Question: how does gypsum break down clay?
Answer: The first step is to add gypsum to the soil. Apply gypsum at 1 kilo per square metre, digging this into the top 10-15cm well. Gypsum works on the clay, breaking it up into small crumbly pieces making it easier to work with and also improves drainage. ... The next step is to build up the soil with plenty of organic matter.