Subsoil potassium deficiencies that affect cotton yields have previously been identified in the Mississippi Delta. This paper presents the results from the first two years of a planned four-year study concerning nitrogen and potassium rates applied in split applications and their effect on lint yield of DES 119 grown an potassium deficient soils with adequate limestone levels.

Correcting subsoil potassium deficiencies by deep band placement in the drill behind a parabolic super chisel shank was explored in this and other studies. Three nitrogen rates (90, 120, and 150 lb N/A) and four potassium rates (0, 60, 120, and 180 lb K₂O/A) were applied in split applications to study their effect on lint yield of DES 119 cotton.

Potassium applied in split applications (60, 120, and 180 lb K₂O/A) increased (P<.05) lint yields when compared to the check (no potassium) treatment at all three nitrogen levels. Every 60 lb K₂O/A increment increase in potassium (0 to 180 lb K₂O/A) produced significantly higher lint yields in this study. Earliness (% first harvest) was not changed significantly by applications of potassium even though the first pick lint yields were increased at each successive potash addition. Overall, treatments receiving the 150 lb N/A tended to produce the highest lint yields.