What is the definition of organic fertilizer?

 　　Manure is a kind of fertilizer made of natural organic matter decomposed or fermented by microorganisms.It is also called farmyard fertilizer in China.Its characteristics are:wide source of raw materials and large quantity;Complete nutrients and low content;The fertilizer effect is late and long,and can only be absorbed by plants after being decomposed and transformed by microorganisms;The effect of soil modification is good.The commonly used natural fertilizers include green manure,human manure,manure,compost,compost,biogas fertilizer and waste fertilizer.