Department of Soil Science, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, 263145, Uttarakhand.
*Corresponding author (Email: roomsingh.7@gmail.com)
1Present address: Department of Chemistry, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, 263145, Uttarakhand.
The effect of continuous cropping and fertilization on Zn fractions in soil and their relation with Zn uptake in rice-wheat system was studied in an Aquic Hapludoll of the G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during 2004–2005. Application of 100% recommended dose of NPK + Zn increased the ammonium acetate-extractable, HCl-extractable, residual and total Zn in the soil. Combined use of 100% NPK + FYM resulted in highest content of copper acetate-extractable as well as pyrophosphate-extractable Zn while the highest content of CBD-extractable Zn was found in the unfertilized fallow soil. All soil Zn fractions except CBD-extractable Zn, were significantly correlated among themselves indicating existence of a dynamic equilibrium with each other. Zinc uptake by rice-wheat was improved with conjoint use of 100% NPK and FYM. The most important chemical fraction of soil Zn with respect to the crop uptake was the HCI-extractable Zn.
Soil Zn fractions, Zn uptake, long-term fertilizer use
