A field experiment was carried out on a clay-sand-loamy Red-Yellow Latosol (Typic Acrustox) in Planaltina, Federal District, Brazil, during the cropping seasons of 1995/96, 1996/97 and 1997/98, to compare the effect of three methods of copper application (soil, foliar spray and seed treatment) on soybean (cv. Doko RC) grain yield and to determine the soil and leaf critical levels of that nutrient. There were no significant differences among the treatments in the first crop, probably due to a dry spell […]