Long‐Term Liming Effects on Coastal Plain Soils and Crops

Abstract

Most soils in the southern Coastal Plain need liming; however, long‐term data are needed on its value and changes in soil profile pH, Ca, or Mg. Field studies with lime rates have been maintained on a Tifton soil (Plinthic Kandiudult) for 31 yr and on Pelham soil (Arenic Paleaquult) for 24 yr to determine soil chemical changes, rates needed for high yields, and if yield of cotton (Gossypium hirsutum L.) on low‐pH soils can be increased by Ca or Mg fertilization. Total amounts [calcium carbonate (CaCO3) equivalent] of dolomitic lime were 0, 7.5, 15.0, and 30.0 Mg ha−1 for Tifton and 0, 11.7, and 34.0 Mg ha−1 for the Pelham. Liming increased pH, Ca, and Mg to a depth of 90 cm. Decreases in pH, Ca, and Mg were closely related to the amount of ammoniacal N (NH4–N) applied. Application of 15 Mg ha−1 dolomitic lime on the Tifton soil for 31 yr and 34 Mg ha−1 on the Pelham soil for 24 yr maintained surface soil (0–15 cm) pH near 6.0 and provided greatest crop yield. In no‐lime plots, in 2000, exchangeable Al (0–45 cm depth) was >0.3 cmolc kg−1, and Al saturation was >15% of the effective cation exchange capacity on Tifton soil and >20% on Pelham soil. In those plots, low cotton yields were not increased by fertilization with Ca or Mg salts without liming. Providing 5.25 and 14 kg lime kg−1 N for the Tifton and Pelham soils, respectively, decreased soil Al saturation to <7%.