Fertilizers and lime can carry several micronutrients as residual impurities, which can become a source of these elements for crops. This study quantified the concentrations of Zn, Cu, Fe, Mn, and Ni in fertilizers and lime sold in northeastern Brazil. The effect of these inputs on the indirect micronutrient supply to crops was evaluated. Extracts were obtained from 24 fertilizer and 26 lime samples, using the method 3051A (USEPA) and atomic absorption spectrophotometry for elemental analysis. A fertilizer sample (SRM 695 - National Institute of Standards and Technology - NIST) and spikes were added to monitor the analysis quality. In general, micronutrient concentrations were highest in phosphate fertilizers. Fertilizers and lime represent an important secondary source of micronutrients for the soil and should be considered in the management of soil fertility. However, the real availability of micronutrients from these materials must be assessed with plants in field experiments, since aspects such as solubility, reactions with soil, and leaching losses can affect the actually available amount for plant uptake.
trace elements; phosphate fertilizers; lime; heavy metals
