Molybdenum (Mo) is one of eight micronutrient elements required for the growth of plants. Research conducted in California nearly 40 years ago established its need for plant growth. Mo deficiencies have been reported throughout the world, especially on acid soils in the United States, Australia, and New Zealand. Generally, the Mo requirement of leguminous crops is greater than for non~legumes, but many non-leguminous field and vegetable crops have responded to additions of fertilizer Mo under severe deficiency conditions. Of all the nutrient elements required by plants for growth, Mo is needed in smallest amounts.
Sims, J. L., "Molybdenum Nutrition of Crops in Kentucky" (1981). Soil Science News and Views. 107.