What is the ruling on buying and selling animal waste as agricultural fertilizers, including the costs of transporting it over long distances?

It is permissible to sell animal waste as fertilizer, whether it is from animals whose meat is eaten (due to its purity) or from animals whose meat is not eaten (due to the need for it). It is also permissible for the buyer to stipulate that the seller deliver the sold item to a specific location, because this is one of the valid conditions in a sale, such as stipulating the transport of a camel to a known place. This is known as combining sale and hire (ijarah), provided that the stipulated benefit is known.