In Organic agriculture, unlike most other forms of agriculture, you can not use fossil fuels fertilisers so have to find other ways of giving nitrogen principally to crops. This is achieved by several ways; including crop rotation by planting things like alfalfa that puts nitrogen back in soil and is used as fodder for livestock. Or by applying handmade concoctions (mixed in with animal manure – a time and tested ancestral way of feeding plants with extra food).
In the Cooperatives in Altiplans they have been using Recipes passed on by grandmothers which are still in the early stages of optimising yields.
Here is the recipe for the Biol-homemade organic fertilizer:
Recipe for 60 litre vat: 15kg dung- best results if fresh and sheep/llama gives better results than cow dung. 20 chicken eggs. 20 litres cows milk. Phosphorite rock (for phosphorous), 4kg of fresh alfalfa, fill rest with water. Allow mixture to ferment for 3 months before applying to fields. Recommends minimum of 3 applications per season.
They also buy Guno, one of the worlds richest fertilizers. Made form bird poo scraped off the rocks of the Pacific Coast of Peru. It is sold internationally as one of the finest organic fertilizers.
They also use a homemade Pesticide/herbicide: made from a mixture of lime and sulphur: pretty much the oldest known crop application for treating mildew etc.