Copper and Zinc Availability in Mineral Fertilizers

Abstract

The safety and efficiency of inputs are crucial to the success of agriculture. Despite the current legislation for fertilizers containing micronutrients to soil application to enable more efficient control of the quality of these materials through the mandatory 60% solubility in a second extractor, and of the amount with HCl, there are doubts whether this index is valid for different fertilizers sold in the country. The objective of this project is to provide technical support for the Brazil Ministry of Agriculture (MAPA) concerning the analysis of solid mineral fertilizers applied to the soil containing copper (Cu) and zinc (Zn).The amount contents of Cu and Zn in fertilizers will be determined by the official method of MAPA (HCl) and the USEPA method 3051A (nitric acid in a microwave oven). Furthermore, we analyze the safety of fertilizers, the presence of heavy metals (Cd, Cr, Ni and Pb). The available contents of Cu and Zn, for the second extractor will be determined by official methods of MAPA: neutral ammonium citrate (CNA) + water (1:1) for Cu and citric acid (AC) 2% for Zn, in addition to methods: water, hot water, DTPA, EDTA, H2SO4, HCl, buffer pH 6.0 and CH3COOH (acetic acid - AcOH).There are soluble fertilizers, oxides, ores and secondary materials used by the productive sector. A second experiment will be installed in a greenhouse, using as test corn (Zn) and wheat (Cu), two soil types (sandy and clay) and five sources of Cu fertilizers and seven sources Zn fertilizers.The results of the levels available in the fertilizer will be correlated with the absorption of Cu in wheat plants and Zn by corn plants. Furthermore, correlations are made between the amount and available Zn and Cu extracted by various methods. The aim is to elect (s) extractor (s) most promising to set the availability of Cu and Zn present in fertilizers and to determine the minimum index of solubility of 60% applies to the variety of micronutrient fertilizers sold in Brazil.