The pie charts below shows the main reasons why agricultural land becomes less productive. The table shows how these causes affected three regions of the world during the 1990s

These figure shows the significant reasons of less productivity of agricultural land worldwide and the percentage of land degradation in three regions in 1990.

Overall, it can be seen from the pie chart the main reason of land degradation was over-grazing of animals, accounted for 35%. It is followed by deforestation by human beings which is 5% less than over-grazing. The third caused for land becoming less productive was over-cultivation, which constitutes 28%. The other non-specific reason of global land degradation stood at 7%.

Europe has the highest percentage of land degraded for about 23% in comparison with Ocenia which comprised of a large group of islands in the South Pacific including New Zealand and Australia and North America with percentage of 13% and 5% respectively. Moreover, agricultural land degradation in Europe mainly caused by deforestation. In Oceania, the main reason why land becoming less productive was over-grazing and over-cultivation is not even a cause of land degradation. However in North America, over-cultivation was the significant factor of land degradation in 1990.