Grass can only use so much of each element. That maximum amount the grass can use is a function of two things: how much the grass grows and the concentration of the element within the grass plant. From those basic principles, we can determine the minimum amount of an element that must be supplied to the plant. That is, the minimum amount to supply must be enough to meet the grass requirements. Applying more of an element than the grass can use will probably not produce any turf response.
The minimum levels for sustainable nutrition (MLSN) guidelines, as explained in the article, ensure that the nutrients supplied from the soil and by fertilizer applications are enough to meet the grass requirements. And by making some simple calculations to estimate grass use of each element, while accounting for the quantity of available nutrients in the soil, the MLSN guidelines reduce the risk of excessive nutrient applications.