Question Transparency shader need Help!!!!

Hello every one,i m making my own tilebase game with my own terrain system(so easy just procedurely generate mesh and set uv to ruled merge),and now i have a very big problem with the transparency shader,please have a look at the picture,I have a grass tile and a sand tile,now I want the effect like the picture in red box that the edge of sand tile is transparency.but this will bring the transparency render problem that if i use alpha blend(turn off z-write),then i cannot control the grass/sand tile's sort order,or if I turn on z-write,then there will show strange when any other transparency cover,,,and I know this is up to the gpu workflow,but I still want to know is there any way to solve this, btw in my game I have height,so cannot set ground tile's sort layer or sort order to solve.