2026/01/05 by Shiva Bhambota, M. Morrow, Varshitha Parsanna +2 · 1 voice
Agricultural and Biological Sciences · #Garlic and Onion Studies #Irrigation Practices and Water Management #Potato Plant Research
paper · doi:10.21273/hortsci19085-25
openalex created_date 2026/01/05 · openalex publication_date 2026/01/05 · openalex updated_date 2026/06/11
Carrots ( Daucus carota ) cultivated in the sandy soils of Florida require high nitrogen (N) application and are susceptible to nutrient loss, particularly nitrate (NO 3 -N) leaching. Controlled-release fertilizers (CRFs) are considered a promising alternative to optimize the carrot yield while reducing the nutrient leaching compared with conventional fertilizers. However, little is known about the efficacy of CRF in a carrot production system managed under well-drained sandy soils. A field study was conducted at the North Florida Research and Education Center–Suwannee Valley in Live Oak, FL in the 2021–22 and 2022–23 carrot growing seasons to compare CRF applications against conventional and combined CRF and conventional N applications. A two-factorial experimental design was implemented to evaluate the impact of different N treatments on carrot dry matter (DM) accumulation, N uptake, carrot quality, root yield, and nitrogen use efficiency (NUE). Plant growth parameters, including leaf tissue, DM, and multidepth soil samples, were collected throughout the growing season. The total DM accumulation and N uptake followed a typical sigmoidal trend over the carrot growing season, with tops DM and total N uptake increasing linearly until 100 to 120 days after planting, followed by a plateau and decline thereafter, and the storage root DM and N uptake increased linearly until harvest. The results showed no significant difference in DM accumulation and N uptake between the treatments. Remobilization of N was observed from carrot tops to storage roots during the later growing stages; consequently, the N content of the aboveground biomass declined from 133 to 171 kg N·ha −1 to 81 to 117 kg N·ha −1 across all the treatments, and nitrogen harvest index values increased to ∼51%. Overall, this study demonstrated that split application of CRF (112 kg·ha −1 at preplanting and 112 kg·ha −1 at 45, 55, and 65 days after planting) improved yield and maintained the soil NO 3 -N levels within the optimum levels throughout the growing season. Even though the conventional fertilizer was applied as a split application in the growing season, higher yield and NUE in CRF-managed carrots demonstrated the potential of CRF in sandy soils in Florida.