Lionel...
To (try to) answer your original question - what do the instructions say? I would think you'd want a really tacky glue to hold the fibres in place. Are you trying to make bunched grasses, or a whole field?
If bunches, Harold has some good pointers, and you may also be able to use something like hot-melt glue that "dries" almost immediately.
For a whole field, I think that Harold's how-to on using faux fur is great. You can also look into the static applicators, but you are still left with the question of how to fix the grass before it falls over... I have used Elmers (and 3M) spray adhesives, and they are quick to dry. I don't know if they'd provide enough hold, but it's worth a try. And don't forget to take pictures for us!
Andrew