Abstract
Sandy soils of the southern coastal plain are commonly deficient in Ca in the upper 8 cm; this limits development of high yielding and high quality peanut (Arachis hypogaea L.). Calcium is often leached by rainfall and irrigation from such soils and is not available for the development of pods. Previous studies have shown that gypsum applied at bloom is effective for supplying Ca and increasing yield and grade when Mehlich 1 soil Ca in less than 200 to 250 mg kg-1 for runner-type peanut, and is nearly always effective for virginia-type peanut. Field experiments were conducted over 3 years to compare preplant incorporated limestone and gypsum application at bloom for both runner- and virginia-types. Preplant incorporated limestone was effective for reducing pod rot and for increasing pod yield, SMK, and value ha-1 for runner peanut in experiments conducted on sandy soils with pH less than 6.2 and with Mehlich 1 extractable Ca less than 200 mg kg-1. Application of Ca was not effective when extractable Ca was greater than 200 mg kg-1. Calcitic and dolomitic limestones were both effective for the runner-type. Limestone was also an effective source for virginia peanut. However, in our studies conducted on sands, the least pod rot and the greatest yield, grade, and value of virginia peanut were only attained when bloom gypsum was applied. Preplant incorporated gypsum was not as effective as bloom gypsum for either type of peanut.
1Contribution from the Departments of Crop and Soil Sciences and Plant Pathology, Coastal Plain Experiment Station and Cooperative Extension Service, Univ. of Georgia. This research was supported in part by funds from the Georgia Peanut Commission.
Author notes
2Professor, Assoc. Professor, former Research Associate, Professor, and Ag. Research Statistician, respectively.