Yard Butler D-6C Lawn Coring Aerator ToolLawns where a lot of activity takes place can become compacted. Over time thatch can also build up to create a barrier, keeping water and air from reaching the roots. Core aeration reduces compaction and thatch to let air, water, and fertilizer down to the root zone. Healthy roots are essential to good lawn growth. Core aeration also stimulates root growth by pruning the roots. As an added benefit, the removed cores deposit valuable micro organisms on