Relating the Fertility Capability Classification System to Tobacco Response to Potassium Fertilization

Abstract

AbstractThe Fertility Capability Classification (FCC) system is a technical soil classification system developed to evaluate soil properties affecting crop response to fertilization and to aid in making fertilizer recommendations. It was developed primarily for use in lesser developed countries. Results from a series of experiments involving application of K to flue‐cured tobacco (Nicotiana tabacum L.) in North Carolina were used to determine the usefulness of the FCC system for predicting crop response to fertilization in the southeastern USA. Six rates of K, ranging from 0 to 224 kg ha−1, were applied to flue‐cured tobacco at 13 locations for 3 yr. Tobacco leaf yield response to K differed significantly among FCC soil groups. Optimum rates by soil group varied from 0 to 112 kg ha−1, compared with 84 kg ha−1 across all soils. The highest optimum rates occurred on soils with sand or loamy sand surfaces >0.5 m thick, whereas the lowest rates were on soils with loamy surfaces. Extractable soil K level in the Ap horizon (soil test K) was not related to response to K, either overall or within FCC groups. The FCC system was useful in evaluating tobacco leaf yield response to fertilization. It appears that the FCC system could be used to improve fertilizer recommendations.