Do you have a problem lawn that no one has been able to fix? Many lawn care services will simply throw more fertilizer at a problem hoping it will go away. This could be a short term fix, but make the situation worse in the long run.
Soils can vary greatly from home to home, even in the same neighbourhood. Nutrient levels can become depleted or imbalanced over time due to over or under fertilizing, the use of irrigation systems or major changes in the landscape. Quite often, acidity levels (pH) can be too high (alkaline) or too low (acidic) which will affect the ability of your turf to absorb nutrients from both fertilizers and the soil.