Determine how nitrogen is useful in plant nutrients

The supply of nitrogen is related to carbohydrate utilisation. If nitrogen supply is insufficient, carbohydrates will be deposited in vegetative cells which will cause them to thicken. Excessive nitrogen fertilization reduces the sugar content of sugar beets. However, if nitrogen is available and conditions are favourable for growth, the carbohydrates are converted into proteins and then protoplasm. A plant deficient nitrogen, becomes stunted and yellow in appearance. This yellowing, or  chlorosis usually appears first on the lower leaves, the upper leaves remain green. In case of severe nitrogen shortage the leaves turn brown and die. Plant growth is thus hindered with marked effect on crop yield.