Complex sentence: Plows or harrows may be used to periodically break up vegetation mats slowing surface disposal; and subsurface disposal typically uses pipes placed deep enough to minimize root penetration and often manages overlying vegetation to avoid growth of plants with deep root systems.
Split into simpler sentences: Plows or harrows may be used to periodically break up vegetation mats which are slowing surface disposal. Subsurface disposal typically uses pipes placed deep enough to minimize root penetration and often manages overlying vegetation to avoid growth of plants with deep root systems.