Influence of sewage sludge application on soil properties, carrot growth and heavy metal uptake

Abstract

ABSTRACT A pot experiment with carrot (Daucus Carota L.) was conducted aiming to investigate some soil properties, growth and heavy metal uptake by carrot with the application of sewage sludge. The treatments used were as T1 Control (Soil only), T2 (Soil + NPK), T3 (Soil 50% and sewage sludge 50%), T4 (Soil 60% + sewage sludge 40%), T5 (Soil 70% + sewage sludge 30%) and T6 (100% Sewage sludge). The results showed that sewage sludge application significantly influenced soil pH, organic matter (OM), electrical conductivity (EC), exchangeable potassium (K) and available phosphorus (P). Heavy metals like lead (Pb), cadmium (Cd), nickel (Ni) and chromium (Cr) content in soil and plant were increased due to the application of sewage sludge. Heavy metal content in soils for different sludge treatments was lower and that in carrot samples was higher than the WHO/FAO permissible limit. The carrot was recognized by a translocation factor <1.0 for all of the heavy metals except Cd. Plant heavy metal concentrations were positively correlated with the soil organic matter content and negatively correlated with soil pH. The growth of carrot was influenced positively with sewage sludge application. Maximum fresh weight (66.3 g plant-1) was recorded in T5 treatment, and maximum dry weight (5.61 g plant-1) was in T3 treatment. The soil application of sludge improves soil fertility and enhances the better yield of carrot. Moreover, sewage sludge could be co-recycled to take simultaneously the best profit and minimize environmental pollution.