Response of carrot (Daucus carota Linn.) to different doses and sources of nitrogen in Sindhuli, Nepal

As a root crop known for its substantial nitrogen requirements, carrot responds well to both organic and inorganic fertilizers that supply different amounts of nitrogen. This study aimed to assess the efficacy of various proportions of farmyard manure (FYM) and recommended dosages of chemical fertilizers (RDF) in carrot production to address the issues posed by their sole use. A Randomized Complete Block Design (RCBD) was used to plan the field study, which consisted of five treatments and five replications with different nitrogen rates and sources, viz., T1 (100% FYM), T2 (25% RDF+75% FYM), T3 (50% RDF+50% FYM), T4 (75% RDF+25% FYM), and T5 (100% RDF) during December 2019 to April 2020 in the tropical region of Sindhuli, Nepal. Among the treatments, T3 exhibited the earliest germination (7.60 DAS) and the most desirable plant height (42.61 cm), root length (20.41 cm), root diameter (3.01 cm), fresh root weight plant-1 (96.04 g), total root dry matter content (15.01%), root biomass plant-1 (55.44 g), and total biomass plant-1 (85.33 g) at harvest. However, T5 resulted in the highest leaf count plant-1 (8.6) and fresh foliage weight plant-1 (42.96 g) at harvest. Similarly, T3 was significantly higher for quality parameters, such as cortex diameter (1.36 cm), pH (6.72), TSS (12.48 0Brix), TA (0.22 g liter-1), and organoleptic score (7.60). Although there were minimal root disorders in T3 (17%), T1 also had insignificant cases of cracking (8%) and postharvest weight loss (1.63%). Thus, reducing nitrogen input from the recommended dose and adding FYM improves carrot yield, quality, and shelf life. Furthermore, this guarantees higher economic returns with a B:C ratio of 1.65. Despite these positive results, the efficacy of the tested nutrient combinations needs to be analyzed on a larger scale, as well as in different ecological regions.