Glyphosate, as a non fungible herbicide, is currently one of the most widely used herbicide varieties. Glyphosate has the characteristics of non selectivity and no residue, and is very effective against perennial weeds. It is widely used for weed control in orchards, rubber trees, and wastelands. After absorption by stems and leaves, it is transmitted to various parts of plants, inhibiting the synthesis of enolacetone based glyphosate phosphate synthase in plants, thereby inhibiting the conversion of glyphosate to phenylalanine, tyrosine, and tryptophan, interfering with protein synthesis and leading to plant death.
Glyphosate has many varieties, and the earliest used glyphosate was mostly a 10% glyphosate water solution, which was very cheap. 10% glyphosate water solution is actually an industrial wastewater prepared by adding the mother liquor from glyphosate raw material production. It contains a large amount of heavy metals and sodium chloride, which causes great pollution to the environment and soil. Long term use can easily cause soil salinization and severe compaction, and has a strong toxic effect on subsequent crops. Therefore, it is explicitly prohibited from production by the state. Since the delisting of 10% glyphosate water solution, glyphosate ammonium salt, glyphosate isopropylammonium salt, and glyphosate potassium salt water solution have gradually become mainstream products in the market.
The broad definition of glyphosate refers to a general term for various glyphosate salts, while the narrow definition of glyphosate refers to glyphosate acid (which is also the part that truly works when weeding). It is acidic and difficult to dissolve in water, but its salt is easily soluble in water. Therefore, in actual production and use, it needs to be converted into salt to increase its water solubility. Salt can include potassium salt, sodium salt, ammonium salt, isopropylammonium salt, etc. Glyphosate ammonium salt, glyphosate isopropylamine salt, and glyphosate potassium salt are obtained by reacting glyphosate acid with ammonia gas, organic base isopropylamine, and a base containing potassium cations, respectively. The content of glyphosate in 33% ammonium salt, 41% isopropylammonium salt, and 37% potassium glyphosate salt is 30%, and their herbicidal active groups are the same. However, different salts have differences in the absorption process of plants, which affects the efficacy of glyphosate. According to the experimental data provided by the Ministry of Agriculture of China, the order of herbicidal activity is: glyphosate potassium salt>glyphosate isopropylammonium salt>glyphosate ammonium salt>glyphosate sodium salt.
The main characteristics of several glyphosate salts are as follows: ammonium salts have low cost and low price, but the disadvantage is slightly poor stability and unsatisfactory low-temperature effect; Isopropylamine salt is easily absorbed by weed leaves, has a fast toxic reaction, and has good low-temperature properties (especially suitable for use when the average temperature is below 22 ℃). The disadvantage is that the cost is relatively high and the effect on deep rooted crops is not ideal; Glyphosate potassium salt has high solubility and good moisture absorption. During use, it has a secondary absorption and conduction effect, which can improve the effective utilization rate of glyphosate, weed control more thoroughly, and also has the effect of supplementing potassium fertilizer. The disadvantage is that it is relatively expensive. Therefore, when farmers make purchases, they cannot simply judge that 37% or 41% of products are better than 33%. They should pay attention to the effective ingredients labeled on the product label and choose according to their actual needs. If it is used on a large scale to control general weeds, ammonium salts can be used to save costs; In areas with relatively low temperatures, it is recommended to use isopropylammonium salt, while for deeply rooted weeds such as reeds, or in arid areas and potassium deficient soils, it is recommended to use glyphosate potassium salt.
