Wednesday, July 18, 2012



Uranium is universally present in the phosphatic fertilizers in the range of 20-300 mg/kg. This was stated by Dr. U.S.Sadana, Head, Department of Soil Science of Punjab Agricultural University. He added that analysis of fertilizer materials from Bhabha Atomic Research Centre, Mumbai showed that diammonium phosphate (DAP) and single super phosphate (SSP) available in Punjab contained 92 and 3 mg uranium per kg fertilizer. The uranium content in soils of long-term fertilizer experimental plots at PAU, where phosphatic fertilizers have been applied continuously for the last thirty years, is 5.2 mg/kg soil, which is within the normal range of 0.3-11.7 mg/kg soil, said he. In another depth-wise analysis of soil samples (carried out by Karlsruhe Institute of Technology, Germany) from Shaheed Bhagat Singh Nagar (Nawanshahar) district, where phosphatic fertilizers has been in use for last 20 years, uranium content ranged from 2.5 to 4.5 mg/kg soil. Dr. Sadana shared that from 38 years long-term phosphorus experiment in Ireland, it was concluded that the use of P fertilizer at normal rates used in agriculture is not a major threat to uranium content in the soil.

Discussing about the Punjab scenario, Dr. Raj Kumar, Senior Mineralogist, PAU said that uranium leaching may not be feasible in Punjab soils as solubility of calcium carbonate decreases with increase in temperature, high pH (7.5-9.5) and high bicarbonate concentration found in Malwa region of Punjab. Further, uranium-phosphate complexes form in the pH range of 4-6 under highly oxidized conditions, he added. As such, phosphatic fertilizers may not be contributing to the uranium content of underground water as majority of Punjab soils are alkaline in nature (pH 7.5-9.5). These facts imply that the use of phosphatic fertilizers has little effect on uranium status in groundwaters. Elaborating this further, he quoted Dr R. K. Sinha, Secretary, Department of Atomic Energy, who said, "In Punjab the low amount of phosphatic fertilizers mixed in soil did not justify the high level of uranium traces found in groundwater in five districts of the state." High uranium in groundwaters of south-west Punjab is more likely to be geo-genic in nature.

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