How can I break a minecart with the environment without destroying it?

This has been solved by some smart redstone YouTubers, with one of their tutorial videos below:

They drop the cart next to a cactus, but in my testing, I haven't found this to be strictly necessary. Simply having the cart travel straight into a cactus also works. The key in both instances is to have a hopper ready to accept the itemized cart. Without it, there's a chance it'll be destroyed by the cactus. The design below shows this, and is inspired by BDoubleO100 in this video. It may be hard to see, but there is track on top of a hopper which feeds the dispenser. The slab above serves 2 purposes: prevent the cactus from growing, and prevent damage to a hapless player, should they enter the area by mistake.