RESPONSE OF BAMBARA GROUNDNUT (VIGNA SUBTERRANEA [L.] VERDC.) TO A SINGLE SUPER PHOSPHATE APPLICATION IN THE NORTHERN GUINEA SAVANNA OF NIGERIA

Abstract

The trial was conducted in the Institute of Agricultural Research (IAR) farm, located at Samaru, Nigeria, in two-year field trial (2019-2020) to identify the reaction and performance of Bambara groundnut landraces to single super phosphate (SSP) fertilization under Northern Guinea Savannah conditions. The experiment was tested on three landraces (Burkina, Nav-4, and Black) and three SSP rates (0, 45, and 90 kg P₂O₅ ha⁻¹) in a three-replication Randomized Complete Block Design. The findings demonstrated that 90 kg P₂O₅ ha⁻¹ had a significant positive effect in terms of nodulation, biomass production, pod yield, seed yield, shelling percentage and hundred-seed weight. Nav-4 landrace was confirmed as superior vegetative performance (plant height, canopy spread, leaf area index, and growth rate) with a maximum seed yield, shelling percentage, and biomass weight. The black landrace produced the largest number of pods and seeds. Correlation analysis showed that there was a strong positive correlation between seed yield and pod weight (r = 0.96), shelling percentage (r = 0.50-0.56), and biomass weight (r = 0.72). Path analysis found a pod weight as the key yield determinant, which explained 78-86% of the seed production variation. It was economically shown that the most profitable rates of net returns in 2020 were 90 kg P₂O₅ ha⁻¹: N315,468 (Burkina), N327,834 (Nav-4), N334,037 (Black). The study concludes that the use of SSP at 90 kg P₂O₅ ha⁻¹ in combination with Nav-4 landrace is the best option to achieve maximum Bambara groundnut production in Northern Guinea savannah of Nigeria.