The Mystery Numbers

What does NPK mean and what is an NPK ratio?  

NPK ratios, also known as grades, are a very loose guide or reference to the % of nitrogen, phosphorus and potassium contained within a fertilizer. U.S. State Agricultural departments require this info to be displayed on the fertilizer product label, however, only whole (integer) numbers are generally permitted and a fertilizer manufacturer must round down to a whole % number. 

For example, if a fertilizer has an actual 5.00% of N, as reported by a third party analytical laboratory, it must be stated as 4% on the label - here’s why.  The % of an element advertised on the product label is a guaranteed minimum, so a manufacturer needs to reduce the % guarantee on the label by approximately 3 - 5% to allow for manufacturing drift.  If an Ag inspector pulls a fertilizer product from the retail shelf and has it analyzed (and they always do) and finds that a chemical is lower than the minimum guaranteed % of the chemical as stated on the label, the manufacturer will be accosted and potentially fined. So this means that if a product had an actual 5% of N, the manufacturer would advertise 4.8% of N, however, because only whole numbers can be advertised, they must list the N as 4%. 

Therefore if one manufacturer has 5.00% N and another has 5.20% in their fertilizer, the N on their respective labels would be 4 vs 5, although they have pretty much the same amount of nitrogen in them! 

On top of this, water has a chemical saturation point based on the type of chemical given its max solubility AND temperature.  If you load water with chemicals to their maximum solubility at 75F, and then chilled or froze the water with the chemicals in it, some of the elements would crystallize and fallout.  Typically the elements will go back into solution upon heating the water, however it is not a preferred option as it can denature the solution and nobody wants to have submerge their nutrient bottles in buckets of hot water - which is especially difficult with 55 gal drums. 

Nutrient manufacturers like General Hydroponics include text on their labels, and I quote: 

“This product is concentrated to the limit of solubility.  Protect from freezing and direct sunlight.  If crystallization occurs, mix entire contents with an equal amount of hot water and double the amount used.” 

This is NOT something we would promote here at Dutch Master Nutrients!  Firstly it is a huge inconvenience to the customer.  Secondly, it also potentially exposes the fertilizer to bacterial infections, unbalanced elemental ratios, pH swings etc.  Too many unknown factors, especially when the crop you grow can be worth approximately $2,000+ a pound! 

Remembering that shipping fertilizers across the U.S. means the products are bound to experience cold/frozen conditions, especially in winter and heated freight is a very expensive add-on cost. 

Dutch Master, in conjunction with Fujifilm scientists, did exhaustive freeze/thaw tests, also testing EC/PPM and pH after thawing, to make sure our products can handle the extreme weather often experienced in shipping, and still be 100% perfect for use.  All test results were completely successful! 

The last issue I would also like to address is providing a balanced elemental ratio to your plants.  Dutch Master scientists designed the new Commercial Edition range of products to work synergistically together to provide exactly that - a complete and balanced fertilizer profile.  Many fertilizer manufacturers formulate their base nutrients to be reasonably balanced, but also offer additional additives that ultimately unbalance the elemental profiling when used together. 

When our scientists designed the formulas of ALL Commercial Edition products, they took all details into account, ensuring the elemental ratios in our base nutrients (Aqua Feed, Coir Feed & Media Feed) have been calculated to synergistically include use with Commercial Edition Sila-Guard, Cal-Mag, Trich-XL, Zone & Saturator to provide a balanced, high-purity, nutrient formulation for optimal plant health, growth and maximal flower production.  For example, because Sila-Guard not only brings in silicon, it also brings in 5% of K (potassium), our scientists calculated and balanced out the total amount of K when using Sila-Guard combined with our base nutrients.