This study was carried out to determine the effect of applying the six micronutrients compared with applying five (with the exclusion of one element) on growth and yield of maize. The soil was an alluvial clay with a pH value of 7.8 and containing available (DTPA • extractable) Fe, Mn, Zn, Cu and Mo were 9.8, 5.2, 2.66, 2.16 and 0.11 mg / Kg (ppm), respectively. Available (hot-water extractable) B was 0.4 mg /kg soil. The experiment included 8 treatments as follows = control (water sprayed), all trace elements and 6 treatment each missing one element all in mineral forms.
Results showed that spraying with the trace elements mixture except Cu led to a significant increase in ear leaf area, plant height, ear length, ear weight, grain weight / ear, weight of 100 kernels, weight of grains / plant in both seasons, ear diameter, number of kernels / row and shelling percentage in 1989 season, number of ears / plant in 1989 season and a significant decrease in days to 50% tasseling in both seasons. The exclusion of any of Cu, B or Mo from trace elements mixtures significantly increased grain yield by 24, 21 and 15% in 1987 season and by 23, 18 and 7% in 1989 season, respectively over the control treatment (water). Excluding Zn in particular led to a significant decrease in grain yield in the first season, showing a definite need for its application. Excluding either Fe or Mn led to a slight decrease indicating rather an adequate Fe and Mn content in the soil. A definite need of Zn application is pertinent. Application of Fe and Mn may also be recommended. Applying spray solutions of 0.4% ZnS04 + 0.4% MnS04 + 0.6% FeSo4 / fad. may be recommended for higher grain yield.
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