Fate and plant uptake of different zinc fertilizer sources upon their application to an alkaline calcareous soil

Authors: CHAHAL, SEVENDEEP - Kansas State University; HETTIARACHCHI, GANGA - Kansas State University; NELSON, NATHAN - Kansas State University; Guttieri, Mary

Submitted to: American Journal of Agricultural Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2023
Publication Date: 9/5/2023
Citation: Chahal, S.K., Hettiarachchi, G.M., Nelson, N., Guttieri, M.J. 2023. Fate and plant uptake of different zinc fertilizer sources upon their application to an alkaline calcareous soil. American Journal of Agricultural Science and Technology. 3:725-737. https://doi.org/10.1021/acsagscitech.2c00287.
DOI: https://doi.org/10.1021/acsagscitech.2c00287

Interpretive Summary: Calcareous soils, which have high concentrations of calcium carbonate, tend to form in hot, dry environments. Plants grown in calcareous soils often suffer from micronutrient deficiencies. The chemical form of zinc fertilizer can affect the availability of zinc to growing plants. This study evaluated the zinc availability of several different zinc fertilizer sources in calcareous soil. Our experiments measured zinc solubility and diffusion in the soil matrix. We also measured wheat plant zinc uptake. The efficiency of the Zn fertilizers depended on solubility, resultant pH, and tendency to diffuse and avoid sorption reactions. The superior agronomic effectiveness of ZnEDTA in calcareous soils resulted from its enhanced distribution, extractability, and solubility in soil. The concern with ZnEDTA is that it is highly mobile in soil and prone to leaching through the root zone. Zinc oxide and Zn mix (60% ZnO) treatments were relatively less soluble and acted as slow-release fertilizers in calcareous soil. Low solubility for ZnO and Zn mix kept Zn sufficiently soluble to provide adequate amounts of Zn to produce plant biomass and plant Zn uptake similar to ZnEDTA. The results of this study will assist agronomic scientists and crop fertility specialists who make fertilizer strategy recommendations for producers with calcareous soils.

Technical Abstract: To effectively manage soil for optimum crop production, it is crucial to understand how zinc (Zn) interacts and speciates in Zn-deficient calcareous soils. This study employed incubation-visualization and short-term (5 weeks) greenhouse studies to evaluate fate, transport, and extractability of Zn in soil and Zn plant uptake. Further X-ray absorption near-edge structure (XANES) spectroscopy was employed to identify the chemical species of Zn in Zn-coated urea-treated soils. The objectives were to compare the efficiency and investigate the reaction products and pathways of Zn-only sources and Zn-coated urea sources in a calcareous soil. Out of Zn-only treatments, plant biomass was significantly higher for ZnO (0.62 g) and Zn mix (60% ZnO plus ZnSO4 and Zn-EDTA) (0.71 g) than the no-Zn control (0.4 g), ZnSO4 (0.5 g), and ZnP (0.5 g). Meanwhile, Zn diffusion and extractability were greatest for ZnEDTA, and this was supported by soil solution Zn results, which indicated that the solution Zn concentration in ZnEDTA was on an average 13 times greater than all other Zn-only treatments and the control. Zinc-coated urea sources provided more soluble and plant-available Zn, likely due to the enhanced solubility facilitated by urea. Synchrotron-based XANES results were in agreement and confirmed various resulting reaction products for Zn-coated urea products. Our results showed that, in calcareous soils, high solubility might not be the only indicator to test Zn fertilizer use efficiency; less soluble sources behave as efficiently as highly soluble sources due to their ability to reduce sorption reactions limiting Zn availability.