Cotton continues to be one of the major row crops in Mississippi Delta Region of Arkansas. Nitrogen and K fertilization of cotton in Arkansas is based on preplant soil test NO₃-N and K levels and petiole NO₃-N and K concentrations between first bloom and boll opening. This diagnostic approach is based on field research in late 70's and early 80's and enabled many Arkansas and other mid-south growers to produce high cotton yields for many years. However, cotton production practices have dramatically changed during the past two decades.