There are sixteen essential elements needed for plant growth, which can be divided in two main groups: the elements obtained from the atmosphere (C,H,O) and the ones obtained from the soil (H2O, B, Ca, Cu, Cl, Fe, Mg, Mo, Mn, N, P, K, S and Zn) (FAO, 2019). The primary nutrients for plant growth are those required in the largest quantities amongst all, which are N, P and K (de Boer et al. 2018).

A fertile ecosystem is characterised by the presence of a balanced proportion of all essential nutrients for plants, which should be present in an available form. The lack of any of these nutrients hinders optimal growth. Nutrients are naturally lost from the environment as a result of erosion, removal of crops, leaching, etc. In fact, nutrient balance tends to be negative in almost all agricultural conditions due to the big quantities removed during the harvest, which has serious effects on plant growth. Hence, fertilizers are added to the soil to provide the plants with nutrients with the ultimate goal of sustaining and enhancing plant growth (FAO, 2019).

Fertilizers are classified into five major categories according to their composition.

Table 1: Fertilizer categories.
Fertilizer type Composition
Straight fertilizer Contain only one of the three primary nutrients N, P or K
Compound fertilizers Contain more than one of the three primary nutrients
Ca, Mg, Na, S fertilizers Composed of one or more of these elements and do not contain N, P nor K
Trace element fertilizers Made up of one or more trace elements but do not contain N, P, K, Ca, Mg, Na or S
Inorganic soil conditioners Are composed of Ca, Mg or both with the ultimate goal to maintain or rise the pH of the soil. S and gypsum can be used as conditioners for alkaline soils

It has been estimated that by the middle of this century our world will be home to nine billion people, and thus implies there is the urge to increase global food production by 70% to meet global demand by 2050 (Cordell et al. 2009), (UN DESA 2009). Rising demands for enhancing crop production will require higher quantities of fertilizers and ultimately the three primary nutrients (Cordell et al. 2009), (Long et al. 2015). According to the Food and Agriculture Organization of the United Nations (FAO), the world demand of the primary nutrients for 2022 will reach 200.919 thousand tonnes (Table 1) and predictions made in Cordell expect the phosphorus global demand to have an annual 2% increase until 2050 (Cordell 2010) (FAO 2019).

Current approaches to mining make phosphate a limited resource towards the end of the century, which presents a problem for future generations.

Table 2: Global demand for nitrogen, phosphorus and potassium for fertilizer use, 2016 to 2022 (thousand tonnes).
Based on World Fertilizer Trends and Outlook (FAO, 2019).
Cordell, D., Tina schmid-Neset, Stuart White, J. D. (2009). International Conference on Nutrient Recovery from Wastewater Streams, 2009,. Preffered Future Phosphorus Scenarios: A Framework for Meeting Long Term Phosphorus Needs for Global Demand, 23–43. Retrieved from

Cordell, D. (2010). The Story of Phosphorus Sustainability implications of global phosphorus scarcity for food security. Environmental Studies. Retrieved from

Cordell, D., Drangert, J.-O., & White, S. (2009). The story of phosphorus: Global food security and food for thought. Global Environmental Change, 19(2), 292–305.

de Boer, M. A., Wolzak, L., & Slootweg, J. C. (2018). Phosphorus: Reserves, production, and applications. Phosphorus Recovery and Recycling.

Food and Agriculture Organization of the United Nations (FAO). (2019). World Fertilizer Trends and Outlook to 2022.

Growing at a slower pace, world population is expected to reach 9.7 billion in 2050 and could peak at nearly 11 billion around 2100 | UN DESA | United Nations Department of Economic and Social Affairs. (n.d.). Retrieved March 24, 2020, from

Long, S. P., Marshall-Colon, A., & Zhu, X. G. (2015). Meeting the global food demand of the future by engineering crop photosynthesis and yield potential. Cell, 161(1), 56–66. White, J. (2000). Introduction to Biogeochemical Cycles. In (Ch. 4) (p. Department of Geological Sciences, University of C).