Evaluation of Calcium Fertilization in Irrigated and Non-Irrigated Runner Peanut.

Insufficient Ca availability can reduce peanut (Arachis hypogaea L.) yield. Lime (CaCO₃) and gypsum (CaSO₄) are the primary sources for Ca fertilization in peanut. This study was conducted to determine whether lime, gypsum, or a combination is more productive under irrigated or non-irrigated conditions. Peanut was grown in 2016 on a Tifton loamy sand (Fine-loamy, kaolinitic, thermic Plinthic Kandiudults) in Tifton, GA. Irrigated and non-irrigated blocks (main-plot effect) with four treatments of Ca sources in each block (sub-plot effect) were applied in a split plot design with eight replications. The treatments in each irrigated and non-irrigated block included: lime (448 kg Ca ha^-1) at the time of planting, gypsum (224 kg Ca ha^-1) at first bloom (approximately 35 days after planting), lime (448 kg Ca ha^-1) at planting plus gypsum (224 kg Ca ha^-1) at first bloom, and a non-treated check that received no supplemental Ca. Typical soil test Ca was initially in the range of 251-513 kg Ca ha^-1 in the pegging zone (top 8 cm of soil) at planting. Based on the 2016 study, irrigation was significant for yield (p<0.0001). Irrigated peanut (6760 kg ha^-1) yielded more than non-irrigated peanut (5050 kg ha^-1) averaged over Ca treatments. There was no significance between Ca treatments (p>0.10) and no interaction between irrigation and Ca treatment effects (p>0.10). Irrigation is an important tool for maximizing peanut yield. More research is needed related to original soil test Ca levels and timing of fertilization and irrigation treatments to determine when Ca application can be most critical for improving peanut production.