I did not know this! Apparently, they have achieved this by using methods like aquaponics to obtain high yields. So what are they producing? I suspect it would mostly be flowers, fruits and vegetables. Faced with scarce land, the Dutch made smart use of water. faced with a water shortage , partly due to a warming planet, we need to think about drought resistant varieties of crops such as this initiative with maize in Uganda.
via Population Density Fact Of The Day: The Netherlands Is An Agricultural Exporter.