Lord Melchett points out for example that the artificial fertiliser used in conventional farming is made using natural gas, which is "completely unsustainable".

罗德迈彻特举例指出，传统耕作方式中使用的人造化肥由天然气制造，而天然气是“完全不可再生的”。

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This has meant that we have had to buy in artificial fertiliser instead, which could delay the planting process further.

BBC: A farmer's diary: Returning to normal

All organic crop rotations contain three to four years of no ploughing because grass leys use the sun's energy to fix nitrogen for subsequent crops in place of oil-based artificial fertiliser.

ECONOMIST: Organic matter