Molybdenum is essential for all living processes. In agriculture, it is necessary for proper utilization of nitrogen. Plants absorb most of their nitrogen in the nitrate form (NO3) and must reduce it to the amino form (NH2) to be used in protein formation. Molybdenum is an essential part of the nitrate reductase enzyme which is involved in this reduction process. In plants with Molybdenum deficiency, nitrates continue to be taken up but are only accumulated, not utilized. Ammonium compounds (NH4+) are better utilized than nitrates but, if molybdenum is deficient, even ammonia-based fertilizers are not efficiently converted to the proper amino form.
Molybdenum is also essential to azotobacter, the nitrogen fixing bacteria in the root nodules of leguminous plants. For this reason, legumes have a higher molybdenum requirement than nonleguminous plants. Molybdenum deficient legumes commonly show nitrogen deficiency. It has been calculated that molybdenum is more efficient, pound for pound, in making usable energy available than uranium. To produce an atomic bomb having an energy release equivalent to 20,000 tons of TNT requires 360 pounds of uranium 235 - uranium238 mixture. The same amount of energy in the form of increased forage yield can be obtained by adding 1 oz. of molybdenum per acre to 3500 acres of a molybdenum deficient leguminous crop such as clover (218 lbs. of molybdenum).
Symptoms of molybdenum deficiency in plants is stunting and lack of vigor. This is similar to nitrogen deficiency due to the key role of molybdenum in nitrogen utilization by plants.
In animals no molybdenum deficiency symptoms have been found, but it does cause excess diarrhea. This can be corrected by spraying pastures with copper.
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