Long-term effect of sewage sludge and farmyard manure on grain yields and availability of zinc and iron under pearlmillet (Pennisetum glaucum)-Indian mustard (Bassica juncea) cropping sequence

Abstract

A study was conducted during 2005-07 to study the effect of sewage sludge with or without farmyard manure on yield of pearlmillet [Pennisetum glaucum (L.) R. Br. emend] and Indian mustard [Bassica juncea (L.) Czernj & Cosson] and micronutrient availability using the field that received the farmyard manure and sewage sludge treatments for preceding 5 years (2000-05). The treatments tried were sewage sludge @ 2.5, 5.0, 10 and 20 tonnes/ha, farmyard manure @ 5.0 and 10 tonnes/ha and farmyard manure+sewage sludge @ 10+2.5, 10+5.0 and 10+10 tonnes/ha in pearlmillet (kharif) in randomized block design with 3 replications. The residual effect was investigated on succeeding mustard crop. Both farmyard manure and sewage sludge were found beneficial in increasing grain yield and oil content of pearlmillet and it had a similar (residual) effect on succeeding mustard. Application of 10 tonnes farmyard manure + 10 tonnes sewage sludge/ha gave maximum yields of pearlmillet rain (1.16 tonnes/ha) and mustard seed (1.73 tonnes/ha). Use of sewage sludge increased the Zn and Fe contents in surface soil as well as in plant. The overall effect of farmyard manure + sewage sludge increased Zn and Fe uptake in both the crops, and organic carbon in soil. The DTPA-extractable Zn and Fe were higher in sewage sludge than in farmyard manure + sewage sludge or farmyard manure-treated soil.