Impact of Long-term Application of Green Manuring on Vertical Distribution of DTPA-extractable Zinc and Organic Carbon

A field experiment on zinc deficient Calciorthents has been in progress at Rajendra Agricultural University, Pusa research farm since kharif 2000 to study the effect of green manuring on zinc nutrition in rice-wheat cropping sequence. The green manuring treatments were compared with FYM and ZnSO₄ application. The organic carbon and DTPA-Zn content decreased vertically with increase in soil depth after completion of 4^th cropping cycle. Among green manures, dhaincha was more effective in enhancing organic carbon and DTPA-Zn content in soil. However, green gram along with 5 t FYM ha⁻¹ was most effective among all the treatments. The DTPA-Zn showed positive correlation with organic carbon content indicating that application of organics increases the organic matter content that provides chelating agents for complexation of native or added Zn.