Western soils are typically high in plant available potassium. However, observations by New Mexico cotton producers indicate enhanced fiber quality when potash is broadcast prior to planting cotton despite high levels of soil potassium. A five-year study (1991-1995) was conducted at the NMSU Agricultural Science Center to evaluate additional potassium fertilizer for cotton yield and fiber quality enhancement given a high soil test potassium level. Five replications of a zero control, 50 lb/A and 100 lb/A of 0-0-60 were applied to a long-term (30-year) Acala 1517 production field. There were significant yield (r=0.0001) and quality (r=0.0002) differences among years of production but no effects were observed due to additional potassium fertilizer. When soil testing reveals high levels of plant available potassium the likelihood of a response or an economic return is essentially zero. However, on-farm soil test potassium levels evaluated for spatial variability in 1998 indicate that some fields can be classified as low to medium in plant available potassium. Under these conditions it is more likely that there may be a response to additional potassium for New Mexico cotton production.