We’ve broken up an old tarmac tennis court but wonder if we can plant on top of the broken pieces ( once top soil has been added ). Will the underlying tarmac kill any plants?
But it would be best to scrape away the broken tarmac, even is some of the hardcore base is mixed in. A digger could lift and load that in a short time. There would be costs involved, of course, even for dumping, unless you could find somebody who wanted some hard fill material.
If you are trying to avoid cost, you could plant trees over the area at about 2 metres centres, though at random spacing. You can only use plants that need no more cultivating as the soil filled with tarmac will make this impossible, but you could plant trees, using small transplants and making some access for them through the tarmac and base, adding some good soil.