Spinach and Swiss Chard - 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).

Table 9-79. Spinach Nitrogen Recommendations

¹On muck soils, if rainfall has been excessive, an additional 55 kg/ha (50 lb/ac) may be side-dressed.

Broadcast and incorporate the recommended preplant nitrogen with all the required phosphate and potash. For early sown crops, apply the total nitrogen recommendation as a preplant application. See Table 9-79, Spinach Nitrogen Recommendations, above.

Phosphorus

Test the soil to determine phosphorus requirements. Where the soil test values are 61 mg P per L soil (ppm) or higher, spinach plants grown on both muck and mineral soils are unlikely to respond to additional phosphate applications. For soils testing lower than 61 mg P per L soil (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, spinach plants grown on both muck and mineral soils are unlikely to respond to additional potash applications. For soils testing lower than 181 mg K per L soil (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.

If phosphate and potash are required, apply and incorporate them prior to planting.

Micronutrients

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

Boron

Boron deficiencies on spinach and swiss chard are not common but may occur during periods of hot, dry weather. Leaves become twisted with light spots developing on the petioles. Internal breakdown may occur in the roots. External cankers may also develop on the root surface.

See the section Boron, on page 17, and Table 1-13, Application Rates for Magnesium, Calcium and Micronutrients, on page 16. Use caution when applying boron. This nutrient can build to toxic levels quite quickly, harming rotational crops.

Magnesium

A magnesium deficiency may occur on spinach. 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.

Plant Analysis

When used in conjunction with a soil analysis, plant analysis is a useful tool 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 sufficiency 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. For more information, see the section Plant Analysis, on page 3.

Table 9-80. Spinach Nutrient Sufficiency Ranges

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.

Plant Part: Most recently mature leaf

Only use sufficiency ranges as a reference and a guideline. Plant analysis does not replace soil testing or a sound soil fertility program. See Table 9-80, Spinach Nutrient Sufficiency Ranges, above.

Related Links

• Publication 363 - Vegetable Production Recommendations

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