For terrible clay soils, there is a German gardening technique called Hügelkultur that also involves adding organic matter, but in much larger chunks that will

For terrible clay soils, there is a German gardening technique called Hügelkultur that also involves adding organic matter, but in much larger chunks that will slowly break down over time. The version that I've seen used in clay soil involves burying logs and split firewood in the clay and then building up a raised bed on top using finer and finer materials as you work your way up. https://www.farmersalmanac.com/what-hugelkultur https://www.farmersalmanac.com/what-hugelkultur