I DON’T UNDERSTAND WHAT THE NUMBERS (FORMULA) ON THE FERTILIZER’S PACKAGE MEAN?
The numbers (or fertilizer formula) on the package are the percentages of nutrients present in each specific fertilizer (concentrations of elements guaranteed by the manufacturer of these fertilizers). Most often, three fertilizers are indicated on each of the fertilizers (through a hyphen or a colon): the first is the nitrogen content (N), the second is the phosphorus content (as P2O5), and the third is the potassium content (as K2O). These elements are considered essential nutrients and are called macronutrients, because the needs of plants in these three elements are much higher than in other essential nutrients. For example, if the first number (nitrogen content) in the package is 25%, it means that 100 kg of fertilizer contains 25 kg of nitrogen. Also in addition to nitrogen, phosphorus and potassium, fertilizers may contain other nutrients such as sulfur, magnesium or trace elements.