Requirements for animal manure for conversion to organic farming
Please can someone point me in the direction of any research that has looked at how much extra (if any extra) animal manure would be required if we were to convert to near 100% organic farming? It seems to me that a main point of focus within organic farming is the exclusion of synthetic or inorganic fertilisers, with a strong reliance on animal waste as a source of fertiliser. So if we converted to almost total organic food production (however theoretical that supposition might be), how would that impact livestock production? I have always assumed that we produce enough livestock globally to service this fertiliser requirement, but it has occured to me that this is purely an assumption I have made... I am not a total advocate of organic farming anyway, but am very interested in the food system consequences of a major conversion to organic farming. Would we need more livestock, or could the extra organic fertiliser come from other sources anyway (humans, crop residues, nitrogen fixing crop rotations etc etc)? And what are the GHG impacts of this theoretical livestock number? It seems to me this would be a key factor in identifying the actual best practices for food production, rather than just the "organic vs conventional" arguments that persist... Any help and advice much appreciated. If there are no answers, maybe I will bookmark this idea for a future phd when I have tired of working in the commercial side of food sustainability, ho ho ho.