When someone starts growing plants one of the first things to consider is which form of fertilizer they want to use, powdered or liquid. Both have their advantages and disadvantages, we'll go through each and hopefully you can make an informed decision on which is the better option for your particular situation.
When a package of potato chips or cereal is nearly finished there will be all of the crumbs on the bottom. The nature of powders is that large particles wind up a the top and smaller one go to the bottom. No matter how good the blending technology is, there will always be a small degree of particle separation. However for the most part it shouldn't be anything to lose sleep over.
When ingredients are dissolved in water they disperse equally throughout the whole solution and in theory should be 100% consistent.
Using a liquid means that there will be extra shipping costs for the water which the fertilizer is dissolved in. On the other hand it is easier to package liquids which can drive down the production costs. Ultimately though, powders are probably the better bang for the buck.
Liquids win this hands down, measuring a volume and then diluting it into a larger volume is very easy whereas measuring a powder and then dissolving it for the dilution is way more work. Especially when it comes to using powder in cold water.
There was a time when precise digital scales were very expensive and therefore uncommon. These days they're affordable and not hard to find. If someone wants to grow using a powdered fertilizer a proper scale is essential, while there are usually directions in spoons its really hard to judge the measurement a lot of the time.
It should be extremely easy to find something to accurately measure volumes, even to the milliliter (a syringe has to be accurate for giving proper dosages to patients). For larger volumes a simple measuring cup from the dollar store is all that is needed.
In the end, this is all about the situation of the grower. If the powder can be properly weighed using a scale then it is every bit as good as measuring liquids.
For a chemical to undergo a reaction it usually has to be in an aqueous solution. This means that a the chances of a liquid fertilizer has a much greater likelihood of going bad over time. This can involve the ingredients reacting with each other, evaporation of the liquid, microbial growth, and oxidation. A rule of thumb is that all liquid fertilizers should be used within 2 years of purchase.
On the other hand it's much harder for powders to undergo any kind of degradation. If they are stored in a cool, dark, and dry place they should keep pretty much indefinitely, but will likely form clumps after a certain point.
This isn't an issue for everyone but can be a concern for some. It can take a fair bit of strength to carry around properly use a 20 liter jug of fertilizer. There are also situations where people are carrying nutrients off the beaten path so that they can maintain their privacy. If weight has a bearing then powders would have the edge in this category.
The author can not recommend one type of fertilizer over the other since the circumstances of every garden will be a little different and so ultimately it must be the decision of the grower on what type of system they want to use. Hopefully this has provided a few points that you haven't considered when making that decision.