CORN RESPONSE TO 2 FERTILIZATION RATES UNDER SW SPAIN CONDITIONS - EFFECT ON THE FE, MN, ZN, CU AND B LEVELS OF THE PLANT

Iron, Mn, Zn, Cu and B contents of corn cv. PRISMA were studied in rel ation to two fertilizer treatments: the high rate used in irrigated fi elds in sw Spain (1000 kg/ha of 15-15-15 complex fertilizer and two ap plications of 400 kg/ha of urea, 46%N) and the same rate reduced to on e third. In general, the concentration of these micronutrients were al ways within the limits of the corresponding sufficiency ranges propose d in the literature for different stages of the crop. According to DRI S indices, Cu and especially Mn were clearly sufficient for PRISMA cor n throughout the period of cultivation, Zn being essentially balanced. Iron and B showed contrasting pattern, B being comparatively low init ially and essentially adequate at flowering and maturity, and Fe being quite sufficient initially and comparatively low at flowering and mat urity.