One of the best ways to prevent erosion on a hillside is to install a ground cover such as grass. Grass roots will dig into the soil and anchor soil particles to prevent them from washing away. The fastest method to prevent erosion is to lay sod rather than planting seeds, sprigging or plugging. Sod provides an instant cover to anchor soil while the roots become established.
Test the soil on the hillside by digging 1 quart from 10 different locations on the hillside. Mix the soil in a bucket and allow it to dry. Pick out rocks, sticks and debris such as weeds and roots. Fill a sandwich bag with 1 cup of soil and take it for testing at a soil laboratory to determine the pH of the soil and the soil's structure.
Break up the soil on the hillside to a depth of 12 inches with a rototiller. Pass the rototiller over the soil in contours that run parallel to the shape of the hillside to prevent erosion.
Spread soil amendments over the soil to a depth of 4 inches based on the recommendations from the soil test. Common amendments include organic materials such as compost and peat moss. Organic amendments will help aerate clay soil and help sandy soil retain moisture. You can also add lime to raise the pH of your soil or sulfur to lower it.
Smooth out the soil using a landscaping rake.
Water the soil until it is slightly damp to facilitate putting down sod. Be careful not to water so heavily that water will run off and carry soil away with it.
Place sod in staggered strips over the hillside. Sod should be placed on the hillside within 24 hours of purchase to ensure the grass remains alive.
Roll over the sod with a sod roller to force the roots into contact with the soil.
Water the sod with 1/4 inch of water up to four times daily for up to 10 days to keep the sod moist until the roots of the grass become established. Gradually decrease the water until you are only watering with 1 inch every 10 days.