A study was conducted in 1990 and 1991 to evaluate root development and water use by cotton as affected by in-row subsoiling and the placement of K fertilizer. Measurements were taken from an ongoing field experiment established in 1989 to evaluate cotton response to the deep placement of K fertilizer. The experiment was located in central Alabama on a Norfolk fine sandy loam. For this study, 5 treatments were compared: 1) check without subsoiling, 2) check with in-row subsoiling, 3) 90 lb K₂O A^-1 surface applied without in-row subsoiling, 4) 90 lb K₂O A^-1 surface appied with in-row subsoiling, and 5) 90 lb K₂O A^-1 deep placed, in-row. Penetromenter readings taken in 1991 showed the soil has a well developed traffic pan at a depth of approximately 6-15 inches. The readings also show that in-row subsoiling disrupted the pan up to 10 inches away from the in-row position. Soil water and root density measurements taken in-row showed that water uptake and root growth at depths >8 inches were improved by subsoiling and the application of K fertilizer. Water depletion and root density at depths > 8 inches were generally greater for the treatment reciving the deep applied K. However, the application of K on the surface in combination with inrow subsoiling resulted in the highest whole plant weight, leaf surface area and seed cotton yield. Higher yields for the surface application of K with in-row subsoiling probably resulted since the surface applied K was exposed to a larger proportion of the cotton root system as compared to the in-row, deep placed K.