Impact of long term application of crop residues and residual zinc on vertical distribution of organic carbon and DTPA-Zn

Abstract

The long-term effect of crop residue incorporation and residual Zn in rice-wheat cropping sequence was studied in calciorthents of Rajendra Agricultural University, Pusa, Samastipur, Bihar, India during 2011-12. The crop residue treatments are compared with residual ZnSO4 application. Both organic carbon (OC) and DTPA-Zn contents decreased with increase in soil depth after completion of 18th cycle. Among crop residue and residual Zn treated plots, the ones with crop residues were found more effective in enhancing the OC and DTPA-Zn content in soil. The DTPA-Zn showed positive correlation with OC content indicating that application of crop residue increased organic matter that provides chelating agents for complication of native or added residual Zn.