Trend of fertilizer application during the last three decades (Case study: America,Australia, Iran and Malaysia)

The use of chemical fertilizers in four countries (Iran, Malaysia, Australia and US) was compared over a period of 30 years. Results showed that the use of nitrogen as a nutrient in Australia, Iran and Malaysia had a wide change due to the population growth and the need to provide food for the community. By growing the trend of urbanization, the ratio of population parameters of arable land has been reached from 3 ha/person in 1980 to less than 2 ha/person in 2010. Finally, the ratio between the main nutrient elements in Iran, Malaysia, the US and Australia was 100-70-0.2, 100-80-145, 100-43-51 and 100-329-100 in 2010, respectively. Regardless of the specific reasons and differences in sources of soil, crop and climate in these countries, the ratio in US is much closer to the balance of plant and stabilizes the long optimum ratio during the period.