Common zinc fertilizer raw materials mainly include: heptahydrate zinc sulfate, monohydrate zinc sulfate, hexahydrate zinc nitrate, zinc chloride, EDTA chelated zinc, zinc citrate, and nano zinc oxide.
1. Zinc Fertilizer Raw Materials
- Zinc sulfate: Colorless or white crystals, granules, and powder with no odor. Melting point: 100°C, with astringent taste. Density: 1.957 g/cm³ (25°C). Easily soluble in water, the aqueous solution is acidic, and slightly soluble in ethanol and glycerol.
- Zinc nitrate: Colorless crystal in the tetragonal system, hygroscopic, should be stored in the dark. Melting point: 36°C, boiling point: 105°C, density: 2.065 g/cm³.
- Zinc chloride: Melting point: 283°C, boiling point: 732°C, density: 2.91 g/cm³. Appears as a white crystalline powder, easily soluble in water, soluble in methanol, ethanol, glycerol, acetone, and ether, insoluble in liquid ammonia, with a solubility of 395 grams at 20°C.
- Zinc oxide: Also known as zinc oxide powder, zinc white, or zinc white powder, is an inorganic compound with the chemical formula ZnO and a molecular weight of 81.39 g/mol. It is a white solid and a form of zinc oxide. Zinc oxide is insoluble in water and ethanol, but soluble in acids, sodium hydroxide solution, and ammonium chloride. It is an amphoteric oxide and can react with acids or bases to form salts and water.
- EDTA zinc: Sodium ethylenediaminetetraacetate zinc, also known as EDTA disodium zinc, EDTA chelated zinc, EDTA-Zn 14%, with a pH (1% water soluble) of 6.0-7.0. Appearance: white powder.
- Zinc citrate: Also known as citric acid zinc, zinc yellow, or tri-zinc citrate, is slightly soluble in water; soluble in dilute acid solutions and alkaline solutions, appearing as a colorless powder, tasteless, and slightly soluble in water, with a solubility of 2.6 g/L.
2. Functions of Zinc in Crop Nutrition
Zinc primarily serves as a component and activator of certain enzymes, playing an important role in the hydrolysis, redox processes, and protein synthesis of substances within crops. It can promote the development of reproductive organs in crops and enhance their resistance to stress. Zinc is an essential trace element for plants, with zinc content generally ranging from 20-100 mg/kg. When the zinc content drops below 20 mg/kg, symptoms of zinc deficiency may occur.
Zinc is a component of various enzymes, including superoxide dismutase, catalase, and carbonic anhydrase, and participates in the metabolic activities of plant auxins, proteins, carbohydrates, and other substances, playing a critical role in maintaining normal plant growth. In auxin metabolism, the synthesis of IAA’s precursor, tryptophan, requires zinc, and zinc deficiency can reduce the auxin content in maize root tips by 30%, affecting root growth. In protein metabolism, zinc deficiency leads to reduced RNA stability, affecting protein synthesis. Research shows that applying zinc fertilizer can increase protein content in milled rice by 6.9%.
In carbohydrate metabolism, zinc promotes chlorophyll synthesis and enhances the activation of carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase, facilitating the carbon assimilation process. Zinc also plays an important role in scavenging reactive oxygen species in plants and improving their stress resistance. In the early growth stages of rice, applying zinc can significantly reduce the damage caused by low temperatures to rice seedlings. Zinc deficiency in rice mainly occurs during the seedling stage, manifesting as stunted growth and dwarfing, with the base of the leaves turning white, slow growth, reduced tillering, and in severe cases, brown spots appearing on the leaves.
Post time: Jan-20-2025
