Beltwide Summary on the Impact of Potassium Applications on Cotton Yield

The increased yield potential of new varieties, better management by growers, and eradication of the boll weevil have pushed cotton yields to 3+ bales/acre on a regular basis.  Such high yields put a substantial demand on the cotton root system’s ability to take-up sufficient potassium (K) and other nutrients.  As K demands have increased, deep profile soil sampling has indicated decreasing levels of plant available K in the soils of many production regions, including soils believed to previously have sufficient K levels. Banded applications of K should provide increased K uptake efficiency and meet the high uptake demand for K needed to optimize yield and fiber quality.  The objectives of the trials are:  1.  Determine the soil potassium levels in the surface horizon and at depth in several cotton production regions experience K deficiency symptoms; 2.  Evaluation the application methods and rates of K on cotton yield, quality, and return on investment.  Trials were conducted at 11 locations across the Cotton Belt, from the Southwest to the East Coast.  Soil samples were collected to a minimum of a two feet depth at each site.  Potassium was applied via broadcast incorporated (0-0-60) or injected (0-0-15) at six inches depth at rates of 0, 40, 80, 120, and 160 lb K2O/a.  DP 1321 B2RF was planted at each location.  Leaf samples were collected at FB+2 weeks and analyzed for K levels.  Late-season plant ratings and disease incidence data were collected.  Plots were harvested, ginned, and fiber sample analyses conducted at Cotton Incorporated.  A summary of these results will be presented.