Effects of Applied Gypsum on Soil and Seed Calcium and Peanut Quality.

Past studies of peanut (Arachis hypogaea) demonstrate that calcium in the pegging/fruiting zone is essential for proper seed development. For soils low in calcium, gypsum is recommended at 600 kg/ha for general production and 1200 kg/ha for seed production. Actual relationships between soil and seed calcium on seed quality are largely unknown, especially for newer larger-seeded peanut varieties. The objective is to determine the effects of gypsum applications to the pegging zone on peanut seeds from large- and medium-seeded peanut cultivars (i.e., 06G and Georgia Green, respectively). Gypsum was applied at 0, 600, and 1200 kg/ha to low calcium soils. Three replicates of each cultivar and calcium treatment were established in Headland, AL with irrigation and Tifton, GA without irrigation in a randomized complete block design. Soil samples from the pegging zone and representative peanut samples were collected weekly. Soil and peanut samples were analyzed for Ca, Mg, and K. Moisture content and soil temperature were monitored every 30 min during peanut development. Once harvested, the yield, grade, germination, and vigor test were determined. Results from the first season show that higher calcium in non-irrigated plots improved grade and price per tonne of both cultivars. In irrigated plots, yield of Georgia Green decreased in the highest calcium treatment. Other non-statistically significant observations include an increase in 06G yields in non-irrigated plots and increasing price per tonne in irrigated plots with increasing calcium treatment. Seed calcium increased with increasing calcium amendment for both cultivars. Mean seed calcium concentrations were 250 ± 84, 334 ± 102, 404 ± 104 mg/kg for Tifton and 248 ± 71, 403 ± 86, and 489 ± 102 mg/kg for Headland. Other variables such as soil moisture and temperature; soil Ca, Mg, and K levels; and peanut germination and vigor results will also be discussed.