Animal manures were the main source of organic fertilizer, but their application for fanning lands were limited due to a lot of pathogens, parasite ova and toxicant contained.

• 尽管畜禽粪便是有机肥料的主要来源，但是其携带的大量病原菌、寄生虫卵和有毒物质是影响畜禽粪便农田利用的主要原因。