
Certified GKH Gardening Expert
There aren't many ways to kill this off without harming the soil in any way. The least harmful method would have to be pouring boiling water over the grass. This will kill them on contact, while leaving the soil alone, except for killing what it touches at that moment. After this, your native grass will take back over. Just keep applying until there are no more shoots that come up, as they can spread seeds that may lay dormant for awhile. It will just take a little time to kill this off completely.
Alternatively, if you want to get rid of it in one go with a selective herbicide, then you can choose one specifically for this weed. It will not harm other grasses, but there will be residual chemicals left over.