With the increasing popularity of water-soluble fertilizers with major elements, the market is filled with various products of different qualities, which makes many growers face difficulties in selection. Choosing high-quality WSF is the key to ensuring fertilization effect and crop safety. To this end, growers need to remember the "four checks and one test" principle and avoid falling into the trap of "hormone fertilizers".

The first check is to look at registration certificates and standards. Legitimacy is the bottom line of choosing WSF. All commercial WSF must obtain the fertilizer registration certificate issued by the agricultural and rural department, and growers can query the authenticity on the official website. For unregistered products, the quality and safety cannot be guaranteed and they should be avoided. At the same time, it is necessary to read the product standards clearly: the water-soluble fertilizers with major elements must comply with the NY 1107-2020 standard, which clearly requires that the sum of nitrogen, phosphorus and potassium contents is ≥50%, and the content of a single major element is not less than 4%. Products that do not meet this standard are unqualified.

The second check is to look at nutrient formulas and forms. It is necessary to choose the appropriate formula according to crop needs. WSF is mainly divided into three types: major element type (providing basic nutrients such as N, P and K, which is the "staple food" of crops), functional type (adding humic acid, alginic acid, amino acid, etc., which plays a role in improving soil and enhancing stress resistance, and is a "health product" that cannot replace the staple food), and medium and trace element type (targeting calcium, magnesium, boron, zinc and other elements to solve nutrient deficiency symptoms). In addition, attention should be paid to solubility and impurities: high-quality WSF dissolves quickly in water, the solution is clear, and there is no residue at the bottom. The trace elements in chelated form (such as EDTA and EDDHA chelated calcium and iron) are more stable and easier to be absorbed by crops, especially suitable for hard water or alkaline soil.

The third check is to look at raw materials and production processes. The raw material grade directly determines the product quality. WSF made of food-grade or industrial-grade raw materials (such as potassium dihydrogen phosphate and potassium nitrate) has high purity and low heavy metal content, which is safer for crops and soil. The production process (chemical synthesis or physical mixing) affects the uniformity of nutrients and water solubility. Products from well-known manufacturers usually have more reliable production lines and better product quality.

The fourth check is to look at brands and technical services. It is recommended to choose regular brands with R&D strength and good reputation. These brands can usually provide scientific fertilization guidance, including the dosage, dilution ratio and application frequency of different crops in different periods, which is crucial to giving play to the effect of water-fertilizer integration.

The "one test" refers to conducting a small-scale comparative test before large-area application. By comparing the long-term effects (yield, quality, soil status) of different products on a small area, instead of only focusing on the short-term growth, we can accurately judge the quality of WSF. At the same time, it is necessary to be alert to the trap of "hormone fertilizers". Such products usually add a lot of plant growth regulators but have insufficient nutrient content. They take effect quickly but have unsustainable effects, which will lead to excessive growth of crops, poor flower bud differentiation, premature senescence, deformed fruits and other problems, and even damage the soil.