The global human population reached 8 billion on November 15, 2022. According to the World Population Prospects 2022, it will grow to 8.5 billion in 2030, reaching 9.7 billion in 2050. This requires a sustainable agriculture system with efficient use of water, energy and nutrient resources, a reduction of environmental impacts, maintaining economic strength and minimizing dependence on finite depleting resources. Fertilizers are necessary to replace nutrients that are depleted from the soil when plants are grown. The most prevalent nutrients for fertilizers are nitrogen, phosphorus, and potassium, with calcium, magnesium, sulfur, boron, copper, manganese, molybdenum, and zinc added less often or in lower amounts as micronutrients. Nitrogen is supplied in many forms -it can be supplied alone (e.g: as anhydrous ammonia, urea, urea-ammonium nitrate, etc.), or in combination with phosphorus (e.g: monoammonium phosphate or in struvite). Phosphorus is commonly supplied as phosphates, including more complex phosphates such as struvite or the calcium phosphate hydroxyapatite (Ca5(OH)(PO4)3. Potassium, when needed alone, is used as potassium sulfate or potassium chloride. The forms in which the nutrients are supplied and when they are provided to crops are important in determining how effectively the nutrients are used by the plants.