LEAVES -- WHAT CAN YOU DO?
Mulch Them In Place/Mow Them
Leaves are rich in carbon, phosphorus, and potassium - all essential nutrients needed by plants including turf grasses (Wisconsin Department of Natural Resources). Simply mow your leaves along with the grass during fall, and let the small leaf pieces filter down among the grass blades. Make sure grass is exposed to the sun after the tree leaves have been mulched.
The following guidance is taken from the Department of Horticulture - Michigan State University Green Tips sheet on Mulching Tree Leaves Into Lawns.
Although additional nitrogen has not shown any major benefit, the Department of Horticulture - Michigan State University suggests applying 1/2 pound of nitrogen per 1,000 square feet in addition to the normal fall fertilization in order to speed tree leaf decomposition