Fertilizer synergists refer to a class of active substances for the purpose of increased nutrient availability.
It can increase the supply of crop nutrients by fixing nitrogen and activating phosphorus and potassium elements that are difficult to use in the soil and plays a certain role in regulating plant physiological functions.
It is usually added to conventional fertilizers, which can appropriately reduce the amount of fertilizer application and improve the utilization rate of fertilizers.
The most common product on the market at present: Polyaspartic acid (PASP), Gamma Polyglutamic Acid (γ-PGA), Gamma Aminobutyric Acid (γ-GABA), and Alginate oligosaccharide.

Related Researches
Humic acid, fish protein, amino acids, and seaweed fertilizer—which one is the best?
How γ-Polyglutamic Acid (γ-PGA) Improve Soil Health & Crop Growth
Synergistic effects of PGPR and amino acids on growth, productivity, and Nitrogen availability of edamame
Effect of poly (γ-glutamic acid) on wheat productivity, nitrogen use efficiency and soil microbes
The water retention effect of PGA and seaweed fertilizer on plants and soil
Paenibacillus mucilaginosus:activating soil nutrients, promoting nutrient uptake by crops, and enhancing stress resistance
The importance of nitrogen in plant nutrition and the application of biostimulants.
A compound of three major biostimulants: seaweed fertilizer, humic acid, and fulvic acid