Nitrogen Fertilization to Maximize Carrot Yield and Quality on a Sandy Soil

Abstract

<jats:p>Nitrogen is required for successful carrot production on sandy soils of the southeastern United States, yet carrot growers often apply N in amounts exceeding university recommendations. Excessive fertilization is practiced to compensate for losses of N from leaching and because some growers believe that high rates of fertilization improve vegetable quality. Carrots (<jats:italic>Daucus carota</jats:italic> L.<jats:italic>)</jats:italic> were grown in three plantings during Winter 1994–95 in Gainesville, Fla., to test the effects of N fertilization on yield and quality. Yield increased with N fertilization but the effect of N rate depended on planting date; 150 kg·ha<jats:sup>–1</jats:sup> N maximized yield for November and December plantings but 180 kg·ha<jats:sup>–1</jats:sup> N was sufficient for the January planting. Concentration of total alcohol-soluble sugar was maximized at 45 mg·g<jats:sup>–1</jats:sup> fresh root with 140 kg·ha<jats:sup>–1</jats:sup> N for `Choctaw' carrots, whereas sugar concentration of `Scarlet Nantes' roots was not affected by N fertilization. Carrot root carotenoid concentration was maximized at 55 mg·kg<jats:sup>–1</jats:sup> fresh root tissue with 160 kg·ha<jats:sup>–1</jats:sup> N. Generally, those N fertilization rates that maximized carrot root yield also maximized carrot quality as determined by sugar and carotenoid concentrations.</jats:p>

Timing Nitrogen Applications for Quality Tops and Healthy Root Production in Carrot

“…When N is the limiting nutrient, increasing the N supply usually enhances top (shoot) growth more than root growth, resulting in a lower root/shoot ratio (Marshner 1998;Hochmuth, Brecht, and Bassett 1999;Warncke 1996). In our study, tops continued to accumulate N up to the 180 kg ha −1 rate (treatment 4) at most locations; nevertheless it was not reflected in the yield (Table 4).…”

“…Temperatures ranging from 16 to Nitrogen Timing for Carrot Top and Root Quality 2861 21 • C promote greater sugar accumulation in the roots (Epps 1970;Fritz et al 1998;Golz and Aakre 1993;Mills 2001;Zandstra et al 1986). Loose, deep, and well-drained coarse mineral or organic soils are favorable for growing straight carrot roots, whereas heavy, stony, or compacted soils obstruct root growth, causing forked and misshapen roots (Epps 1970;Fritz et al 1998;Golz and Aakre 1993;Hanlon, Hochmuth, and Campbell 2000;Hochmuth, Brecht, and Bassett 1999;McGiffen et al 1997;Michigan Department of Agriculture 2002;Mills 2001;Zandstra et al 1986). In Michigan, carrots are grown both in deep, well-drained muck with a pH range of 5.5 to 6.2 and in sandy mineral soils with a pH range of 6.2 to 6.8 (Bronick et al 1999;Zandstra et al 1986).…”

Minimal nitrogen and water use in horticulture: Effects on quality and content of selected nutrients

“…Applied N at the highest rate generally resulted in higher carotenoids in apples (Reay et al, 1998), carrot (Hochmuth, Brecht, & Bassett, 1999), kale (Kopsell, Kopsell, & Curran-Celentaro, 2007), while mid-range applications were most effective in tomatoes (Dorais, 2007;Simonne, Fuzere, Simonne, Hochmuth, & Marshall, 2007), lettuce (CoriaCayupan et al, 2009) and watercress (Kopsell, Barickman, Sams, & McElroy, 2007) (Table 1). A decrease in NO À 3 from 12 to 4 mM/plant resulted in a slight reduction in tomato yield (7.5%), and an increase in fruit eating quality as determined by lower fruit acidity and higher soluble sugars (Be'nard et al, 2009) Bryant et al, 1983).…”

Variation in moisture, total sugar, and carotene content of Japanese carrots: Use in sample size determination

“…bCarotene content is reported to increase during storage (Brown, 1949;Clydesdale et al, 1991;Lee, 1986;Rygg, 1949), and some of the samples obtained in February for this study were storage samples. Hochmuth et al (1999) reported that b-carotene concentrations are influenced by nitrogenous fertilizers. In the Mie prefecture, larger amounts of fertilizer are recommended for use in the summer (25 kg/km 2 ) than in the winter (20 kg/km 2 ).…”