Performance and Dry Matter Accumulation of Groundnut in an Ultisol Amended with Phosphorus and Lime.

<b>Background and Objective:</b> Adequate yield improvement in groundnut may not be achieved in acid sand Ultisol through the application of mineral phosphorus alone, however, a combined application of lime and phosphorus fertilizer may be a better management option in such soils. Hence, this study evaluated the effects of four levels of lime (0, 2.0, 4.0 and 8.0 t ha¹) and four phosphorus (P) levels (0, 25, 50 and 75 kg ha¹) on the performance of groundnut (<i>Arachis hypogaea </i>L.) in the humid rainforest of South Eastern Nigeria. <b>Materials and Methods:</b> The study was a factorial experiment laid out in a Randomized Complete Block Design (RCBD) and consisted of sixteen treatment combinations replicated three times each. <b>Results:</b> The result obtained showed that the application of phosphorus fertilizer and lime had a significant (p<0.05) effect on plant height, number of leaves per plant, number of branches per plant, 75 kg ha¹ P and 8.0 t ha¹ lime resulted in the highest growth parameter. Similarly, 75 kg ha¹ P and 8.0 t ha¹ lime significantly improved the number of pods per plant 30.67, pod yield 3.58 t ha¹, biomass yield of 4.68 t ha¹, seed yield of 2.1 t ha¹ and 100 seed weight of 44.58 g, seed yield of groundnut while curtailing the number of unfilled pods 2.33. <b>Conclusion:</b> Application of phosphorus and lime at 75 kg ha¹ P and 8.0 t ha¹ lime is a beneficial agronomic practice that could enhance the productivity of groundnut in the Calabar rainforest zone of Cross River State.