Nitrogen is a limiting plant nutrient because the bulk of the available nitrogen in the atmosphere is not usable by plants.
Plants are not able to make use of the nitrogen in the atmosphere directly. Atmospheric nitrogen needs to be converted into usable forms before it can be accessed by plants.
The conversion of atmospheric nitrogen to usable form by plants is known as nitrogen fixation and this is achievable by the activities of certain bacteria.
True ribs are ribs that are connected both at the back of the spine and at the sternum in front. false or floating ribs are not connected at the front which gives them less support and thus more easy to fracture.
