Effect of Sewage Sludge and Fertilizers Application on Accumulation of Heavy Metals and Yield of Rice (Oryza sativa L.) in an Inceptisol of Varanasi

A greenhouse study was conducted during July to October 2009 to find out the effect of conjoint application of sewage sludge and fertilizers on yield and heavy metals accumulation in rice. Five doses of sewage sludge as 0, 10, 20, 30 and 40 t ha⁻¹ were applied along with five levels of recommended dose of fertilizer (RDF as 0, 25, 50, 75 and 100%). Results of this study showed a significant increase in test weight and grain and straw yield. However, the values for harvest index were non-significant for different doses of sewage sludge. About 33 and 46% increase in grain yield was observed over control in the treatments where 100% RDF without sludge and 40 t ha⁻¹ sewage sludge without RDF was applied, respectively. Highest grain yield was recorded in the treatment where 40 t ha⁻¹ sewage sludge was applied along with 100% RDF. Application of sewage sludge along with fertilizers also increased Ni, Cr, Cd and Pb content in rice straw and grain. It was about 7, 5, 5 and 10 times increase in Cd, Cr, Ni and Pb content, respectively in rice grain and about 7, 3, 7 and 2 times increase in rice straw over their control.