Dear SAM, I have a low area in my pasture where a tall, coarse bunch grass is growing. My horses won't eat it. I'm thinking of replanting the low area with something the horses like better.
Plants grow in environments that favor their presence.
A low area may be high in salts or have a high water table. If that is the case, planting a grass that cannot tolerate salinity or wet soils will not be successful. A soil test will tell you if salinity is a problem. I am guessing your undesirable grass might be tall wheatgrass. Tall wheatgrass is more tolerant of salinity than many other species.