Abstract
Research efforts to examine groundnut (Arachis hypogaea L.) response to fertilizer have been frustrated by the erratic nature of responses to individual nutrients. An experiment was established on acid sandy soil to determine the effects of Ca, Mg, and K on groundnut yield, nutrient uptake, and soil chemical properties. Field experiments were laid out in a 3 x 3 x 2 factorial structure in a randomized complete block design with three replicates. A greenhouse experiment was laid out in a 3 x 3 x 3 factorial combination of Ca, Mg, and K. In the field experiment, 3 rates of Ca and Mg, and 2 of K were combined factorially to give 18 treatments. The nutrient rates were: 0, 160, and 320 kg Ca ha-1; 0, 9, and 18 kg Mg ha-1; and 0 and 50 kg K ha-1. Calcium significantly increased groundnut kernel yield, but decreased dry matter production. Negative interaction of Ca and K resulted in suppressed uptake of K. Soil Ca, Mg, and pH levels increased following application of calcitic lime (40% Ca, 4.5% Mg).
