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UN warning over future of crop growing

29 November 2011 Last updated at 03:30 GMT

The world may not be able to properly feed itself by 2050 - that is the stark warning from a UN report which suggests a quarter of the world's land surface is now severely degraded and may not be able to grow enough crops for a rising population.

The report blames a combination of climate change and poor farming practices.

Bill Hayton reports.