Microelement fertilizer refers to the fertilizer containing microelement nutrients. Trace elements include boron, zinc, molybdenum, iron, manganese, copper and other nutrients. Although plants need little trace elements, they play the same important role in the growth and development of plants as a large number of elements. When some trace elements are lacking, the growth and development of crops are obviously affected, the yield and quality of crops are reduced.

On the other hand, too much microelements will cause crop poisoning, which will affect the yield and quality of crops, and even endanger the health of people and animals. With the continuous increase of crop yield and the application of chemical fertilizer, the application of microelement fertilizer is becoming more and more urgent.

The micro fertilizer that will be popularized or applied in China includes: boron fertilizer, molybdenum fertilizer, zinc fertilizer, copper fertilizer, manganese fertilizer and iron fertilizer. They are used in crops, trees, pastures, fruit trees and vegetables, all of which can not be replaced by each other. Application of micronutrient fertilizer to nutrient deficient soil and sensitive plants can increase production significantly.

According to the types of micro fertilizer compounds, they can be roughly divided into five categories:

(1) Soluble inorganic salt. Most of these fertilizers are sulfate.

(2) Insoluble inorganic salt. Most of them are phosphates and carbonates, and some of them are oxides and sulfides. For example, zinc ammonium phosphate, zinc chloride, etc. Suitable for base fertilizer.

(3) Glass fertilizer. Most of them are silicate powder containing trace elements, which are sintered or melted at high temperature. It is a glassy substance, such as slag of smelter, which can only be used as base fertilizer.

(4) Chelate fertilizer. It is a natural or synthetic chelating compound, chelating with trace elements, such as zinc chelate.

(5) Industrial waste containing trace elements.