Effect of urea and ammonium nitrate on the uptake of iron through leaves

Greenhouse experiment was conducted to study the effect of urea and ammonium nitrate on the uptake of iron through the leaves of plants. Iron from different sources was applied to the foliages of the plants with and without the addition of urea and ammonium nitrate. The iron solution used in the foliar spray contained 400 ppm of iron from FeSO4 · 7H2O, Fe‐EDTA and Fe‐amino acid chelate (Fe‐AA). The nitrogen concentrations in the final solution were 500 and 1000 ppm with half of the nitrogen from urea and other half from ammoniun nitrate. The addition of urea and ammonium nitrate increased the effectiveness of FeS04 · 7H2O used in foliar application. Urea and ammonium nitrate had no effect on Fe‐amino acid chelate but decreased the effectiveness of Fe‐EDTA when the nitrogen concentration was increased to 1000 ppm. On the average, Fe‐amino acid chelate increases the dry matter yield but not FeSO4 · 7H2O and Fe‐EDTA. Nitrogen alone did not significantly affect the dry matter yield. Higher iron concentration in the leaves was obtained by the use of Fe‐amino acid chelate than FeSO4 · 7H2O and Fe‐EDTA. With the chelates, more iron was translocated to the roots than with FeSO4 · 7H2O. Foliar application of Fe‐amino acid chelate increased the manganese concentration in the plants. Addition of urea and ammonium nitrate to the iron solution also increased the uptake of manganese. The increase in manganese in the plants by the foliar application of iron may contribut to the increase in dry matter yield.