The Tri-State Fertilizer Recommendations (Bulletin 974, Ohio State/Purdue/Michigan State, corn/soybean/wheat/alfalfa) devotes a dedicated micronutrients section to corn and soybean. Deficiencies of boron, copper, manganese, molybdenum, and zinc can occur regionally; chlorine, molybdenum, and iron deficiencies are rare. Deficiency-prone conditions (Table 30): Cu on acid peats/mucks (pH<5.3) affecting corn/wheat/oats; Mn on peats/mucks (pH>5.8) and high-pH lakebed soils affecting soybean/corn/wheat/sugar beets; Mo on acid prairie soils affecting soybean; Zn on peats, mucks, and mineral soils with pH>6.5 affecting corn and soybean. Diagnosis relies on combining soil tests (0.1N HCl for Mn/Zn, 1.0N HCl for Cu, though Mehlich-3 is more commonly used regionally though not fully calibrated) with plant tissue analysis, since soil micronutrient tests are less reliable than for macronutrients. A synthesis of 194 Ohio trials (33 corn, 144 soybean, 17 alfalfa) found yield responses to micronutrient fertilization were rare — only Mn applied to soybean showed a response, in 9 of 144 trials. Reported adequate tissue ranges (ppm) include corn ear leaf at silking: B 10-44, Cu 6-19, Fe 87-448, Mn 16-86, Zn 14-45; soybean upper trifoliate at flowering: B 45-100, Cu 6-18, Fe 83-384, Mn 22-124, Zn 18-76. Recommended rates (Table 33): Mn = (6.2×soil pH) − (0.35×0.1N HCl-extractable Mn ppm) − 36 lb/acre (mineral soils); Zn = (5.0×soil pH) − (0.4×0.1N HCl-extractable Zn ppm) − 32 lb/acre; Cu = 6.3 − (0.3×1.0N HCl-extractable Cu ppm) lb/acre (organic soils). Broadcast Zn of 5-10 lb/acre can correct deficiency; broadcast Mn is discouraged due to soil fixation, so foliar Mn is preferred. Boron is not recommended for corn/soybean (only for alfalfa/clover at 1-2 lb/acre). Molybdenum for soybean: ½ oz sodium molybdate/bushel seed treatment or 2 oz/acre foliar spray on acid soils; high Mo can be toxic to livestock.