Static grass usually requires a static applicator-- in short, it requires a static charge to apply it properly. Model Railroad companies like Walthers sell electric applicators, although Noch makes one that is a "rub" type- its made from a special vinyl plastic that you rub on a wool surface to give the static grass inside a charge, then shake it over the naturally charged terrain surface, but I've found this only works well in a really low humidity environment. Usually, modelers use a diluted form of white glue as the medium to make the "grass" adhere to the surface. With the electric applicator, dilluted white glue is applied, a wire on a nail is inserted and a charge is applied. The applicator then provides a charge to the static grass, which causes it to stand up when it hits the surface of the terrain. The Noch applicator skips this step. Usually, terrain builders apply sand or ground foam to a surface let it dry, then flow on Acrylic paints it in the appropriate colors. When that's dry you apply the diluted white glue, and apply the static grass while the glue is tacky. When diluting white glue, add a drop of dishwashing detergent-- it will improve the flow. I think there's a you-tube tutorial for building a static grass applicator-- it's not complicated if you want to build your own. Hope this helps.
VR, Russ