World Congress of Soil Science Logo 18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA
International Union of Soil Sciences

Monday, 10 July 2006 - Friday, 14 July 2006
164-12

This presentation is part of 164: 4.1PA Soils and Natural Hazards (Knowledge, Assessment and Mitigation) - Poster

Effect of Applied Phosphorus and Vermicompost on Removal of Heavy Metals by Leafy Vegetables in Polluted Soil.

Velugubantla Adinarayana and Sukruth T. Kumar. Acharya N.G. Ranga Agricultural Univ, Rajendranagar, Hyderabad, India

Investigations were carried out through pot experiment in a green house at Agricultural College campus of Acharya N.G. Ranga Agricultural University, Hyderabad, India during rabi 2002. An identified polluted soil was collected from Afzalgunj area occurring along Musi river bank of Hyderabad. The soil was from the site where three leafy vegetable crops (Amaranthus, Hibiscus and Palak) employed in the experiment are predominantly grown from time to time using polluted water of Musi river. This soil was found to be highly contaminated with heavy metals which are originated from industries and sludge of the urban waste. The experimental soils are sandy clay in texture with pH of 6.1 and EC of 0.14 dS/m. The soils were found to contain 37.58 Zn, 42.63 Cu, 83.20 Fe, 6.74 Mn, 35.68 Pb, 0.916 Ni, 1.013 Cr, 1.042 Co, 0.658 Cd Mg/kg soil as extracted by DTPA. The sum of DTPA extractable toxic metals (Pb + Ni + Cr + Co + Cd) was 39.30 Mg/kg soil. Available nitrogen, phosphate and potash were found to be 290, 18, 37.58 kg/ha respectively. Amaranthus produced highest fresh weight yields (65.76 g/pot) followed by Hibiscus (48.28 g/pot) and palak (25.04 g/pot). Lowest fresh weight yields were recorded in absolute control (37.36 g/pot) while highest fresh weight yields (56.46 g/pot) were recorded with the treatment where 200% recommended P and 2 t vermicompost per hectare were supplied. The dry matter yields followed exactly the similar trend of fresh weight yields in respect of crops as well as treatments. The behavior of each heavy metal viz., Pb, Cd, Ni, Cr and Co in the leafy vegetables was observed to be different with the application of phosphorus and vermicompost to the polluted soil. The contents of heavy metals were in order of Pb > Cr > Co > Ni > Cd in these leafy vegetables viz., palak, amaranthus and Hibiscus grown on pollutes soil. While heavy metal content in the crops increased with the addition of phosphorus from 0 to 20 kg/ha in respect of lead, chromium and cadmium, the contents of cobalt and nickel decreased with phosphorus application. Excess phosphorus application with or without vermicompost decreased the concentration of all the heavy metals in plants. Application of excess P (200%) depressed total toxic metal load by about 19.6 per cent over reference control. Increase in the micronutrient content was observed for Fe, Cu and Mn but not with Zn with excess phosphorus application. However, vermicompost addition resulted in increased content of zinc also. The crops deferred in contents of different cationic micronutrients. The total load of heavy metal contents (Pb + Cd + Ni + Cr + Co) in leafy vegetable crops, grown on polluted agricultural soil, was found to be reduced by 24.6% over the absolute control (where no fertilizer was applied) and by 28.9% over the reference control (100% RDF) due to application of 40 kg P 2O 5 and 2t vermicompost per hectare. The order of efficacy of different treatments along with recommended doses of N and K for depressive effects of toxic metals load in leafy vegetables was found to be as follows: [40 kg P 2O 5/ha (200% RD) + 2t vermicompost/ha] > [40 kg P 2O 5/ha (200% RD) + 1t vermicompost/ha] > [40 kg P 2O 5/ha (200% RD)] > [60 kg P 2O 5/ha (300% RD) + 2t vermicompost/ha] > [20 kg P 2O 5/ha (100% RD) + 1t vermicompost/ha] > [60 kg P 2O 5/ha (300% RD) + 1t vermicompost/ha] > [20 kg P 2O 5/ha (100% RD) + 2t vermicompost/ha] > [20 kg P 2O 5/ha (100%RD) + 1t vermicompost/ha]. The order of depressivity with in the toxic metal ions in the plants for all the treatments put together was as follows : Chromium (15.95%) > Lead (13.88%) > Cadmium (13.75%) = Cobalt (13.74%) > Nickel (11.60%). This shows that the application of different treatments to polluted soil can depress the toxic metals load in leafy vegetables within the range of about 11 to 16 per cent over reference control (100% RDF). Based on total toxic metal load concentration in leafy vegetables plants, the order of preference among these crops to be grown on polluted soil is as : Hibiscus (25.093 mg/kg) > Palak (34.073 mg/kg) > Amaranthus (35.70 mg/kg). Hibiscus crop also showed the lead content less than critical limit on supply of 40 kg P 2O 5/ha with or without vermicompost. The present investigations indicated that it is advisable to prefer growing of Hibiscus among leafy vegetables with the application of 40 kg P 2O 5 + 2t vermicompost along with 20 kg N + 20 kg K 2O per hectare on polluted soils of Afzalgunj area along the banks of Musi river in Hyderabad, India.

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