My favourite solution so far was to use plants that turn red near mines, thus pretty much creating red circles around their location. I read about it few years ago in a science magazine, but somehow the research seems to have died.
Unfortunately Aresa Biodetection, the company behind that, stopped all research into their strain of the thale cress plant for landmine detection. I would guess that they hit a dead-end in their research, perhaps they could not make it reliable enough.
Judging by the video, growing anything on that land would be near impossible - it may be that this is often an issue?
Maybe they couldn't find a farmer brave enough to seed a minefield?
And how do you irrigate and fertilize mined territory in the Afghan desert in a way that's cheaper than actual demining? Walking around with a hose or setting up an irrigation system seems too dangerous (or require partial demining to create footpaths anyway), and using any type of aircraft is expensive.
Cactus? The American southwest is largely desert, but there are plants adapted to the low moisture environment.
There are already large numbers of aircraft flying over Afghanistan looking for the Taliban, aren't there? That's obviously not too expensive, it's just a question of political will.
Uhm... now we just need some other plants that turn desert sand to fertile soil.