Frits are melted soluble glass particles containing measured quantities of micronutrients like copper, iron, boron, zinc, manganese and molybdenum. Impregnated and granulated powdered glass is mixed with appropriate fertilizers so that a complete fertilizer is formed to render its application more complete. Such a complete fertilizer is useful when nutrients are required to be released slowly. In sandy and humid areas, where micronutrients tend to be lost by leaching, frits have become particularly useful. Frits are made by fusing salts of micronutrient elements with glass (soda glass or borosilicate glass) or glass components like feldspar, soda ash, silica, flurospar, cryolite, sodium nitrate and borax, and then powdering them before mixing with desired fertilizers. Melting the ingredients and rapidly cooling them by pouring into water or onto water-cooled steel rolls form frits. They are easy to handle, relatively inert and mixable with fertilizers without affecting the product stability; their solubility is governed by the particle size. There are other advantages of fritting, such as its ability for effecting (a) more even distribution of nutrient, (b) reduction in loss of volatile materials, and (c) conversion of poisonous materials (lead compounds) into their less dangerous forms. Frits are effective as soluble micronutrients for many crops like cotton, corn and peaches. Frits are identified by the micronutrient present in them, for example, copper frits when copper is present. Similarly, there are boron frits, zinc frits, molybdenum frits, manganese frits, iron frits, etc.
