Zinc Fertilizer Solubility and Its Effects on Zinc Bioailability Over Time

Abstract

ABSTRACT Studies have found that low water-soluble zinc (Zn) sources are not as effective in supplying Zn for plant use as highly water soluble ZnSO4·2H2O. However, there is a question as to the residual effects of Zn from low water-soluble fertilizers on subsequent crops. The objective of this greenhouse study was to determine the relationship between water solubility of Zn fertilizers and Zn availability over four cropping periods. Three Zn fertilizers with 99.7, 56.0, and 6.0% water solubility were evaluated at rates equivalent to 0, 5, 10, 15, and 20 kg Zn ha− 1. Four consecutive corn (Zea mays, L.) crops were grown in pots to the V-10 growth stage to determine Zn residual effects. Zinc fertilizer was only applied to the first crop, requiring subsequent corn crops to use residual Zn for nutrient needs. Results show that Zn sources with medium and low water solubility did not become more available over time, nor did they supply enough Zn to meet the crop's needs. The highly water-soluble source was effective in supplying Zn for two crops, after which plants showed Zn deficiencies. Zinc fertilizers of low solubility do not increase plant-available Zn over time. These results complement our previous research, and support the conclusion that Zn fertilizers of low water solubility are ineffective Zn sources for corn.