## 3 Results
In grain, for Co, Cr and Fe; in cob, for P and Mn; and Co, Cr and Pb in plant; means with different letters are significantly different according to the DMRT (\(\alpha\) = 0.05). Figure 4: Accumulated average extractions of N and K (**a**); P, Mg and S (**b**); Cr, Cu and Mn (**c**); Co and Pb (**d**); Fe and Zn (**e**); and Cd (**f**); from average extractions in different parts of maize plants, and for each treatment (MIN: mineral; SPC: sewage sludges, P criterion; SNC: sewage sludges, N criterion). In grain, for Cr, N and S; in cob, for Cd; and in straw, for P and Zn; means with different letters are significantly different according to the DMRT (\(\alpha\) = 0.05). In grain, the SNC showed the highest values in chrome concentration (1.5 mg Cr kg\({}^{-1}\), Figure 3d) and iron (33.6 mg Fe kg\({}^{-1}\), Figure 3c), but it only differed from MIN in cobalt concentrations (26.1 and 9.5 mg Co kg\({}^{-1}\) for SNC and MIN, respectively; Figure 3e). Phosphorus (Figure 3b) and manganese (Figure 3c) concentrations in cobs were lower in the MIN treatment than for the SNC and SPC. In cobs, P values ranged from 0.59 to 0.80 mg P kg\({}^{-1}\), while in Mn, they ranged from 6.4 to 7.2 mg Mn kg\({}^{-1}\). In the rest of the plant, Co (Figure 3e) and Cr (Figure 3d) concentrations were lower for the SPC than in the rest of treatments. Concentrations ranged from 79 to 100 ug Co kg\({}^{-1}\), while in Cr, they ranged from 0.32 to 0.51 mg Cr kg\({}^{-1}\). Also, for the rest of the plant, Pb concentrations (Figure 3e) were lower in the SCP (228.6 mg Pb kg\({}^{-1}\)) than in MIN (283.2 mg Pb kg\({}^{-1}\)) and SNC (288.5 mg Pb kg\({}^{-1}\)). For the rest of concentrations analyzed, without significant differences between fertilization treatments (Tables A3-A9; Figure 3), the average values (\(\pm\) standard deviation) for grain were 12.1 g N kg\({}^{-1}\) (\(\pm\)0.4), 4.2 g K kg\({}^{-1}\) (\(\pm\)0.1), 2.7 g P kg\({}^{-1}\) (\(\pm\)0.1), 1.3 g Mg kg\({}^{-1}\) (\(\pm\)0.04), 1.3 g S kg\({}^{-1}\) (\(\pm\)0.1), 5.2 mg Mn kg\({}^{-1}\) (\(\pm\)0.3), 22.8 mg Zn kg\({}^{-1}\) (\(\pm\)1.4), 3.1 mg Cu kg\({}^{-1}\) (\(\pm\)0.1), 12.2 ug Pb kg\({}^{-1}\) (\(\pm\)2.7) and 1.4 ug Cd kg\({}^{-1}\) (\(\pm\)0.2). For cobs, the average concentration values (\(\pm\)standard deviation) were 7.9 g N kg\({}^{-1}\) (\(\pm\)0.8), 11.0 g K kg\({}^{-1}\) (\(\pm\)0.7), 0.6 g Mg kg\({}^{-1}\) (\(\pm\)0.1), 0.7 g S kg\({}^{-1}\) (\(\pm\)0.05), 29.0 mg S kg\({}^{-1}\) (\(\pm\)2.0), 32.0 mg Zn kg\({}^{-1}\) (\(\pm\)7.5), 3.1 mg Cr kg\({}^{-1}\) (\(\pm\)0.2), 3.4 mg Cu kg\({}^{-1}\) (\(\pm\)0.1), 31.5 ug Co kg\({}^{-1}\) (\(\pm\)2.0), 24.3 ug Pb kg\({}^{-1}\) (\(\pm\)1.8) and 16.0 ug Cd kg\({}^{-1}\) (\(\pm\)8.9). For the rest of the plant, the average concentration values (\(\pm\)standard deviation) were 4.9 g N kg\({}^{-1}\) (\(\pm\)0.7), 15.4 g K kg\({}^{-1}\) (\(\pm\)0.3), 1.2 g P kg\({}^{-1}\) (\(\pm\)0.5), 1.6 g Mg kg\({}^{-1}\) (\(\pm\)0.2), 1.0 g S kg\({}^{-1}\) (\(\pm\)0.1), 222.4 mg Fe kg\({}^{-1}\) (\(\pm\)27.7), 39.2 mg Mn kg\({}^{-1}\) (\(\pm\)10.0), 17.5 mg Zn kg\({}^{-1}\) (\(\pm\)7.0), 4.1 mg Cu kg\({}^{-1}\) (\(\pm\)0.1) and 12.2 ug Cd kg\({}^{-1}\) (\(\pm\)2.7). Extractions diminished for the SPC treatment when compared with MIN in grain N (23 kg N ha\({}^{-1}\)) and cob Cd (6 mg Cd ha\({}^{-1}\)) (Figure 4a,f). The SNC treatment, when compared with MIN, reduced grain S (Figure 4b) and cob Cd (Figure 4f) extractions by 2 kg S ha\({}^{-1}\) and 5 mg Cd ha\({}^{-1}\). No differences were found in the fractionated maize extractions of the rest of elements (K, P, Mg, Cu, Mn, Fe, Zn, Co and Pb) (Figure 4).