International units.

ــلا Micronutrients are ..etc… Rationale A pot 3-factor trial Seed and ..etc.. There is need for …etc. ABSTRACT Micronutrients are becoming increasingly applied in combinations to soybeans in view of high-yielding cultivars, hence assessment of their interactions is vital . A pot 3-factor trial on Zn-Mn-Co interaction was done using soybean ( Glycine max L.) on a TypicHaploargid light clay soil. Treatments being Zn 0, Zn 1 ,Zn 2 ; Mn 0 , Mn 1 , Mn 2 at 0, 5 , and 10 mg kg - 1 respectively for each ; Co 0 ,Co 1 and Co 2 at 0 , 2.5 , and 5.0 mg kg -1 respectively Seed yield, and nutrient uptake per pot of non-fertilized were:10.8 g 237 ug Zn, 267 ug Mn, and 2.13 ug Co. Giving each singly or combined with other(s) raised yield by up to 36%. Added alone, Zn gave 28% ,but no or little increase in presence of Mn or Co. Mn with no Zn gave 34 % increase but in Zn presence, had no effect or16% decrease. Co when alone increased yield slightly. Zn uptake rose by 8 % (Zn 0 Mn 2 Co 0 ) to 82% (Zn 2 Mn 0 Co 0 ). Zn increased its uptake by 68 to 82% .Zn uptake rose by up to 20% by Mn alone in absence of others. Co alone increased Zn uptake by up to15%, but given with other(s) it caused a decrease. Mn,singly increased Mn uptake by 30 to 45 % , and lower when combined with others . Zn increased Mn uptake by 5 to 10% on average, and to 13% when singly. There is a need for balanced Zn-Mn-Co combination to get most benefits.