Molybdenum in Nitrogen Metabolism of Legumes and Non-Legumes

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Abstract
A study was made of the growth and N metabolism of plants in relation to Mo supply. 4 soils low in available Mo were used in pot cultures for this work. Subterranean clover responded to Mo on each of the soils. Flax responded to Mo on only one of the soils in the presence of a heavy dressing of Mn sulfate, which reduced the uptake of Mo and induced Mo deficiency. Oats did not respond to Mo on any of the soils, even where Mn sulfate was added. High nitrate accumulation occurred in the flax provided with nitric acid but without Mo. Mo markedly increased both the yield and % N of clover where no combined N was provided, but had little or no effect where N was supplied as nitric acid or ammonium sulfate. The evidence with clover shows that Mo is directly concerned in symbiotic N fixation, and that the Mo requirement for opt. symbiotic N fixation is appreciably greater than the requirement for opt. utilization of nitrate N.