Infinite Gameplay Terrain Question

hey,

i'm working on infinite gameplay.
for this i wanted/need to move my terrain dynamically.
but this is not working.

(nothing happend. the code works with every other asset, just not with terrain)

PHP:

var obj;

function Awake() {
    obj = gameObject.FindWithTag( "obj" );
}

function FixedUpdate () {
    
    if( obj ) {
        transform.position.x = obj.transform.position.x - 500;
    }
}



With a Plane this works fine!
Problem is the Standard Grass Texture does not look as nice on a Plane like on the Terrain.
(I don't need the rest of the features of a Terrain actually..)

Does somebody have an idea how to make this work?
(Or what I can do to make the Texture look better on a big plane?)

thx
cheers