Nitrogen and Legumes

An early depiction of root nodules of Vida faba by Malpighi (1679). 

Hellriegel and Wilfarth advanced three hypotheses that the erratic responses in legumes were caused by an unknown uncontrolled property residing in the soil that this activity should be transferable and, if it is of microbial origin, that it should 

Additional experiments during 1887 confirmed the original conclusions, and in 1888 Hellriegel and Wilfarth published a detailed account of their research whose basic conclusions remain unchanged more than a century later  

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