Carrot Productivity and Economic Benefits as Influenced by Different Rates of Chicken Manure and NPK Fertilizer

This study assessed the productivity and economic returns of chicken manure (CM) and NPK fertiliser, applied alone and in combination, in carrot (Daucus carota L.) production at Mampong-Ashanti during September–December 2021 and April–July 2022. The experiment used a randomised complete block design with six treatments and four replications: 300 kg ha⁻¹ NPK (full NPK), 20 t ha⁻¹ CM (full CM), ¾ NPK + ¼ CM, ½ NPK + ½ CM, ¼ NPK + ¾ CM, and an unfertilised control. Full CM in 2021 and ¼ NPK + ¾ CM in 2022 produced significantly higher root yields than the control. Economic analysis showed that full CM generated the highest net benefit in 2021 (USD 4,911.68 ha⁻¹), whereas ¼ NPK + ¾ CM generated the highest net benefit in 2022 (USD 5,503.31 ha⁻¹). Although full CM incurred the highest total variable cost (USD 469.64 ha⁻¹), its yield performance maintained its economic attractiveness. In 2021, ½ NPK + ½ CM produced a marginal rate of return (MRR) of 55.48% over the control, while full CM produced an MRR of 638.15% over ½ NPK + ½ CM. In 2022, ¼ NPK + ¾ CM had higher MRR (708.44%) than ½ NPK + ½ CM. The results indicate that 20 t ha⁻¹ CM may be suitable in the minor season, whereas ¼ NPK + ¾ CM may be suitable in the major season for improving carrot yield and profitability.