Soil Layering

A distinct layer within a soil profile which can affect the rate of water infiltration, percolation, rooting depth and air-filled porosity. A typical example of how this can arise is where different soil types have been applied as top-dressings. This can result in distinct layers being formed, especially if the turf surface had not been prepared properly beforehand prior to the top-dressing being applied. A sandy soil overlying a loamy, or heavier, soil can also produce soil layering, often resulting in plant roots being restricted to the sandier surface layer. This is due to a discontinuity in water penetration resulting from the difference in the soil textures where they meet.

Other causes of soil layering include:
• Top-dressings that haven’t been well worked into the surface.
• Excessive top-dressing being applied which effectively smothers the turf surface.
• Applying a top-dressing over a thatch layer, especially where no preparation work, such as hollow-tining, has been carried out beforehand.
• Distinct layering can also occur where the depth of aeration is consistent and not being varied. This results in roots only penetrating to the aeration depth often producing a topsoil layer which might have a reasonable, relatively darker coloured, soil structure but which has a root break at its base and a noticeable soil pan with a compacted surface developing beneath the roots.