Sodium Bentonite clay available in...
Noweed is a woven polypropylene fabric made for weed control in nurseries, landscaping and horticulture. Helps stop weeds while allowing flow of nutrients and air.
Noweed is manufactured with a very tight weave but has micro perforations to allow water and nutrients to flow through the fabric. If you examine Noweed against most weed control fabrics you'll see that the others are of a wider weave plus they are not micro perforated to allow nutrients to flow through. Those type of fabrics will sour the soil.
Preparation of soil is recommended prior to installation. In particular certain grasses such as couch should entirely eradicated by means of steaming.