The pie chart 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

The pie chart provides the main features attributed to less productive agricultural land, while the table compares these causes in terms of three different areas of the world in the 1990s.
Overall, overgrazing was the biggest contributor to worldwide land degradation. Europe was the region with the highest percentage of total land degraded, caused most by deforestation.
It can be seen clearly from the first graph that overgrazing was the main reason, accounting for 35% , followed by deforestation at 30%, respectively. Over-cultivation contributed four times as much as other factors to land degradation.
To turn to the second chart, Europe had a significantly large proportion of total land degraded, caused by 9.8 deforestation, 7.7 over-cultivation, and 1.5 over-grazing, respectively. The figure for Europe was nearly quintuple that of North America. The rate of deforestation in North America accounted for 0.2%, 3.3% over-cultivation, and 1.5% over-grazing.
By contrast, Oceania was the only region in which agricultural land became less productive due to two causes: a 1.7 percent deforestation rate and 11.3 percent overgrazing.