Nitrogen is the most essential element for plant growth and production. Nitrogen fertilizers are used in different farms and greenhouses to improve soil fertility, crop yield and the quality of products. Also, the use of these fertilizers help to improve soil structure, increase ventilation and soil moisture. These fertilizers contain nitrogen as their main component, in the forms of, urea, No3 or NH4 , which can provide nitrogen for plants.

When the plant is facing nitrogen deficiency, it has a very low and weak growth, the leaves are yellow-green and wither and finally the number of branches and plant yield will reduce. When the plant is facing with excess nitrogen, the growth is more lush and the leaves are dark green but the plant often suffers from different diseases and insects. For example, in cereals, the grains are not often full and the probability of secret grains appearing becomes larper. Excessive use of nitrogen fertilizers may lead to groundwater pollution and environmental problems. Thus, optimal and balanced use of nitrogen fertilizers is very important to maintain the balance of soil and environment.

The best way to use nitrogen fertilizer is before planting and after determining the amount of soil nitrogen through soil tests. These fertilizers can be used in the form of direct application to the soil, dissolved in irrigation water or foliar spraying in order to better absorb nitrogen by the plant.