Influence of zinc fertilization levels and frequencies on crop productivity, zinc uptake and buildup of soil zinc in maize–wheat system

Abstract

The zinc (Zn) requirement under intensive cropping system is higher due to continuous mining and the zinc fertilizers applied to the soil being adsorbed on soil colloids. Hence, detailed information of Zn is essential to understand the bioavailability processes. The present study was undertaken on an ongoing experiment initiated in 2012 at research farm of Department of Soil Science, Ludhiana with Zn levels i.e., 2.5, 5.0, 7.5 and 10.0 kg Zn ha−1 and three frequencies (once in six-year, alternate year, and every year) along with a control treatment. The maize and wheat yield were highest with the application of 10 kg Zn ha−1 every year which was at par with 7.5 kg Zn ha−1 every year and alternate year. The Zn uptake in maize and wheat was highest with 10 kg Zn ha−1 every year, which was statistically at par with 7.5 kg Zn ha−1 every year and 10 kg Zn ha−1 alternate years. The values of different fractions of zinc were higher with the application of 10 kg Zn ha−1 every year which was at par with 7.5 kg Zn ha−1 of every year and 10 kg Zn ha−1of alternate year. The different fractions of Zn i.e., residual zinc, crystalline FeO bound zinc, amorphous FeO bound zinc, organically bound zinc, manganese oxide bound zinc, carbonate bound zinc, specifically adsorbed zinc and water soluble + exchangeable zinc contribute 56.7, 16.0, 7.5, 5.1, 5.0, 4.8, 2.3, 2.2% to total Zn in soil. In overall it is concluded that the application of 10.0 kg Zn ha−1 in alternate year was found better for obtaining high crop yield and Zn uptake and for maintaining optimum available Zn in maize–wheat cropping system.