Carbon dioxide enrichment effects on concentration, partitioning and uptake of metallic micronutrient elements in soybean under varied nitrogen application rates.

Information on the fate of micronutrients in plant tissue and total uptake from soil upon exposure to elevated carbon dioxide (CO2) is meager. Hence, this field study was conducted in open top field chambers to investigate the effects of elevated CO2 and applied nitrogen (N) on partitioning and uptake of zinc (Zn), copper (Cu), iron (Fe), and manganese (Mn) in soybean crop under two CO2 and four N levels during 2016 and 2018 crop seasons. The two CO2 concentrations were ambient and elevated (∼550 µmol mol−1). Nitrogen treatments included application at 0, 50, 100, and 150% of the recommended dose. Significant effects of CO2 and N were observed on grain yield, biomass and uptake of the four micronutrients. Seed Fe concentration was significantly increased by 12% under CO2 enrichment. Tukey's post-hoc test revealed significantly higher grain yield, biomass and uptake of micronutrients in seed and straw under CO2 elevation and at higher N application. Uptake of Fe, Zn, Cu, and Mn increased by 53, 42, 36, and 41%, respectively, in seed and by 25, 26, 31, and 18% in straw under elevated CO2. Total uptake of Fe, Zn, Cu, and Mn increased by 39, 38, 34, and 29%, respectively. Nitrogen at 100% level enhanced uptake of Fe, Zn, Cu, and Mn by 25, 20, 32, and 28%. The study bears implications in micronutrient management for sustaining soil health under changing climate. [ABSTRACT FROM AUTHOR]