Determination of Acute Toxicity of Urea to Eisenia Fetida by a Simple Paper Contact Method

Urea is the most commonly used nitrogen fertilizer worldwide. The overused urea in agricultural fields may affect the soil organisms especially, the earthworms which are known well for their role in soil fertility. Earthworms are typically inferred as soil indicators without which soil fertility cannot be measured directly. An acute toxicity test of urea to earthworm (Eisenia fetida) was performed using a simple paper contact method proposed by OECD (Organization for Economical Cooperation and Development) testing guideline no. 207. This is a simple screening test to identify the toxic potential of the chemical to earthworm. The lethal concentration was recorded as 28μg/cm 2 . Based on the resulting LC50 value, urea was categorized as “very toxic” to earthworm according to Roberts and Dorough (1984). The result of this study demonstrates that inorganic fertilizers can also be toxic to earthworms when contacted directly. Thus there arises an unavoidable need for monitoring the usage of fertilizer dosage on agricultural lands, particularly the urea.