Letter: Briefly

SO Rothamsted scientists are sceptical that organic methods on their own can provide enough nitrates to fertilise crops and prevent the soil from becoming depleted. ('Not quite as organic as you think', 21 March). How then do they imagine agriculture has been sustained on this planet for centuries? Artificial 'aid' in the form of pollution from cars and power stations has been present only this century. Intensive agriculture and chemical fertilisers are more likely to prove unsustainable, reducing the soil to a lifeless substrate giving only physical support to plants.

M J Jones, Llantarnam, Gwent