In-Row Subsoiling and Potassium Placement Effects on Root Growth and Potassium Content of Cotton
Mullins, Gregory L. | Reeves, Donald W. | Burmester, Charles H. | Bryant, Hamilton H.
One method of correcting K deficiencies in cotton (Gossypium hirsutum L.) is by in-row deep placement of K fertilizer. At present, the mechanisms involved in cotton yield response to deep placement of K have not been elucidated.A field study was conducted in 1990 and 1991 to evaluate root development and dry matter yield of cotton as affected by in-row subsoiling and placement of K fertilizer. The experiment was located in central Alabama on a Norfolk fine sandy loam (fine-loamy, siliceous, thermic Typic Kandiudult). Five treatments were compared: (i) check, without in-row subsoiling; (ii) check, with in-row subsoiling; (iii) 84 kg K ha⁻¹ surface-applied, without in-row subsoiling; (iv) 84 kg K ha⁻ surface-applied, with in-row subsoiling; and (v) 84 kg K ha⁻ deep-placed, in-row. Penetrometer readings taken in 1991 demonstrated that the soil has a well-developed traffic pan at a depth of approximately 15 to 38 cm. In-row subsoiling disrupted the pan up to 25 cm away from the in-row position. Root density measurements taken in-row showed that root growth at depths > 20 cm was improved by in-row subsoiling and K fertilization. Cotton root growth at depths > 20 cm was generally better for the treatment receiving the deep applied K. However, broadcast K in combination with in-row subsoiling resulted in the highest productivity and K accumulation per plant. Results of this study suggest that, for cotton production in Alabama, deep placement of K is not superior to broadcast applications of K. Contribution of Auburn Univ. Dep. of Agronomy and Soils and the Alabama Agric. Exp. Stn. Journal Series no. 3-923323.
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