02309naa a2200181 a 450000100080000000500110000800800410001910000160006024500590007626000090013530000120014449000370015650001800019352014630037370000260183670000190186277302460188114668332007-07-27       2004    bl uuuu     u00u1 u    #d1 aKLEPKER, D.  aCritical levels of copper for soybean in cerrado soil.  c2004  ap. 257.  a(Embrapa Soja. Documentos, 228).  aEditado por Flávio Moscardi, Clara Beatriz Hoffmann-Campo, Odilon Ferreira Saraiva, Paulo Roberto Galerani, Francisco Carlos Krzyzanowski, Mercedes Concordia Carrão-Panizzi.  aIn micronutrient (Zn, Mn, Cu and B) fertilization trials performed since 1997 at two sites in the Balsas, MA, region, copper was the only micronutrient shown to constantly increase soybean yields. Recommended doses and critical levels of Cu in the soil have been assessed using the Mehlich-1 extracting solution, in a Red-yellow Latosol (LVAd). Although both sites has the same soil types one is a sandy clay loam (27% of clay) and the other has clay texture (55% of clay). In the sandy clay loam critical Cu levels were determined in the growing seasons of 2000/01 and 2001/02 while in the clay soil they were determined only in the 2001/02. The Cu doses that gave the Maximum Economic Yield (MEY) were approximately 1 kg/ha of Cu in the sandy clay loam and 6.5 kg/ha in the clay soil. The critical levels for the Mehlich-1 solution in the sandy clay loam were 0.39 mg/dm3 and 0.59 mg/dm3 of Cu in the growing seasons of 2000/01 and 2001/02, respectively. In the clay soil, the critical level was 0.78 mg/dm3 of Cu. The higher critical level for Cu given in the clay soil, may be related to its higher organic matter (OM) content (57.5 g/kg) compared to the sandy clay loam soil (29.3 g/kg OM), as well as to its higher MEY doses. The fact that the critical levels of Cu and the critical range recommended (0.5 and 0.80 mg/dm3) vary with soil texture means that texture dependent recommendations should be developed to maximize efficiency of fertilizer use.1 aOLIVEIRA JUNIOR, A de1 aBORKERT, C. M.  tIn: WORLD SOYBEAN RESEARCH CONFERENCE, 7.; INTERNATIONAL SOYBEAN PROCESSING AND UTILIZATION CONFERENCE, 4.; CONGRESSO BRASILEIRO DE SOJA, 3., 2004, Foz do Iguassu. Abstracts of contributed papers and posters. Londrina: Embrapa Soybean, 2004.