Rice, maize and sorghum may be able to fix nitrogen from the air

PLANTS NEED nitrogen to make proteins and DNA. But though this element is abundant in the air, they have failed to evolve the biochemical apparatus needed to break up nitrogen molecules and combine the resulting atoms with other elements (a process called “fixing”) in order to feed it into their biochemical pathways. Some bacteria have, however, managed this trick. And some plants, notably legumes, have worked out how to play host to these nitrogen-fixing bacteria by encouraging them to invade the cells of their roots, and by growing special root nodules to encourage such cohabitation.