The answer to 'why is my lawn erosion' is that lawn erosion is typically caused by heavy rain, water runoff, or poor soil drainage. Symptoms include bare patches, gullies, and soil being washed away. Solutions include improving drainage, planting groundcover, and using erosion control methods like terracing or retaining walls.
For minor erosion, homeowners can often fix the problem themselves with DIY techniques. But for severe or recurring erosion, it's best to call in a professional landscaper who can assess the root causes and implement a long-term solution to stabilize your lawn.