Residual and cumulative effect of fertilizer zinc applied in wheat-cotton production system in an irrigated aridisol

Abstract

The objectives of present study were to determine the residual and cumulative effects of zinc (Zn) fertilizer on cotton (Gossypium hirsutum L.) and wheat (Triticum aestivum L.) in a silt loam Typic Haplocambid soil (< 0.05 mg/kg diethylenetriaminepentaacetic acid (DTPA)-Zn). The study comprised of two years field experiments where first cotton crop received zinc sulphate (ZnSO₄∙H₂O) at five rates (0, 5, 7.5, 10, 12.5 kg Zn/ha) in a randomized complete block design with four replications. After harvest, each plot was divided into two sub-plots. To study the residual effect, one sub-plot of all plots did not receive Zn fertilizer for the subsequent crops; however, the other sub-plot received all Zn rates for 2005–06 wheat, 2006 cotton, and 2006–07 wheat. Fresh applied, residual as well as cumulative Zn application significantly (P ≤ 0.05) increased crops production for both experimental years. Residual effect of 5.0 kg Zn/ha optimized the 2006 cotton yield; however, wheat productivity was optimized with residual effect of 7.5 kg Zn/ha in 2005–06 and of 10.0 kg Zn/ha in 2006–07. Optimum yield of both crops was attained with a lesser fresh-applied and residual Zn rate than cumulative Zn rate. Total Zn uptake by wheat (134.9–289.6 g/ha) was much greater than by cotton (92.3–192.5 g/ha). It is concluded that one application of 7.5 kg Zn/ha proved adequate for optimizing two cycles of the cotton-wheat production system. Two-year repeated use of 5.0–7.5 kg Zn/ha did not depress crop yields.