worms
Your garden soil needs the ordinary worms , not the tigers,as you already found out.If you have some time than they will appear by them self.Work in plenty of organic matter and cover with compost or leaves.If you want to enhance the settlement of the willing helpers you can catch them after dusk with a weak torch .In the night (when the birds sleep)they come out of the soil to mate.You have to walk very quired like a heron and pick them very quick and resolute,otherwise they retreat in the fraction of a second back into the soil .
Don't pick to many in one spot. The best nights are damp and warm and don't keep them in the bucket for long,certainly not for a day.
There is also a method to catch them electrically but I won't tell for ethical reasons.And it is dangerous too.
Once your garden is back on recovery don't use weed killers,pesticides and synthetically fertilizer,these would drive them away again.