Effect of Sewage Sludge and Inorganic Fertilizers on Productivity and Micronutrients Accumulation by Palak (Beta vulgaris) and their Availability in a Typic Haplustept

This study evaluated the effect of sewage sludge obtained from three locations in Delhi namely, Okhla, Keshopur and Pappankallan on crop productivity and accumulation of micronutrients and heavy metals in plant and soil. Palak (Beta vulgaris) was grown as a test crop for the present study because of its capability to accumulate large quantities of heavy metals and also that sewage sludge is mainly used as amendment or source of nutrients for growing vegetables, especially in the peri-urban areas. Data revealed that biomass yield of Palak was significantly increased by application of sewage sludge, but the integrated management of sewage sludge and inorganic fertilizers performed better over only sludge amendment. Similarly, the micronutrients and heavy metal accumulation by Palak were greater in the treatments receiving conjoint use of sewage sludge and inorganic fertilizers compared to sludge application alone. But the accumulation of micronutrients and heavy metal was within the permissible limits. Soil amended with sewage sludge alone resulted in significant build-up in DTPA-extractable micronutrient and heavy metal over control. It was observed that conjoint use of sewage sludge and 50% NPK fertilizers resulted in further build-up of DTPA-extractable micronutrients and heavy metals over treatments receiving sewage sludge alone. Pearson's correlation matrix showed significant and positive relationships between biomass yield, accumulation of micronutrients and heavy metal by crop with DTPA-extractable micronutrients and heavy metal in soil. This study clearly shows the increased accumulation of micronutrients in foliage of Palak due to sludge amendment from all the three sources. Thus, it can be concluded that use of sewage sludge can be followed as a good supplement of nutrients for crop production, but care should be taken for the presence of heavy metals and pollutants.