Optimizing Fertilizer and Nutrient Management for Wheat (Triticum aestivum L.) Cultivation in Ghana

Introduction: Wheat production in Ghana is recent, and evidence-based fertilizer recommendations suitable for the semi-deciduous agroecological zone are limited. This study evaluated the effects of varying mineral fertilizer rates and their integration with organic amendments on wheat productivity, nutrient use efficiency, and soil fertility. Methods: Pot experiments were conducted at the CSIR-Crops Research Institute, Ghana, over two consecutive seasons using wheat (Triticum aestivum L., cv. Pride 999). In the first season, sole N-P₂O₅-K₂O fertilizer rates (100-50-50, 150-50-50, 200-50-50, and 90-60-60 kg ha⁻¹) were tested. In the second season, mineral fertilizer was integrated with fermented organic fertilizer (FOF) at 6 mg ha⁻¹ or compost at 9 mg ha⁻¹. Grain yield, growth parameters, partial factor productivity (PFP), and post-harvest soil fertility were assessed. Results: In season one, maximum grain yields of 3.35 and 3.37 mg ha⁻¹ were obtained at 200-50-50 and 150-50-50 kg ha⁻¹ N-P₂O₅-K₂O, respectively, significantly exceeding the control (2.16 mg ha⁻¹) and 90-60-60 kg ha⁻¹ (2.27 mg ha⁻¹). Wheat yield increased linearly with nitrogen up to 200 kg ha⁻¹, while optimal P₂O₅ and K₂O rates of approximately 30.5 kg ha⁻¹ each produced yields of 3.31-3.33 mg ha⁻¹. Partial factor productivity declined from 14.9 to 11.2 and 10.8 kg grain kg⁻¹ nutrient at 100-50-50, 200-50-50, and 90-60-60 kg ha⁻¹, respectively. In the second season, integrated fertilizer treatments averaged 3.14 mg ha⁻¹, outperforming average sole mineral fertilizer (2.81 mg ha⁻¹) in the first season. The highest yield (3.77 Mg ha⁻¹) was achieved with 100-50-50 N-P₂O₅-K₂O plus compost. Compost-based integrations averaged 3.35 mg ha⁻¹, while FOF-based integrations averaged 3.20 mg ha⁻¹. PFP ranged from 3.16 to 5.63 kg grain kg⁻¹ nutrient, with the highest value recorded for 100-50-50 NPK + FOF. Post-harvest soil fertility showed no significant changes, although integrated treatments tended to increase soil organic carbon (up to 1.47%). Conclusion: Nitrogen is the most limiting nutrient for wheat production in the semi-deciduous agroecological zone of Ghana, with optimal yields requiring more than 200 kg ha⁻¹ N, while modest P and K inputs (~30 kg ha⁻¹) are sufficient. Under the conditions of this study, combining mineral fertilizer with organic amendments improved nutrient use efficiency and grain yield. However, the absence of sole-organic amendment treatments in the second season precludes confirmation of synergistic interactions.