Carrots - Fertility

Nitrogen

If manure is applied or legume sod is plowed down, reduce the nitrogen (N) application. See Table 1–8, Adjustment of Nitrogen Requirement Where Sod Containing Legumes Is Plowed Down, and Table 1–7, Average Amounts of Available Nutrients for Different Types of Manure, on page 9.

Broadcast and incorporate the recommended preplant nitrogen with all the required phosphate and potash. On mineral soils, apply side-dress nitrogen when the plants are 10 cm (4 in.) tall.

Table 9-13. Carrot Nitrogen Recommendations

Phosphorus

Test the soil to determine phosphorus requirements. Where the soil test values are 61 mg P per L soil (ppm) or higher, carrots grown on both mineral and muck soils are unlikely to respond to additional phosphate applications. For soils testing lower than 61 mg P per L (ppm), see Table 1–10, Phosphorus Requirements: Vegetables on Mineral Soils, on page 12, or Table 1–11, Phosphorus and Potassium Requirements: Vegetables on Muck Soils, on page 13.

Potassium

Test the soil to determine potassium requirements. Where the soil test values are 181 mg K per L soil (ppm) or higher, carrots grown on both mineral and muck soils are unlikely to respond to additional potash applications. For soils testing lower than 181 mg K per L (ppm), see Table 1–12, Potassium Requirements: Vegetables on Mineral Soils, on page 14, or Table 1–11, Phosphorus and Potassium Requirements: Vegetables on Muck Soils, on page 13.

Magnesium

Magnesium deficiency may occur on carrots. The usual symptoms are yellowing of older leaves while the veins remain dark green. See the section Magnesium, on page 15, and Table 1–13, Application Rates for Magnesium, Calcium and Micronutrients, on page 16.

Micronutrients

Crops vary greatly in their response to micronutrient fertilizers. For complete information, see the section Micronutrients, on page 16.

Boron

Boron deficiency in carrots can cause the growing point to die off or cause internal breakdown of the roots. Boron is often recommended on newly cultivated muck soils. Use caution when applying boron. This nutrient can built to toxic levels quite quickly, harming rotational crops.

Various sources of boron are available. See the section Boron, on page 17, and Table 1–13, Application Rates for Magnesium, Calcium and Micronutrients, on page 16.

Copper

Copper (Cu) deficiency may occur on acid peat and muck soils resulting in carrot roots with poor orange colour. Apply 14–29 kg Cu/ha (12.5–26 lb/ac) on newly cultivated muck soils. Subsequent applications may be made every 2 or 3 years at about one-third the rate recommended for new muck. See the section Copper, on page 18, and Table 1–13, Application Rates for Magnesium, Calcium and Micronutrients, on page 16.

Plant Analysis

When used in conjunction with a soil analysis, plant analysis can be useful for diagnosing crop problems or for evaluating a fertilizer program. The objective of a good fertilizer program is to maintain tissue nutrient concentrations on the lower side of the range. Attempting to bring the nutrient analysis up to the higher end of the range could possibly result in over-fertilization and may not be economical.

See Table 9–14, Carrot Nutrient Sufficiency Ranges. Only use sufficiency ranges as a reference and a guideline. Plant analysis does not replace soil testing, or a sound soil fertility program.

For more information, see the section Plant Analysis, on page 3.

Table 9-14. Carrot Nutrient Sufficiency Ranges

Plant Part: Most recently mature leaf

Adapted from Maynard, D.N., and G.J. Hochmuth. 1997. Knott’s Handbook for Vegetable Growers, 4^th Edition. John Wiley & Sons, Inc. New York.

ppm = parts per million

Related Links

• Publication 363 - Vegetable Production Recommendations

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