Cucurbits - 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, on page 9, and Table 1-7, Average Amounts of Available Nutrients for Different Types of Manure, on page 9.)

Apply up to 110 kg N/ha (98 lb N/ac). Broadcast 65 kg N/ha (58 lb/ac) and all the phosphate and potash required prior to planting. Side-dress the remainder of the nitrogen before the vines start to run. On sandy soils, a second application may be necessary after the vines begin to run.

Alternatively, up to 100 kg (90 lb) of N + K20/ha can be applied in a band, 5 cm to the side and 5 cm below the seed at planting. The remainder of the fertilizer requirements should be broadcast before planting. Over-application of nitrogen may result in excessive vine growth and reduced fruit yields.

Phosphorus

Test the soil to determine phosphorus requirements. Where the soil test values are 61 mg P per L soil (ppm) or higher, cucurbit fields 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.

Potassium

Test the soil to determine potassium requirements. Where the soil test values are 181 mg K per L soil (ppm) or higher, cucurbit fields 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.

Fertigation

For fertigated vine crops, broadcast all the phosphate requirement and approximately 30%-50% of the nitrogen and potash requirements prior to planting. The remainder should be injected through the drip irrigation system at the rates shown in Table 9-31, Cucurbit Nitrogen and Potash Injection Schedules.

Table 9-31. Cucurbit Nitrogen and Potash Injection Schedules

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.

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 9-32, Cucurbit Nutrient Sufficiency Ranges, below.

Table 9-32. Cucurbit 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.

Cucumber - Plant Part: Most recently mature leaf

Muskmelon - Plant Part: Most recently mature leaf

Pumpkin - Plant Part: Most recently mature leaf

Squash - Plant Part: Most recently mature leaf

Watermelon - Plant Part: Most recently mature leaf

Related Links

• Publication 363 - Vegetable Production Recommendations

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