1.Make a symmetrical lattice, go into the terrain editor, set the mesh density to the lowest or second lowest resolution, and draw a nice grass blade, maybe a very slightly curved line, make sure it is a shape good for a side-on profile of your grass blade, get out of there, flatten out your lattice nice and thin, and rotate it until its the right way round. 2.Make your material for your blade now. 3.Duplicate this lattice until you have a clump of grass. 4.Now rotate and position these individual blades around till this grass patch has a slightly random/natural character. 5.Bear with me, because this technique looks really good if done correctly. 6.group and then multireplicate or hand duplicate this group. 7.make sure you tweak the rotation,size,density and position of your duplicate groups every so often to induce a more random/natural appearance. 8.Do the step above until you feel you have enough grass, position your groups or groups of groups from the top view, until they cover the areas you want covered. 9.ungroup all the grass groups go to the align icon, open its little menu, press snap to ground. 10. Group all the grass lattices and move the group up until it is above ALL the terrains it has to cover.(You must only have the terrains that you want covered in grass in your scene until you finish doing all these steps.) 11.Make sure all the lattices are just above the highest points of all your terrains, ungroup the lattice group, go to the align menu, press "SNAP TO LAND". 12.Try this technique, render...it is worth the effort, but make sure your blade shape and material are just right from the start...