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Sweet Potato Response to K and P Fertilization
- Nicholaides, J. J., Chancy, H. F., Mascagni, H. J., Wilson, L. G., Eaddy, D. W.
- Agronomy journal 1985 v.77 no.3 pp. 466-470
- coastal plains, Ipomoea batatas, phosphorus fertilizers, potassium fertilizers, North Carolina
- Limited literature is available to provide recommendations of K source and rate and P rate for sweet potato [Ipomoea batatas (L.) Lam.] production. Many growers, therefore, continue to use the more expensive sulfate (SO₄) source of K rather than chloride (Cl) and higher than recommended rates of K and P. Accordingly, on-farm experiments were conducted during 3 years on North Carolina Paleudults to determine effects of K source and rate and Prate on sweet potato yield, grade, and quality. Potassium sources were KCl and K₂S0₄. Fertilization rates of K varied over the five K experiments and depended on initial soil test levels which ranged from 0.04 to 0.12 cmol K L⁻¹ by Mehlich-I extractant. In the three P experiments, the various P rates were also dependent upon the initial soil test levels which ranged from 11 to 30 mg P L⁻¹ also by Mehlich-I extractant. As K source had no effect on yield, grade, or quality, it was concluded that the higher Cl concentrations, up to 22.8 g kg⁻¹, in vegetative tissue with increasing KCl rates had no detrimental effect on sweet potato yield, grade, or quality. Total yield response to K applications was obtained where soil test K levels were ≤ 0.08 cmol L⁻¹, although no. 1 yields increased only where soil test K levels were ≤ 0.05 cmol L⁻¹. Phosphorus applications had no effect on yield, grade, or quality of sweet potato.