I'm putting together a plan for a fruit wine business, and need to calculate expected yields for fruit trees each year from the date of planting. I have found various resources that provide 'time to first fruiting' and 'yield at maturity', but rarely can I find information stating the yield at first fruiting and the time to maturity. Without these pieces of information, it is impossible to estimate expected yield from year to year.
I am aware of how hopelessly imprecise any such calculations would be; locality and climate clearly have a large impact. Nevertheless, I need to show some figures from an authoritative source to provide a rough estimate for year-on-year production. Given the four pieces of information above, I could assume a linear increase in yield from the first fruiting until maturity.
Does anyone know of a reliable source of such information for fruiting trees? I am based in the UK, so ideally am looking for a resource relating to temperate climates.
Edit: To provide some logic for asking this question: our local government allows people to establish smallholdings if they can provide a business plan for a land-based enterprise. These business plans are heavily scrutinised, so although I recognise that any figures are likely to be imprecise, so long as they are from a reputable source, they would provide a 'ballpark' estimate of year-on-year yield from various crops. We can then base our business plan around, for example, a very poor year in which only 30% of the expected crop is yielded.