The pie chart shows that there are four main causes of farmland becoming degraded in the world today. Globally, 65% of degradation is caused by too much animal grazing and tree clearance, constituting 35% and 30% respectively. A further 28% of global degradation is due to over-cultivation of crops. Other causes account for only 7% collectively.
These causes affected different regions differently in the 1990s, with Europe having as much as 9. 8% of degradation due to deforestation, while the impact of this on Oceania and North America was minimal, with only 1. 7% and 0. 2% of land affected respectively. Europe, with the highest overall percentage of land degraded (23%), also suffered from over-cultivation (7. 7%) and over-grazing (5. 5%). In contrast, Oceania had 13% of degraded farmland and this was mainly due to over-grazing (11. 3%). North America had a lower proportion of degraded land at only 5%, and the main causes of this were over-cultivation (3. 3%) and, to a lesser extent, over-grazing (1. 5%).
Overall, it is clear that Europe suffered more from farmland degradation than the other regions and the main causes there were deforestation and over-cultivation. 
The pie chart  
shows
 that there are four main  
causes
 of farmland becoming degraded in the world  
today
. Globally, 65% of  
degradation
  is caused
 by too much animal grazing and tree clearance, constituting 35% and 30%  
respectively
. A  
further
 28% of global  
degradation
 is due to over-cultivation of crops. Other  
causes
 account for  
only
 7%  
collectively
.
These  
causes
  affected
  different
 regions  
differently
 in the 1990s, with Europe having as much as 9. 8% of  
degradation
 due to deforestation, while the impact of this on Oceania and North America was minimal, with  
only
 1. 7% and 0. 2% of land  
affected
  respectively
. Europe, with the highest  
overall
 percentage of land degraded (23%),  
also
 suffered from over-cultivation (7. 7%) and over-grazing (5. 5%).  
In contrast
, Oceania had 13% of degraded farmland and this was  
mainly
 due to over-grazing (11. 3%). North America had a lower proportion of degraded land at  
only
 5%, and the main  
causes
 of this were over-cultivation (3. 3%) and, to a lesser extent, over-grazing (1. 5%). 
Overall
, it is  
clear
 that Europe suffered more from farmland  
degradation
 than the other regions and the main  
causes
 there were deforestation and over-cultivation.