Evaluation of irradiated sewage sludge as a source of micronutrients for a maize-green gram cropping sequence

Sewage sludges as manures are the important sources of nutrients to plants. Appropriate treatment of sewage sludge before soil application without reduction in its manurial value is being attempted throughout the world. A microplot field trial has been conducted to evaluate the plant uptake of micronutrients by maize (Zea mays L.cv. Ganga local) followed by green gram (Phaseolus aureus Roxb. cv. ML-5) grown on an inceptisol amended with normal (municipal) sewage sludge (NSS) and irradiated sewage sludge (ISS) at application rates of 1 to 4 t ha-1. Results indicate that both these sludges were at par with respect to dry matter yield of shoot and grain of both the crops. No significant differences were observed between NSS and ISS treatments in terms of Cu, Zn, Mn and Fe uptake by both crops. However, in general , shoot content of these elements was higher than the grain content of maize. Mn content in the shoot and grain of green gram followed the same pattern but Cu and Zn content in shoot and grain were on par. Marginal improvements in soil properties such as enhancement in water holding capacity, organic carbon content and cation exchange capacity, due to sludge application as compared to no sludge treatment, were observed. (author)