Soil & Fertility
Deep sandy to loamy soil with a pH of 6.5 to 7.5 is ideal for eggplant, pepper, and tomato production. Most soils in Utah are suitable for production, provided they are well-drained, fertile, and do not have a buildup of salt. Rotate the location of your crop every 1 to 2 (tomato) or 3 (pepper and eggplant) years to soil where solanaceous plants (eggplant, pepper, tomato, or potato) were not previously grown in the preceding three years to reduce the buildup of soil-borne diseases. A loose, somewhat dry, tilled soil is ideal for transplanting eggplant, pepper, and tomatoes to ensure good soil contact with the transplant root ball. Tomato plants are sensitive to herbicides in soil; select sites without herbicide residues.
Prior to planting, test the soil to determine nutrient needs and deficiencies. If over-fertilized, yield, earliness, or fruit quality may suffer (Fig 9.2). Incorporate composted organic matter before planting to sustain soil fertility. An initial application of 5 tons per acre of high quality compost of known nutrient analysis is recommended. For synthetic fertilizers, apply half the recommended nitrogen and all the phosphorous and potassium, based on soil test results, prior to planting (Peet 2005).
Fig. 9.2. Proper fertilization can lead to better yield and fruit quality
Eggplant and Pepper
Nitrogen (N) - Incorporate 50-75 lb/acre nitrogen prior to planting, and an additional 150-200 lb/ acre throughout the growing season. Following this fertilization protocol will ensure plants keep growing for the whole season. Use a lower rate for eggplant to avoid excessive leaf growth and delayed flowering.
Phosphorus (P) - Incorporate 50–200 lb/acre phosphorous prior to planting depending on the soil analysis if extractable phosphorous is less than 15 ppm. Higher rates of P may be needed for early plantings when soils are cold or if soil pH is 7.5 or above.
Potassium (K) – Incorporate 50–150 lb/acre Potassium prior to planting depending on the soil analysis if extractable potassium is less than 150 ppm.
Nitrogen (N) – Incorporate 50-75 lbs/acre nitrogen prior to planting, and another 50-75 lbs/N when first fruits are 1” in diameter. Use the smaller amount if manure or compost has been applied to the soil.
Phosphorous (P) – Incorporate 50–150 lbs/acre phosphorous prior to planting depending on soil analysis. Use 150 lbs/acre if phosphorous is low (25 ppm).
Potassium (K) – Incorporate 60–180 lbs/acre potassium prior to planting depending on the soil analysis. Use 180 lbs/acre if potassium is low (250 ppm).