Healthy soil is more than the nutrient and pH read out from your soil test. It is also the ecosystem of bugs, bacteria and fungi living just under the surface. Applying organic compost to your lawn helps keep the cycle of life thriving in your soil. As the compost seeps into your soil, critical micronutrients will be absorbed by the roots leading to greener blades and a more disease resistant plant.
I recommend top dressing in the fall to give your spring lawn a head start.