A spike aerator creates holes in the ground by pushing the soil sideways as wedge-shaped spikes penetrate the soil. Since there is no soil removed from the ground, watering will cause the compacted soil around the holes to expand and close. A core/plug aerator removes soil from the ground and leaves the core on the turf. This reduces compaction in the soil, and the holes can stay open for a long time allowing air, fertilisers, and water to reach the roots. Core aeration is suitable for heavy clay soils, and spike aeration is more suited to sandy or loamy soils.