Biofortification through zinc fertilization: a field study of oat grown in an Andisol

Zinc (Zn) deficiency constitutes a health challenge particularly in South and Southeast Asia and Sub-Saharan Africa. Application of Zn fertilizers to crops, such as oat, offers a rapid solution to the problem. The purpose of this study was to evaluate the feasibility of oat biofortification through Zn fertilization, without causing Zn phytotoxicity to the crop. A field experiment was performed in Valdivia, southern Chile, in which oat (Avena sativa L.) grown in a Duric Hapludand soil was fertilized with zinc sulfate (ZnSO₄·7 H₂ O) with the following application rates: 0, 14, 43, and 85 kg Zn ha^-1, equivalent to 0, 8, 24, and 47 mg Zn kg^-1 soil. Diethylenetriaminepentaacetic acid (DTPA) solution was used to extract and measure the availability of Zn. The application of Zn at increased DTPA-Zn concentration considerably from 1.3 to 29 mg kg^-1 soil and Zn concentration in oat grains from 22 to 45 mg kg^-1. The application of Zn had no significant effect on grain yield. This study has practical agronomical implications by demonstrating that DTPA-Zn content of about 20 mg kg^-1 is optimal for increasing Zn content in oat grains grown in Andisols. This study demonstrates the technical feasibility of biofortifying crops with Zn grown in Andisols.