Cyanamide

Toxicity to soil microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

BBA Part VI, 1-1

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

No sampling

Vehicle:

no

Details on preparation and application of test substrate:

The test susbtance in two different concentrations was applied to sandy soil amended with Lucerne meal and to loamy soil amended with Lucerne meal.

Test organisms (inoculum):

soil

Total exposure duration:

76 d

Test temperature:

Not indicated

Moisture:

Not indicated

Details on test conditions:

The effects of ALZODEF (a 49 % (w/w) aqueous solution of cyanamide) on soil microbial respiration (carbon mineralisation) and nitrogen transformation (ammonification and nitrification) were examined using a sandy soil and a loamy soil in a laboratory study. The test contained 3 replicates (nitrogen transformation) and 6 replicates (carbon mineralisation) of each treatment group: unamended soil, soil amended with Lucerne mean and soil amended with Lucerne meal and treated with a 49 % (w/w) aqueous solution of cyanamide at two rates: 40 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 19.6 kg cyanamide/ha (maximum recommended annual application rate of 20 L of a 49 % (w/w) aqueous solution of cyanamide) and 200 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 98 kg cyanamide/ha (5-times the maximum recommended annual application rate of 20 L 49 % (w/w) aqueous solution of cyanamide). Production of carbon dioxide by soil microbes and concentrations of ammonium, nitrate, and nitrite were determined periodically throughout the study.

Nominal and measured concentrations:

49 % (w/w) aqueous solution of cyanamide at two rates: 40 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 19.6 kg cyanamide/ha (maximum recommended annual application rate of 20 L of a 49 % (w/w) aqueous solution of cyanamide) and 200 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 98 kg cyanamide/ha (5-times the maximum recommended annual application rate of 20 L 49 % (w/w) aqueous solution of cyanamide)

Reference substance (positive control):

no

Key result

Duration:

76 d

Dose descriptor:

other: Deviation in respiration (compare to the control at the end of the study)

Effect conc.:

< 25 other: %.

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

respiration rate

Remarks on result:

other: The result is obtained following an application rate of 19.8 kg cyanamide/ha (maximum recommended field rate) and following an application rate of 98 kg cyanamide/ha (5-times the max. recommended field rate) to sandy soil as well as to loamy soil.

Key result

Duration:

97 d

Dose descriptor:

other: Deviation in nitrate and nitrite levels (compare to the control at the end of the study)

Effect conc.:

< 25 other: %

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

nitrate formation rate

Remarks on result:

other: The result is obtained following an application rate of 19.8 kg cyanamide/ha (maximum recommended field rate) and following an application rate of 98 kg cyanamide/ha (5-times the max. recommended field rate) to sandy soil as well as to loamy soil.

Details on results:

Deviations in the ammonium and nitrate/nitrite levels and respiration rate between control soil and soil treated with a 49 % (w/w) aqueous solution of cyanamide were < 25 % at the end of the study.

Results with reference substance (positive control):

No reference substrate

Reported statistics and error estimates:

Not applicable

Summary of effects of a 49 % (w/w) aqueous solution of cyanamide on ammonium and nitrate levels and respiration in sandy soil amended withm Lucerne meal:

Day	Deviation in ammonium levels (%)^a	Deviation in nitrate and nitrite levels (%)^a	Deviation in respiration (%)^a
Application rate: 19.8 kg cyanamide/ha (maximum recommended field rate)
7	4.9	-4.5	-
14	33.5	-18.2	3.2
21	28.3	-4.8	-
28	-11.3	1.8	-21.9
42	6.6	7.5	-
76	-1.1	-0.5	-
Application rate: 98 kg cyanamide/ha (5-times the max. recommended field rate)
7	2.4	-23.0	-
14	27.8	-6.2	34.5
21	45.0	-39.5	-
28	77.3	-37.3	-8.8
42	72.4	-23.8	-
76	2.6	1.7	-

a            % Deviation: [(measured parameter in control soil / measured parameter in treated soil) –1] x 100

-    not determined

Summary of effects of a 49 % (w/w) aqueous solution of cyanamide on ammonium and nitrate levels and respiration in a loamy soil amended withmeal:

Day	Deviation in ammonium levels (%)^a	Deviation in nitrate and nitrite levels (%)^a	Deviation in respiration (%)^a
Application rate: 19.8 kg cyanamide/ha (maximum recommended field rate)
7	-1.7	0.0	-
14	-8.7	6.0	-17.1
21	10.1	-5.9	-
28	-0.6	-4.9	-2.7
42	24.7	11.5	-
76	2.6	-4.2	-
Application rate: 98 kg cyanamide/ha (5-times the max. recommended field rate)
7	136.8	-47.1	-
14	222.7	-35.7	-22.4
21	31.0	-16.8	-
28	-2.9	1.9	7.1
42	3.8	8.6	-
76	-7.0	5.1	-

a   % Deviation: [(measured parameter in control soil / measured parameter in treated soil) –1] x 100

 

Validity criteria fulfilled:

yes

Conclusions:

Deviation in the rates of nitrogen transformation and respiration were < 25 % at the end of the study. Under anticipated conditions of field use, cyanamide is categorised as having low risk to soil microflora.

Executive summary:

The effects of ALZODEF (a 49 % (w/w) aqueous solution of cyanamide) on soil microbial respiration (carbon mineralisation) and nitrogen transformation (ammonification and nitrification) were examined using a sandy soil and a loamy soil in a laboratory study. The test contained 3 replicates (nitrogen transformation) and 6 replicates (carbon mineralisation) of each treatment group: unamended soil, soil amended with Lucerne mean and soil amended with Lucerne meal and treated with a 49 % (w/w) aqueous solution of cyanamide at two rates: 40 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 19.6 kg cyanamide/ha (maximum recommended annual application rate of 20 L of a 49 % (w/w) aqueous solution of cyanamide) and 200 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 98 kg cyanamide/ha (5-times the maximum recommended annual application rate of 20 L 49 % (w/w) aqueous solution of cyanamide). Production of carbon dioxide by soil microbes and concentrations of ammonium, nitrate, and nitrite were determined periodically throughout the study.

Deviations in the ammonium and nitrate/nitrite levels and respiration rate between control soil and soil treated with a 49 % (w/w) aqueous solution of cyanamide were < 25 % at the end of the study. As the deviation is not higher than 25% for both examined parameters, it can be concluded that cyanamide has a low risk to soil microflora (under anticipated conditions of field use).

Description of key information

From the results of two soil microflora tests (soil respiration test and nitrogen transformation) performed in two available studies, it can be concluded that the use of cyanamide (around 20 kg ai/ha and the

5-fold thereof (100 kg ai/ha)) is safe for soil non-target microorganisms as the results of both tests in both studies were practically not higher than 25% of the control.

Additional information

The effects of cyanamide (49% or 51.1% (w/w) aqueous solution of cyanamide) on soil microorganisms were examined in two studies. In the key study (Schönborn, 1990) the effects of ALZODEF (a 49 % (w/w) aqueous solution of cyanamide) on soil microbial respiration (carbon mineralisation) and nitrogen transformation (ammonification and nitrification) were examined using a sandy soil and a loamy soil in a laboratory study. The test contained 3 replicates (nitrogen transformation) and 6 replicates (carbon mineralisation) of each treatment group: unamended soil, soil amended with Lucerne mean and soil amended with Lucerne meal and treated with a 49 % (w/w) aqueous solution of cyanamide at two rates: 40 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 19.6 kg cyanamide/ha (maximum recommended annual application rate of 20 L of a 49 % (w/w) aqueous solution of cyanamide) and 200 L of a 49 % (w/w) aqueous solution of cyanamide/ha equivalent to 98 kg cyanamide/ha (5-times the maximum recommended annual application rate of 20 L 49 % (w/w) aqueous solution of cyanamide). Production of carbon dioxide by soil microbes and concentrations of ammonium, nitrate, and nitrite were determined periodically throughout the study.

Deviations in the ammonium and nitrate/nitrite levels and respiration rate between control soil and soil treated with a 49 % (w/w) aqueous solution of cyanamide were < 25 % at the end of the study. As the deviation is not higher than 25% for both examined parameters, it can be concluded that cyanamide has a low risk to soil microflora (under anticipated conditions of field use).

Similar results were obtained in the supporting study (Reis, 2002), In the carbon transformation test (soil respiration test) deviations from control were less than 25% in the end of the exposure period at both application rates (20 kg ai/ha and the 5-fold thereof (100 kg ai/ha)), indicating that the test substance induce no long – term effect (to soil microorganisms).

In the nitrogen transformation test deviations from control were less than 25% in the lower concentration rate but more than 25% in the higher test concentration at the end of the test. The deviation can be fully explained with the fertilising effect of cyanamide (Incorporation of a part of the added nitrogen in the soil micro-organisms seems to be the most likely explanation for this observation). It is not considered as an adverse effect.

Thus, as in the key study, it can be concluded that the use of the test substance, Cyanamid L500 is safe for soil non-target microorganisms.