Liquid fertilizer solutions and fluid fertilizers are popular in many areas because they’re safe to handle, convenient to mix with other nutrients and chemicals, and are easily applied. A solution of urea [CO(NH₂)₂] and ammonium nitrate [NH₄NO₃] containing between 28 and 32 percent nitrogen (N) is the most popular fluid N fertilizer.
Many soils require adding several essential nutrients to alleviate plant deficiencies. Farmers may opt to select a combination of single-nutrient fertilizers or apply a fertilizer that combines several nutrients into each particle. These combination fertilizers (compound or complex) can offer advantages of convenience in the field, economic savings and ease in meeting crop nutritional needs.