ABSTRACT
Global fertilizer supply has increased drastically since 1960. The present global fertilizer supply (N+P2O5 + K2O, 106 Mg) for 2015–2020 indicates an increasing trend of 1.46%/yr over the 6-year period. However, the rate of increase in global fertilizer consumption was 5.5%/yr between 1960 and 1990 and 2.9%/yr between 1990 and 2020. Among all fertilizers, the annual rate of growth of N was 7.1% between 1960 and 1990 compared with 4.4% between 1990 and 2020. The annual rate of fertilizer growth between 1990 and 2020 has been especially high for Asia (i.e., China, India) but has lagged behind in Sub-Saharan Africa (SSA). Thus, the agronomic yield of crops in SSA has also stagnated, and the small rate of growth in some regions is much lower than its technical potential (Lal 2017). While the growth rate and the total global consumption of fertilizers have increased, the use efficiency of fertilizer has remained low, especially that of the nitrogenous (N) fertilizer. In developing countries and also in emerging economies (i.e., India, China), the use efficiency of N fertilizers can be as low as 30%. Therefore, a large proportion of the reactive N is leaked into the environment (water and air) with dire consequences.
