03208naa a2200181 a 450000100080000000500110000800800410001910000190006024500770007926000090015630000160016549000370018150001800021852023390039870000160273770000270275377302460278014667962007-07-27       2004    bl uuuu     u00u1 u    #d1 aBORKERT, C. M.  aSoybean response and residual effect of micronutrients in Cerrado soils.  c2004  ap. 185-186.  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.  aWith the increase of soybean yields in the last years, there is a greater concern for furnishing micronutrients for this crop. The quantity of micronutrients exported by the seeds increased because of the high yields of the new soybean varieties. Besides, native cerrado soils, have in general, low availability of micronutrients, mainly, zinc, manganese and copper, which may lead to possible deficiencies of these nutrients in soybean. Thus, the objective of the present study was to evaluate the effect of the application of these micronutrients on soybean yield, under different soil acidity conditions.The research began in 1997, at two sites in the South of the State of Maranhão and included experiments for calibrating the recommendable doses and the critical levels of Zn, Mn, Cu and B. Each experiment was run in a factorial arrangement (6 X 6), including six doses of lime in order to obtain high levels of base saturation between 30 to 80 % and also six doses of each micronutrient. The experiments were run in a randomized block design with split plot and four replications. At both sites the soil was classified as a distrofic Red-yellow Latosol (LVAd), however, with different soil texture, sandy clay loam (27% of clay) and clay soil (55% of clay). In both soils, the initial soil content of Zn and Cu (Mehlich-1) and of B (Hot Water) were below the critical levels of these nutrients in the soil; 1.0 , 0.8 , and 0.5 mg/dm3, respectively, while the initial content of Mn was higher than the critical level of 5.0 mg/dm3. In general, there was no significant response to application of the micronutrients, Zn, Mn, and B in the five growing seasons 1997/98 to 2001/02 and even when the response was significant yield increases due the application of the micronutrients were small. However, a significant effect of Cu application was observed at both sites, indicating that this is the main limiting micronutrient in soils of this region. The increase of the level of base saturation had significant effect on soybean yields, with the highest increases in the clay soil. The small response to application of micronutrients in the present trials may be due to the addition of nutrients as contaminants in lime and in fertilizers, and by the capacity of the soybean roots to solubilize and to absorb these micronutrients.1 aKLEPKER, D.1 aOLIVEIRA JUNIOR, A. de  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.