There are many different types of nitrogen fertilizer available. The main two types are urea (N46. and ammonium nitrate (AN). They differ in how quickly they are released into the soil, and how fast the plant will use them. Ammonium Nitrate Ammonium nitrate is a slow-release fertilizer that increases the amount of N in the soil, making it available to the plants for a longer period of time. Ammonium nitrate is also called AN or ammonium nitrate fertilizer. It contains nitrogen, phosphorus, and potassium. The N content is usually from 10% to 50% and is sometimes called “nitrogen-rich” fertilizer. It is used for lawns and greenhouses. Ammonium nitrate can be applied at rates of 25 pounds per 1,000 square feet. Ammonium nitrate can be spread on the surface or incorporated into the soil by mixing with other fertilizers, compost, or soil amendments. Ammonium nitrate can be applied in liquid form, a dry granular form, or as an organic fertilizer. Fertilizing with ammonium nitrate will make more nitrogen available in the soil than if you just apply fertilizer without it. The amount of fertilizer you need depends on your climate, soil type, and crop type. It is also important to add phosphorus and potassium to the soil to balance the amount of nitrogen and phosphorus in the soil. Urea is a fast-release fertilizer that increases the amount of N in the soil for a short period of time. It has a higher N content than ammonium nitrate and is usually applied at rates of 12 to 20 pounds per 1,000 square feet. Urea is usually applied when the plants are actively growing.