Organic farmers will soon have access to a computer program for estimating how much nitrogen is available to crops in the years following the ley stage of a rotation.

The development of the Fertility Building Crops computer model at IGER Aberystwyth, financed by DEFRA, will predict the nitrogen supply available to a range of crops under different growing conditions for up to five years after a ley. Users will also get an indication of where nitrogen is being wasted.

They will be expected to supply details of their UK region, rainfall and soil type, plus details of the ley, including type, age, legume content and management, and the date it was incorporated. Details of crops to be grown and manure applications will also have to be input before predictions are calculated.

The computer model is already working satisfactorily under developmental conditions, but an IGER team is making final revisions before it is released to the industry.