The area of break crops on farm: What farmers are doing compared to estimates based on maximising profit

• Break crops increase farm profit, although in some cases the optimal area for break crops on the farm is small. There is an upper limit to break crop area beyond which whole-farm profit drops—i.e. more is not necessarily better. • The response of whole farm profit to per cent of the farm allocated to break crops is relatively flat. This result highlights, at least in economic terms, why adoption of break crops is highly variable within one rainfall zone. • The modelled area of break crops at maximum profit is higher than that found in farm surveys and can be explained in part by lower break crop yields being realised by farmers but also raises questions about farmer motivations for adoption of break crops. • The scope for increased area of broadleaf break crops beyond 35 to 40% of the farm is limited, even if the yield boost they provide to cereals increases. There are risks to break crops dropping out of the system if yield boosts to cereals and yields of the break crops themselves are less than assumed in current whole-farm economic models.