The rather heavy textured soils that dominate the Texas Blacklands have traditionally been thought to contain adequate K for the production of most crops. However, reports of symptoms resembling K deficiency in cotton are becoming more common in the region. Furthermore, the occurrence and severity of Alternaria leaf spot on cotton has increased in the past several years. Research in other areas has shown that inadequate K nutrition may be associated with the occurrence of Alternaria. The objectives of this study are to determine the effect of soil and foliar applied K fertilizer on cotton lint yield and quality at various row spacings.