Salt accumulations in soil in irrigated cotton production are a major issue in the arid and semiarid regions of western USA.  In many years, this leads to premature leaf drop between peak bloom and open boll.  The necrosis on the cotton leaf margins prior to senescence is often identified as potassium deficiency.  This is despite high soil test potassium levels.  We present cotton leaf potassium and salts data from farmer's fields in arid Pecos county to small plot studies in semiardid Lubbock county.  We observed that in wet years when soil salts are less of an issue, leaf K is high and leaf Ca is low.  In drier years in Lubbock and when leaves drop prematurely in all areas, leaf K is low and leaf Ca is high.