Monica
Most of the crops grown in the UK already receive the optimum plant nutrients, all farmers have to use a qualified agronomist to calculate what is needed and advise on any chemical treatment. Every application is recorded on every field, audited and also available for inspection at any time.
That is the fact of crop production and the same applies to livestock.
Organic production of crops cuts yields by at least 2/3 because fertility has to be built up either by livestock or green manuring and it may take 3 years before a crop of Wheat can be grown.
Grazing livestock is fairly straightforward use a larger area and manage manure efficiently and you can be organic quite easily
Intensive livestock, Pigs, Poultry and some Cattle, all would be fed on a cereal based diet, that becomes very difficult. Organic cereals would be very expensive and prices would increase greatly, probably to unaffordable levels for many.
Reducing animal production also reduces the manure that crops use to grow, so even more chemical fertilizers are needed to maintain crop production, that means more CO2 to make the chemicals.
Don’t get hung up on soils degrading and widespread erosion, look around the countryside and you will see lush healthy crops, damage by bad soil condition is minor, adverse weather influences crops far more.
On a Global level less than half of the population would be able to be fed by organic production, it’s the technology and chemicals that feed the rest. We in the affluent west can afford to choose organic if we wish, however the population is growing and living longer so the bulk of food is not going to be grown organically.