I want to get into organic farming methods but I have a nagging philosophical question that won't go away. I can see that applying energy intensive chemical methods of inorganic fertiliser is an unsustainable system but can't the same argument be applied to organic nutrient sources. Let us take the situation where your own a piece of bare land that is deficient in one or more macro or micronutrients. Your intention is to build up the soil structure, organic content and nutritional value of the soil. If one takes an organic approach then you are obligated to import various quantities of various products. These may include manures, crop residues, sea-bearing vegetation and mineral dust. The nutrients contained within will need to be removed from an external system. How will these be replenished? I will give an example. A crop is grown on fertile soil extracting the nutrients contained within the soil. A grazing animal eats the crop and uses the nutrients for growth and development (locking it up in its body structure). A portion of these nutrient are excreted as waste. The owner collects the nutrient-containing manure and exports it to a local organic grower. The law of economics and conservation suggests this cannot continue indefinitely. Eventually the original site is robbed of its nutrient content (unless it also obtains nutrient sources from another location). I have heard mentioned that there are a number of nutrients already within a local system which can be accessed deeper in the subsoil by certain plants e.g. comfrey. Are these plant 'foragers' able to extract sufficient nutrients to replenish the upper layers? Is it possible that even in the most of barren of soils there are enough nutrients that can lifted up out to make the area self-sustaining. At the moment it doesn't quite add up.