@oriole I started the food forest with a no dig garden, that is I put down cardboard on the existing soil and then layered it with green cuttings, paper, compost and some brought soil. I have since continually added layers of green waste, limited woodchips (they can be acidic) sugar cane mulch and daily I dig in all my vegetable scraps. In regards to nitrogen I do grow pigeon peas which are nitrogen fixers. In short like most people on limited budgets I use whatever I cut down, lawn clippings etc to continually enrich what I already have. When I was a community garden member I saw some people spend a lot on store brought additives but I think it is really about continually working it with whatever you have on hand.Also I swale all the water runoff in my garden down to the food forest and this helps greatly. I do hopes this helps. One thing I do buy is a seaweed additive. My father always used to gather kelp from the beaches in New Zealand's south and dig it into our vegetable patch. if something looks a little fragile its always gets some seaweed solution.