It produces high Alkaline conditions and this locks up available nutrients so that they are not accessible to plants or turf. This in effect means your turf will not grow well. In fact it may not grow at all. To demonstrate these conditions, we pH tested the underlay.
Here is an example. The before and after photos showing just 12weeks. This turf was laid on top of this bad underlay.
Please Remember Always use a good base and topsoil to prep the site before you lay your turf.