Make the sentence fluent: Deforestation, over-cultivation, over grazing and other activity are the principal causes upon why agricultural lands becoming less productive deforestation is the second main cause against 30% which is the principal cause behind land degradation despite Europe, it having less consequence in North America, where it was the third cause at this region, and in Oceania it was only the second cause reaching 1.7% of that regions.
Deforestation, over-cultivation, over-grazing and other activities are the principal reasons why agricultural land becomes less productive. Deforestation is the second major cause with 30% and is the principal cause of land degradation in Europe, it had less impact in North America, it was the third cause for this region, and in Oceania it was only the second cause, affecting 1.7% of that region.