EFFICIENCY OF ZINC ETHYLENEDIAMINETETRAACETATE AND ZINC LIGNOSULFONATE SOLUBLE AND COATED FERTILIZERS FOR MAIZE CALCAREOUS SOIL

To test the effectiveness of coated and uncoated Zn fertilizers prepar ed with commercial zinc ethylenediaminetetraacetate (Zn-EDTA) and zinc lignosulfonate (Zn-LS), maize (Zea mays L.) was greenhouse cultivated in calcareous soils dosed with 5, 10, and 15 mg . kg(-1) Zn. Crop yie ld increased from 25 g per pot in control to 42 and 39 g per pot when 15 mg . kg(-1) Zn was added by applying Zn-EDTA-3 and Zn-LS-0 fertiliz ers, respectively. Although big amounts of Zn were taken by plants, co ncentrations in soil increased from 43 to 55 and 57 mg . kg(-1) when 1 5 mg . kg(-1) Zn as Zn-EDTA-3 and Zn-LS-3 was applied. Rosin coating i mproved the performance of Zn-EDTA fertilizers but scarcely did in fer tilizers with Zn-LS. A large part of Zn applied remained in the soil i n forms easily available to plants (water soluble plus exchangeable, o rganic complexed, and DTPA-extractable Zn), more so when the source of Zn was zinc lignosulfonate. Positive, significant correlations were o btained between the variables, yield, Zn concentration, and Zn uptake by the plant with respect to the available Zn and the first two sequen tially extracted fractions (water soluble plus exchangeable and organi cally complexed). The Zn uptake by maize could be fairly accurately pr edicted from the sequential fractioning in the soil after harvesting u sing an equation obtained through multiple regression analysis.