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Environmental fate & pathways

Biodegradation in soil

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Description of key information

Substance is readily biodegradable (according to OECD criteria), therefore no further biodegradation testing required under REACh

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Additional information

Substance is readily biodegradable (according to OECD criteria), therefore no further biodegradation testing required under REACh. The biodegradbility of IBDU in soil, however, was studied in several tests (e.g. Hughes 1976, Markova 1978).

Through its use as slow-release fertilizer, IBDU granules are directly applied on soil. With soil moisture, IBDU may be hydrolized to urea and isobutyraldehyde, dependent on pH, granular size and temperature (Hamamoto, 1966). Both substances are at least inherently biodegradable. Urea is decomposed by urease into NH3 and CO2 (ammonification) and NH3 then protonated into the ammonium ion. The latter volatilizes or is oxidized via nitrite into nitrate (nitrification). Low pH (pH < 6), high temperatures, high soil moisture and small granular size increase solubilisation of IBDU and, hence, mineralization (Hamamoto, 1966; Hughes, 1976; Markova, 1978). Within 24 weeks, the total amount of mineralized nitrogen in 4 different soil types with pH values of 4.8 to 8.3 was between 88 and 99 % of the introduced IBDU (Markova, 1978).