Not aimed at anyone in particular, eat whatever diet you want but don't think you are a better person being a veggie or vegan, because if you live in the UK your lifestyle is massively exploitive. Our generation - the elderly exploit the environment most of all just using the NHS is massively polluting when you considers all the workers contributing to care.
Fertilizers
I have travelled a lot in the poorest countries, nothing is wasted droppings are used as fuel, yes, cow pats are dried and you cook your supper using them.
Artificial fertilizers are used to increase yield, assuming the government is competent enough to distribute them - many aren't. The price of basic food is usually government controlled, the grower has no incentive to buy fertilizer beyond local needs.
It's very difficult at present with the Gulf War fertilizer is very expensive governments just don't have the money to buy enough so shortage and high prices is widespread.
Rural areas are better off they can subsist using what organic waste they have to compost and provide some fertility, without artificial fertilizers they can't produce a surplus. So they just barter for the essentials they can't grow. If you are old without family to help you rely on your garden to produce the food you eat, when you can't do that --.