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Toxic effect of superphosphate on soil ecosystem using earthworm Drawida willsi as test specimen

Anindita Bhattacharya, Sanjat Kumar Sahu

P.G. Department of Environmental Sciences, Sambalpur University, Odisha, India

Department of Forestry & Environmental Sciences, Guru Ghasidas University, Bilaspur, Chhattisgarh, India

Key words: Fertilizer, Superphosphate, toxicity test, earthworm.


Fertilizer-Farm-Rice-FieldIn the name of “Green Revolution”, enormous use of agrochemical had resulted threat to soil ecosystem by killing the beneficial soil organisms including earthworm. Several studies were conducted on the toxic impact of some fertilizers on earthworm. On contrary, few studies were conducted on the effect of superphosphate on earthworm and no concrete conclusion could be found out. So the present experiment was undertaken to find out the effect of superphosphate on soil ecosystem using earthworm (Drawida willsi) as test animal. For this different concentration of superphosphate were mixed with water and added to the replicates of soil containing different age group of D.willsi. In control, only water was added to soil. Earthworm deaths were recorded with respect to different dose of Superphosphate and Finney’s probit method was followed to calculate 96h LC50 values. The experiment found that all the juvenile and immature worms thrived in soil containing up to 50 mg/kg while adult at 100 mg/kg of superphosphate. Worms were when exposed to concentration as high as 400 mg/kg of superphosphate, 100% of juveniles were killed. However at the same concentration 74% of immature and 53% of adults were killed. The 96 h LC50 values with their 95% confidence limits for juvenile, immature and adult worms were 222.8 (222.77-222.83), 262.4 (262.35-262.45) and 314.05 (313.98-314.12) mg/kg respectively. This indicates that the earthworms were affected by the use of Superphosphate. So it is suggested that Superphosphate should be used in their recommended doses to maintain the soil health.

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