SUSTAINABLE CARROT PRODUCTION TECHNOLOGIES: THE INTERACTIVE EFFECTS OF SOIL MOISTURE AND NITROGEN FERTILIZATION ON THE YIELD AND RECOVERY OF SLICER CARROTS
Ground water contamination as a result of excess nitrogen fertilizer applications is becoming a major concern. Since N uptake, utilization and leaching can depend on irrigation, it is important to understand and regulate N applications to minimize leaching and optimize yield and recovery. A field experiment was conducted during 2005 to investigate the interactive effects of N fertilization and irrigation on yield and recovery in slicer carrots (Daucus carota). 7 levels of Nitrogen (0, 55, 110, 165, 220, 330, 440 kg·ha-1) were applied to 2 adjacent blocks of 'Carochoice' carrots. The first block received irrigation to maintain the soil moisture potential at -40 cbar throughout the growing season. The second block did not receive any irrigation in addition to the natural rainfall. Soil samples were taken at 2 depths prior to the first and second N applications and again at final harvest. Leaf and root tissue samples were taken prior to the second N application and at final harvest. Plots were harvested on October 6, 2005 and observations were made on yield, recovery of marketable grades, leaf biomass, root length, girth, as well as gas exchange parameters. There were significant interactions for leaf fresh weight, root girth and length. Application of high amounts of N (330 and 440 kg·ha-1 N) under no irrigation produced the longest roots. Irrigation combined with 110 or 165 kg·ha-1 N resulted in a significantly higher yield than the non-irrigated control plots. A significantly higher percentage of fancy grade roots were seen in the irrigated plots which received 110 kg·ha-1 N compared to the unirrigated control (0 kg·ha-1 N) plots. No significant advantages in yield or recovery of fancy grade roots was gained by applying more than 165 kg·ha-1 N. There was no enhancement in net photosynthesis, leaf transpiration or water use efficiency due to N fertilizer application or irrigation. Stomatal conductance however, was significantly higher in the irrigated control (0 kg·ha-1 N). Optimizing N and irrigation can result in sustainable carrot production and facilitate environmental safety.
Lada, R.R. and Adams, A. (2008). SUSTAINABLE CARROT PRODUCTION TECHNOLOGIES: THE INTERACTIVE EFFECTS OF SOIL MOISTURE AND NITROGEN FERTILIZATION ON THE YIELD AND RECOVERY OF SLICER CARROTS. Acta Hortic. 767, 211-216
nitrogen fertilizer, irrigation, yield, recovery, soil moisture potential