concerned
- Amount of soil: no data
- Method of seeding: the variety was seeded at a rate of 22.5 kg/ha. Planting date were 12/05/1993, 30/04/1994 and 02/05/1995.
- No. of seeds per container: no data
- No. of plants (retained after thinning): no data
- No. of replicates per treatment group: 4
- No. of replicates per control: no data
- No. of replicates per vehicle control: not concerned

The growth conditions corresponding to the natural conditions in Headland, Alabama from may 1993 to September 1995.
The average rainfall during 3 years was 717.5 mm. with a growing season in 1994 extremely wet, especially in July.


Seed cotton yields were determined at maturity by machine harvesting the two center rows from each plot.
Fiber properties evaluated included micronaire, length, length uniformity, strength, elongation, trash uniformity, and color.


- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline: not concerned
- Range finding study: no data
Nominal and measured concentrations:
Nominal concentrations: 0, 11.25, 22.5 and 45 kg/ha
All treatments received total annual applications of 102.5 kg N/ha, 68.05 kg P2O5/ha and 158.75 kg K2O/ha.
Reference substance (positive control):

Results and discussion

Effect concentrations
other: Gossypium hirsutum L.
36 mo
Dose descriptor:
Effect conc.:
22.5 kg/ha
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
other: Lint yield
Details on results:
Lint yields were increased by the rate of S, but were not affected by the source of S, the time of S application, or the interaction between source and rate. Applying 22.4 kg S/ha increased lint yields by an average of 15 to 26% depending on the year.
A linear response to S rate in 1994 was attributed to the high rainfall received in July and a probably leaching of some of the applied S in this sandy soil.
The quadratic responses observed in 1993 and 1995 were probably attributed to drought conditions.
Potassium sulfate produced slightly lower yields than ammonium sulfate and potassium magnesium sulfate.
In 1995, fiber length was increased slightly the application of S.
Fiber length was also affected by the interaction between source and rate, but there were no consistent differences among sources across rates.
Concentration of S in cotton leaves collected at mid-bloom increased with the rate of applied S during the study.
In 1994 and 1995, there was a significant interaction between rate and time of application for S concentration in leaves. Sulfur applications at early squaring resulted in higher S concentrations than preplant treatments.
Reported statistics and error estimates:
Lint yield, lint quality and leaf S analysis data were analyzed using analyses of variance and regression procedures.
Single degree of freedom contrasts were used to evaluate linear and quadratic responses for significant responses to S Rate.
Fisher’s protected LSD’s (P=< 0.10) were used for mean separation of planned comparisons.

Any other information on results incl. tables

Analogue approach justification

Potassic extracts is a multiconstituent substance. As its main constituents are simple inorganic salts (i.e. potassium sulfate, sodium sulfate and calcium sulfate), in aquatic environment, the soluble portion of each constituent completely dissociates into the sulfate ion (SO42 -) and the corresponding cations: potassium (K+), sodium (Na+) and calcium (Ca2 +) at neutral pH.

The physico-chemical properties of the main constituents are similar and they are not harmful to the aquatic organisms tested (rem: calcium sulfate is less soluble than the other constituents of the potassic extracts, but its water solubility is sufficiently high to determine the absence of toxicity to aquatic organisms at concentration higher than 100 mg/L, showing absence of harmful effect to the tested organisms, as it is also showed for the other constituents).

Therefore, potassium sulfate, along with the other salts present in the potassic extracts, can be used in a read-across approach to assess the terrestrial toxicity of the multiconstituent substance.

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Executive summary:

The effect of different sources, rates and timing of S fertilizer applications including potassium sulfate on the lint yield of Gossypium hirsutum L. was studied during 3 years, from 1993 to 1995, in a field test in Headland, Alabama at nominal concentrations of 0, 11.25, 22.5 and 45 kg S /ha.


The growth medium used was Lucy loamy sandwith different S fertilizer treatments. All treatments received total annual applications of158.75 kg K2O/ha.


The 3 years-NOEC for lint yield was 22.5 kg S/ha.


A positive yield response to S rate was obtained during all 3 years of this test.

Results of this test suggest that Gossypium hirsutum L. produced on sady coastal plain soils with low S may require annual applications of 22. 5 kg S /ha to ensure high yields.

The average increase in lint yield at this rate of S was 21%.

Sulfur on these soils should be applied preplant although delaying application to first square was acceptable.

Effects of S fertilization on lint quality were minimal.

Results also suggest that differences among commercial fertilizer S sources in influencing lint production will be minimal.


Result synopsis

Test organism: Gossypium hirsutum L.

Test type:Field study

3-years-NOEC: 22.5 kg S/ha

Endpoint(s) Effected:lint yield.