The main factors of agricultural land reduction in the world which are presented in the pie chart were over-grazing, deforestation, over-cultivation, and other reason. Related to the next table, it shows the percentage of land degradation which was caused by the factors in three zones during 1990s.
Overall, the biggest cause of global land degradation was over-gazing at 35 percent. At the time, over-gazing also was a factor which gave the highest percentage of reduction in Oceania. However, compared to other region, Europe had a largest area of land degradation at 23 percent, followed by Oceania at 13 percent, and the last was North America at 5 percent.
The biggest factor which caused the largest land of the reduction in Europe was deforestation at 9.8 percent, while it was over-cultivation in North America at 3.3 percent. In Oceania, the most reason caused the degradation of agricultural land was over-grazing, with the percentage of land degraded was 11.3 percent. However, it was an interesting fact in Oceania that over-cultivation gave no contribution to the degradation of land while it was quite influential in both North America and Europe.