Response of Carrot (Daucus carota L.) to Combined Application of Cattle Manure, and NPSB Fertilizer on Growth, Quality, and Economic Analysis in Western Ethiopia

Carrot (Daucus carota L.) production is severely constrained by low soil fertility and poor nutrient management, particularly for smallholder farmers. In order to address this issue, a field study was carried out in 2024 at Wollega University's Gitilo Dale, Shambu Campus, to assess the combined effects of NPSB mixed fertilizer and cow manure (CM) on carrot growth, yield, quality, and economic performance. Four amounts of NPSB fertilizer (0, 60, 100, and 140 kg ha⁻¹) and four rates of cattle manure (0, 6, 10, and 14 t ha⁻¹) were used in the experiment, which was established in a 4 × 4 factorial design using a randomized complete block design with three replications. In comparison to the unfertilized control, the results demonstrated that combining cattle dung with NPSB fertilizer greatly increased vegetative growth, yield, and root quality. The combination of 10 t ha⁻¹ CM and 100 kg ha⁻¹ NPSB yielded the highest root yield (39.5 t ha⁻¹), the highest plant (34.8 cm), and the most leaves (14.2 per plant). Additionally, this treatment reduced root problems, disease occurrence, and insect damage while improving quality qualities like sugar content (7.8%), beta-carotene (9.5 mg 100 g⁻¹), and total soluble solids (8.6 °Brix). This treatment was the most profitable, according to economic evaluation, with a net benefit of 298,500 ETB ha⁻¹ and a benefit-cost ratio of 18.1. Overall, the combined use of cattle manure and NPSB fertilizer is an efficient and economically viable approach for enhancing carrot productivity and maintaining soil fertility in the study area.