26 September 2014
Plants need nitrogen and carbon to grow. Photosynthesis allows them to take in the latter directly from the air, but they have to procure nitrogen through their roots in the form of organic molecules like ammonia or urea. Even though nitrogen gas makes up approximately 80 percent of Earth’s atmosphere, the plant can only access it in a bound – or ‘fixed’ – form. Farmers thus use fertilizers to provide their crops with nitrogen. The only living beings that can convert nitrogen from the air into usable molecules are microorganisms – for example nodule bacteria.
http://feeds.sciencedaily.com/~r/sciencedaily/~3/PH7wo2Obwao/140926085828.htm
