Soil degradation due to heavy metal accumulation under long term fertilization of paddy (Oryza sativa L.)
2014
Parameswari, E. | Davamani, V. | Arulmani, S. | Rathinasami, A.
Long term fertility experiment (LTFE) under double rice cropping system was investigated in Tamil Nadu Rice Research Institute, Aduthurai, India with two varieties (ADT 43 and ADT 45) in two seasons (Kharif and Rabi) under six fertilizer treatments to study the heavy metal accumulation in soil and its impact on paddy. There was a significant variation in physico-chemical properties of soil due to different fertilizer treatments. The surface soil (0-15cm soil depth) in all the treatments showed relatively higher heavy metal accumulation than subsurface. In thelong run, there was a build up in the total heavy metal content in soil and it was found to be relatively high in phosphatic fertilizer applied treatments than others. Total Cd and Pb was found high, but the availability was below detectable limit indicated that Cd and Pb were found in unavailable forms, while Cu and Zn were slightly in mobile forms which had been translocated into grain and straw of paddy. The DTPA (Diphenyl Triamine Penta Aceticacid) extractable Cd and Pb in the soil was low, but there was heavy increase in Cu and Zn comparing with initial period. The rate of increase in Cd and Pb content was lower in N alone and control plots. This might be due to the long term application of phosphotic and zinc sulphate fertilizers. Cd and Pb were evenly distributed at low concentrations in grain and straw under various treatments. In case of Cu and Zn, it was relatively higher in grains and paddy strawamong various fertilizer treatments. There was no significant difference among the varietal (seasons) treatments for the accumulation of heavy metals in grain and straw.
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