Question

state how nitrogen is utilised by plants for their growth

Answer 1

It depends on the type of plant. Some plants get the nitrogen they need from decomposition of other plants animals and animal faeces. Other plants such as legumes have small nodules on their roots which contain bacteria that can fix nitrogen from the atmosphere.  A small number of plant species catch and digest small animals usually insects. Nitrogen is also added to the soil by nitrogen fixing bacteria that live independently of root nodules and also via lightning strikes. 
Of course when we want a very high yield of plants from a limited area, crops for instance, we can fix the nitrogen out of the atmosphere ourselves by fractional distillation and then combine it with hydrogen to form ammonia. From that we can make all sorts of synthetic compounds that will boost plant growth.

Hope it help.

Answer 2

HEY MATE ❌❌Biologically: Nitrogen gas (N2) diffuses into the soil from theatmosphere, and species of bacteria convert this nitrogen to ammonium ions (NH4+), which can be used by plants. Legumes (such as clover and lupins) are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria.❌❌MATE HEY