What methods are there to tell good water-soluble fertilizer from bad?
Water-soluble fertilizer is actually a formula fertilizer, with different formulas prepared according to different crops, different soils and different water quality, so as to maximize the crop's nutritional needs, improve fertilizer utilization and reduce waste. Therefore, the formula is the key to telling good water-soluble fertilizer from bad.
Check the nitrogen, phosphorus and potassium ratio
Take the commonly used high-potassium formula as an example: according to the nutritional needs of general crops during the fruit-setting stage, a nitrogen : phosphorus : potassium ratio of 2 : 1 : 4 gives the best results, and different ratios will produce very large differences in effect.
Check whether the trace elements are complete and whether the ratio is reasonable
A good water-soluble fertilizer must contain all 6 trace elements, and must have a scientific ratio, because there is a problem of antagonism and synergy among the various nutrient elements. A water-soluble fertilizer is not good simply because the content of one or several elements is high; it is good only when the ratio is scientific and reasonable.
Check the content
Good water-soluble fertilizer uses industrial-grade or even food-grade raw materials, has very high purity, and does not add any fillers, so its content is relatively high, with 100% being nutrients that can be absorbed and used by crops, and the nitrogen, phosphorus and potassium content generally reaching 60% or even higher. Poor water-soluble fertilizer generally has low content; for every unit less of content, there will be a difference in cost, and the price of the fertilizer will also differ.
Check the water solubility
To identify the water solubility of a water-soluble fertilizer, you only need to dissolve the fertilizer in clean water and see whether the solution is clear and transparent. If, apart from the color of the fertilizer, it is the same as clean water, the water solubility is very good; if the solution is turbid or even has sediment, the water solubility is very poor, it cannot be used in drip irrigation systems, and there will also be more waste of fertilizer.
Smell the odor
Good water-soluble fertilizers are all made from high-purity raw materials and have no odor at all or a very faint fresh fragrance. Fertilizers with an off odor have either added hormones or contain too many harmful substances. Such fertilizers take effect very quickly when used, but water-soluble fertilizer brings no benefit at all to the crop's disease resistance or to sustained yield and quality.
Make a comparison
After preliminary screening of water-soluble fertilizers through the simple methods above, the next step is to make field comparisons and determine which water-soluble fertilizer to choose through actual application effects. Good fertilizer will not take effect too quickly, because nutrients have a process of absorption and transformation. A good water-soluble fertilizer, after being used two or three times, will show obvious differences in plant growth, crop quality, crop yield and disease resistance, and the more times water-soluble fertilizer is used, the greater the difference becomes.
Liquid water-soluble fertilizer
According to industry standards, the current market broadly has six kinds of liquid fertilizers: amino acid, humic acid, trace element, secondary element, macro element and organic water-soluble fertilizer. Although the types differ, distinguishing good quality from bad is much the same, mainly starting from the following aspects: one look, two weigh, three smell, four freeze, five test.
1. One look: look at the product's physical state. Good liquid fertilizer products are clear and transparent, clean and free of impurities, while although black solutions such as suspended fertilizers, amino acid and humic acid are not transparent, on careful observation a good product will have no sediment at the bottom of the bottle after being inverted, while a poor-quality product may have a lot of solid insoluble matter in the bottle.
2. Two weigh: weigh the product. According to industry standards, each product has a minimum nutrient content requirement. In liquid fertilizers, each nutrient element is measured in g/L, meaning the mass of nutrient element contained per unit volume. The larger the value, the heavier the same volume of liquid product, and the greater its specific gravity. Therefore, specific gravity is an important indicator for judging the quality of liquid fertilizer products. A good product does not necessarily have a very large specific gravity, but one with a very small specific gravity definitely does not have sufficient content. The specific gravity of qualified amino acid, humic acid and organic water-soluble liquid fertilizers is generally above 1.25, that is, 1 L of liquid fertilizer weighs more than 1.25 kg, and the specific gravity of macro, secondary and trace element liquid fertilizers is mostly above 1.35.
3. Three smell: smell the product's odor. Good products have no obvious odor, and some products have a slight ammonia smell under weakly acidic or weakly alkaline conditions. A strong ammonia smell means the pH was not controlled well; a special fragrance is generally to cover up certain odors; and a pungent odor is generally caused by adding substances that should not be added.
4. Four freeze: test the product's stability. Solid precipitation from a liquid fertilizer solution generally occurs in two situations: one is slow precipitation after long standing, and the other is precipitation at low temperature due to reduced solubility. Freezing is to test the product's stability under low-temperature conditions. A good product placed in a refrigerator for quick freezing for 24 hours will not separate or crystallize, while those products that separate and crystallize are caused by failure to select good raw materials and control the production process well.
5. Five test: this is not testing nutrient element content, but testing product properties as far as one is able. For example, use pH test paper to detect its acidity and alkalinity. High-content fluid fertilizer may be produced by ordinary manufacturers as strongly acidic or strongly alkaline, which is unsafe for crops, and it is very difficult to mix fluid fertilizer with other pesticides for application. Products made by manufacturers with strong technical expertise have a pH close to neutral or weakly acidic to weakly alkaline. Use monopotassium phosphate or monoammonium phosphate solution to test whether “sugar alcohol calcium” contains sugar alcohol. Products containing sugar alcohol have a high degree of calcium ion chelation, will not precipitate when encountering a phosphorus-containing solution, and are absorbed and transported quickly by crops. Use a low dilution factor to test product safety. Good liquid fertilizer products do not contain hormones and have a much lower electrical conductivity than powder formulations, so they are very safe even at a very low dilution factor and can be sprayed at a dilution of 100 times, 50 times or even lower.