Soil improvement for heavy soil / clay to creat very good drainage?

floor aquaponics systems: question bibi : soil improvement for heavy soil / clay to creat good drainage I foresee something like pepper AC / oleader tree and flowers on the area that seems to have really poor drainage and heavy soils in the strategy. I have to pass a test by digging a 6 "deep hole and fill it with water, the water there are more than 1 1 / 2 hours. I heard that good drainage is extremely essential for most plants. What can I do to boost drainage or altering heavy soils? I

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