Practical Guide to Eggplant Nutrition: From Soil to Harvest

Why Nutrition Is Critical

Eggplant forms a robust bush with large leaves and relatively large fruits. For this, the plant requires a significant amount of nutrients throughout the growing season. Unlike many other vegetable crops, eggplant has a poor root system recovery capacity: damaged roots regenerate slowly, and it tolerates deep planting worse than tomato (Autko et al., 2012). This makes it especially important to create a favourable nutrient background in the root zone from the very beginning of cultivation.

The root system of eggplant is taprooted, branched, penetrating to a depth of up to 1 m; however, the bulk of the roots is concentrated in the topsoil. Active root hairs are located mainly in the upper soil layer, which determines the crop's high demands for fertility, water, and air‑gas regime of the soil (Autko et al., 2012). The optimum soil moisture for eggplant is 75–80% of full field water capacity, while air humidity should be at 60–70%.

Role of Balanced Nutrition

Balanced nutrition ensures:

1. Optimal growth and development. Eggplant is a crop with an intensive growth type. Disruption of nutrition at any development phase leads to an irreversible reduction in productivity. The periods of budding, flowering, and fruit set are especially critical, when the demand for nutrients is highest (Tarakanov & Mukhin, 2003).

2. Formation of high‑quality fruits. The chemical composition of eggplant fruits includes dry matter (up to 9%), sugars (up to 5.2%), proteins, B vitamins, ascorbic acid, and mineral salts (Tarakanov & Mukhin, 2003). Balanced nutrition directly affects the content of these components. Young fruits contain significant amounts of tannins and organic acids, giving them a characteristic bitterness; as they mature, the content of these substances decreases while sugar content increases (Tarakanov & Mukhin, 2003).

3. Increased disease resistance. Plants receiving adequate nutrition have stronger immunity. Potassium deficiency, for example, reduces resistance to fungal diseases, while calcium deficiency provokes blossom‑end rot of fruits (Hochmuth & Sideman, 2023). Blossom‑end rot in eggplant occurs when water regime is disrupted and calcium is deficient, especially in combination with excess magnesium in the soil (Autko et al., 2012).

4. Early and uniform ripening. Properly organised nutrition accelerates phenological phases and allows an earlier harvest. This is especially important for regions with a short growing season, where eggplant is grown through transplants.

Nutritional Specifics of Eggplant Compared to Other Nightshades

Eggplant is more demanding of heat than tomato and pepper. The optimal temperature for its growth and fruiting is 22–30 °C during the day and 18–24 °C at night (Rubatzky & Yamaguchi, 1997). At temperatures below 17 °C, growth slows down, and flowering and fertilisation are weak (Tarakanov & Mukhin, 2003). This heat and moisture requirement affects the nutrition regime: at low temperatures, roots absorb nutrients less well, especially phosphorus and micronutrients. Therefore, in cool weather, even sufficient fertiliser in the soil may not produce the expected effect.

Eggplant is sensitive to soil salinity and high concentration of the soil solution (Hochmuth & Sideman, 2023). Therefore, when applying fertilisers, it is important to observe moderation: excess salts can cause root burn and reduced productivity, especially on light soils.

Biological Features Determining Nutrition Strategy

Understanding eggplant biology helps build an effective nutrition system:

• Indeterminate growth type – the plant continuously produces new shoots and flowers, so the need for nutrients persists throughout the growing season.
• Large leaves – intensive photosynthesis requires high supplies of nitrogen and magnesium.
• Berry‑type fruits – potassium and phosphorus are needed for fleshy fruit formation.
• Sensitivity to stress – under moisture or nutrient deficiency, plants may drop flowers and ovaries, sharply reducing yield.

Thus, the importance of nutrition for eggplant cannot be overstated. It is not just an "add‑on" to agronomic practices, but one of the key factors determining growing success. A well‑designed fertiliser system that accounts for plant development phases, soil type, and climatic conditions allows consistently high yields of quality fruit.

Macronutrients: The Foundation of Eggplant Nutrition

Secondary Nutrients

Micronutrients: Importance of Small Doses

Although micronutrients are required by eggplant in very small quantities, their deficiency can seriously limit yield and product quality. Eggplant is sensitive to deficiencies of zinc, boron, manganese, iron, molybdenum, and copper. Micronutrient deficiency is especially pronounced under high agronomic backgrounds (intensive macronutrient nutrition), where element ratios may be disturbed (Autko et al., 2012).

Quantitative Guidelines for Element Uptake by Eggplant

Although exact figures for nutrient removal by eggplant vary depending on yield, variety, and conditions, approximate data can be given for planning fertiliser systems (based on generalised data for nightshades, e.g., tomato and pepper, adjusted for eggplant specificity) (Lorenz & Maynard, 1980; Nonnecke, 1989; Rubatzky & Yamaguchi, 1997).

Table 1 — Approximate nutrient removal rates by eggplant crop (per 1 tonne of marketable produce)

Note: These values are approximate and can vary significantly depending on soil fertility and applied practices.

Based on these data, you can calculate the total nutrient requirement for the planned yield and adjust rates considering the existing soil nutrient content (from agrochemical analysis).

Organic Fertilisers

Organic fertilisers play an important role in eggplant nutrition, especially during soil preparation. They improve soil structure, increase water‑holding capacity and air permeability, stimulate beneficial microorganism activity, and serve as a source of nutrients gradually released during mineralisation (Autko et al., 2012; Tarakanov & Mukhin, 2003).

Main types of organic fertilisers:

• Farmyard manure (well‑rotted) – the most valuable organic fertiliser for eggplant. It is applied for autumn or spring digging. Recommended rate – 40–60 t/ha (4–6 kg/m²) (Autko et al., 2012). Manure not only enriches the soil with nutrients but also improves its physical properties, which is especially important for eggplant with its sensitive root system. Fresh manure is not recommended for eggplant, as it can cause root burn and promote disease development (Autko et al., 2012).

• Compost – an excellent alternative to manure. It can be made from plant residues, food waste, peat, sawdust. Quality compost contains a balanced set of nutrients and improves soil structure. Application rates – 30–60 t/ha (3–6 kg/m²) (Tarakanov & Mukhin, 2003). It is important that the compost is fully mature (rotted), otherwise it may become a source of weeds or diseases.

• Green manures (cover crops) – another way to enrich soil with organic matter. Legume green manures (lupine, pea, vetch) enrich soil with nitrogen, while cereals (oats, rye, mustard) improve structure and suppress weeds. Green manures are ploughed in autumn or early spring 2–3 weeks before planting eggplant. This is especially relevant for poor soils and in organic farming.

Advantages of organic fertilisers:

• Gradual nutrient release, reducing the risk of overdose
• Improvement of soil structure and microbiological activity
• Increased water‑holding capacity (especially on light soils)
• Environmental safety

Disadvantages:

• Low content of major nutrients (per unit mass)
• Need for large volumes to achieve effect
• Risk of introducing weed seeds and pathogens when using poor‑quality compost
• Difficulty in precise nutrient dosing

Mineral Fertilisers

Mineral fertilisers are the main source of rapid and precise nutrient supply for eggplant. They are divided into straight (containing one nutrient) and compound (containing two or more nutrients).

Compound and Complex Fertilisers

Compound fertilisers contain several nutrients and simplify application, as they provide balanced nutrition. For eggplant, the following types are suitable:

• Nitroammophoska (azophoska) – contains N, P₂O₅, K₂O in various ratios (e.g., 16:16:16 or 19:9:19). A universal fertiliser that can be used as basal and in top‑dressings. For eggplant, formulas with higher potassium and phosphorus content are preferred (e.g., 13:19:19 or 12:24:12) (Autko et al., 2012).

• Complex water‑soluble fertilisers (fertigation grades) – these are special fertilisers fully soluble in water, with micronutrients. For example, formulas 20:20:20 + ME (for early growth), 15:30:15 + ME (for flowering and fruit set), 12:12:36 + ME (for fruiting). They are used in drip irrigation or for foliar sprays. This is the most precise way to manage nutrition (Hochmuth & Sideman, 2023; Autko et al., 2012).

• Complex fertilisers with micronutrients – many manufacturers produce granulated and liquid fertilisers enriched with micronutrients (boron, zinc, manganese, copper, iron, molybdenum). This is convenient for comprehensive plant nutrition. However, it is important to check which micronutrients and in what form are present to cover possible deficiencies.

Micronutrient Fertilisers

As already mentioned, eggplant is sensitive to micronutrient deficiencies. They are applied as part of compound fertilisers or as separate products. Main forms of micronutrient fertilisers:

• Chelated forms – the most effective for foliar feeding, as micronutrients are in readily available form and are not fixed in the soil. Chelates of iron, zinc, manganese, copper are used. Dosages are usually indicated on the packaging and are 0.01–0.05% of active ingredient.

• Sulphate forms – zinc sulphate, manganese sulphate, copper sulphate, iron sulphate. They are used both for root application (soil incorporation) and for foliar feeding. On alkaline soils, effectiveness decreases, so they are more often used for foliar treatments.

• Boron fertilisers – boric acid (17% B), borax (11% B). Boron is applied both to soil (0.5–1 kg/ha of active ingredient) and as foliar sprays during budding and flowering.

Controlled‑Release Fertilisers

In recent years, fertilisers with controlled release (slow‑release) have become increasingly widespread. These are granules coated with special polymer or sulfur coatings that gradually release nutrients over several weeks or months depending on soil temperature and moisture (Hochmuth & Sideman, 2023). For eggplant, such fertilisers may be useful when growing in containers, on light soils, or when frequent top‑dressings are limited. However, on large areas and with drip irrigation, water‑soluble fertilisers are more commonly used for precise nutrition control.

Comparative Characteristics and Fertiliser Selection

Practical Selection Recommendations

1. For basic soil preparation (autumn or spring), it is best to use organic fertilisers (manure, compost) combined with phosphorus‑potassium mineral fertilisers and part of the nitrogen. This creates a good initial nutrient background.

2. For top‑dressings during the growing season, water‑soluble compound fertilisers with micronutrients are preferred, as well as calcium nitrate (as an additional source of nitrogen and calcium) and potassium sulphate (for potassium top‑dressings). They are quickly absorbed and allow precise nutrient adjustment according to growth phase.

3. When signs of micronutrient deficiency appear, apply foliar sprays with chelated forms of the respective elements.

4. On light sandy soils, it is recommended to use controlled‑release fertilisers and split application to avoid nutrient leaching.

5. Always rely on the results of soil agrochemical analysis – this helps avoid both deficiency and excess of nutrients.

4.1. Soil Requirements for Eggplant

Eggplant is demanding of soil conditions. It grows well on light, well‑drained, organic‑matter‑rich soils with neutral or slightly acidic reaction. The optimal pH range is from 6.0 to 6.8 (Hochmuth & Sideman, 2023; Autko et al., 2012). On acidic soils (pH < 5.5), phosphorus, calcium, and magnesium availability decrease, and the risk of root rots increases. On alkaline soils (pH > 7.5), iron, manganese, zinc, and boron uptake deteriorates, which can lead to chlorosis and other nutritional disorders.

Eggplant does not tolerate salinity or excessive soil moisture. The root system is sensitive to oxygen deficiency, so the soil must be loose and well‑aerated. Heavy clayey soils prone to pudding and waterlogging are unsuitable for eggplant without prior improvement (addition of sand, peat, organic matter, creation of beds or ridges) (Tarakanov & Mukhin, 2003; Swiader & Ware, 1992).

Sandy loam and light loamy soils, well warmed and quickly drying in spring, are most preferred. On such soils, eggplant enters fruiting earlier and gives higher yields. However, with good agronomic practices and adequate irrigation, it can also be grown on cultivated loams.

4.2. Predecessors and Crop Rotation

Correct choice of predecessor is an important element of disease prevention and balanced nutrition. Eggplant, like other nightshades, should not be planted after tomatoes, potatoes, peppers, or other crops of the same family earlier than after 3–4 years. This is due to the accumulation of specific pathogens in the soil (causing Fusarium and Verticillium wilts, Phytophthora, nematodes) and one‑sided depletion of nutrients (Autko et al., 2012; Tarakanov & Mukhin, 2003).

Best predecessors for eggplant:

• Legumes (peas, beans, broad beans, lupine) – they enrich the soil with nitrogen.
• Cucumbers, zucchini, pumpkins – they have no common diseases with nightshades and leave loose soil.
• Cabbage (all types) – a good predecessor, especially with organic matter application.
• Onion, garlic, carrot, beet – provided good soil tillage.
• Green manure crops (mustard, phacelia, rye, oats) – they are ploughed in autumn or spring, improving soil health and enriching it with organic matter.

It is not recommended to plant eggplant after sunflower, sorghum, or after crops that greatly deplete the soil (e.g., maize). Ideally, the site should be protected from cold winds and well sunlit (Tarakanov & Mukhin, 2003).

4.3. Soil Preparation

Soil preparation for eggplant begins in autumn, immediately after harvesting the predecessor. Main steps:

Autumn tillage:

1. Removal of plant residues. All residues of the previous crop are removed from the field or incorporated only if healthy. Diseased plants are better burned or removed.

2. Application of organic fertilisers. Under autumn ploughing, apply manure or well‑rotted compost at 40–60 t/ha (4–6 kg/m²). On poor soils, increase the rate to 80–100 t/ha. Organic matter improves structure, increases water‑holding capacity, and serves as a nutrient source for microorganisms. Fresh manure should not be applied to eggplant in autumn (it is better to apply it under the predecessor) (Autko et al., 2012; Tarakanov & Mukhin, 2003).

3. Application of phosphorus and potassium fertilisers. Phosphorus and potassium are immobile in soil, so the main part (60–80% of the calculated dose) is applied in autumn under ploughing. Phosphorus fertilisers (double superphosphate – 80–120 kg/ha P₂O₅) and potassium fertilisers (potassium sulphate – 100–150 kg/ha K₂O) are incorporated to the depth of the arable layer (25–30 cm) (Autko et al., 2012; Swiader & Ware, 1992).

4. Deep ploughing. Autumn ploughing is done to a depth of 25–30 cm with mouldboard turning (with a skim coulter). This incorporates fertilisers, mixes the soil, destroys weeds and pests, and creates a loose layer for deep root penetration.

5. Liming (if necessary). If the soil is acidic (pH < 5.5), apply dolomite lime or limestone (0.5–1 kg/m² depending on acidity) in autumn. Liming improves phosphorus, calcium, and magnesium uptake and reduces aluminium and manganese toxicity. Do not mix lime with phosphorus fertilisers (especially superphosphate), as phosphorus is fixed. Apply them separately, with an interval of at least one month (Hochmuth & Sideman, 2023; Autko et al., 2012).

Spring tillage:

Early spring, as soon as the soil allows, harrow to conserve moisture. Then cultivate to a depth of 10–12 cm for loosening and levelling. Just before planting (1–2 days before), carry out pre‑plant cultivation to a depth of 15–18 cm (or plough without turnover) with simultaneous application of the remaining fertilisers (especially nitrogen) and forming beds or ridges (Autko et al., 2012; Tarakanov & Mukhin, 2003).

In regions with excessive moisture and on heavy soils, it is recommended to grow eggplant on raised beds or ridges (20–25 cm high), which ensures better drainage and soil warming. Ridges are formed 1–2 weeks before planting to allow settling.

4.4. Basal Mineral Fertiliser Application (Starter)

Basal application refers to fertilisers incorporated into the soil before planting (autumn and/or spring). It creates a starting reserve of nutrients available to the root system in the initial growth period. Basal rates are calculated based on soil agrochemical analysis and planned yield. However, if analysis is unavailable, approximate rates for medium soils can be used.

Approximate basal application rates for eggplant (kg/ha of active ingredient) for a planned yield of 30–40 t/ha (Autko et al., 2012; Swiader & Ware, 1992):

• Nitrogen (N) – 50–80 kg/ha (usually 30–40% of total seasonal rate) applied in spring before planting. The remainder is applied in top‑dressings.
• Phosphorus (P₂O₅) – 100–140 kg/ha (80–100% of total) applied in autumn or spring (preferably autumn).
• Potassium (K₂O) – 120–180 kg/ha (60–80% of total) applied in autumn (preferably) or spring.

On poor sandy soils, increase rates by 20–30%. On humus‑rich soils, the nitrogen part of the basal application can be reduced, as organic matter will mineralise (Hochmuth & Sideman, 2023). Phosphorus and potassium on light soils also require higher rates due to leaching.

Element ratios: for eggplant, a ratio of N : P₂O₅ : K₂O of approximately 1 : 1.5–2 : 2–2.5 is recommended. This means that potassium and phosphorus are needed more than nitrogen, especially to stimulate fruiting. For example, for basal application, you could take 60 kg N, 120 kg P₂O₅, and 150 kg K₂O per hectare.

Forms of fertilisers for basal application:

• Nitrogen – best to use ammonium nitrate (quick‑acting) or calcium nitrate (to supply calcium), but the latter is more expensive. Nitrogen fertilisers are applied surface or locally in spring.
• Phosphorus – double superphosphate (46% P₂O₅) – the best choice.
• Potassium – potassium sulphate (50% K₂O) – preferred over potassium chloride.

4.5. Local (Starter) Application in Holes or Furrows

In addition to basal application, at transplanting it is recommended to apply a small amount of fertiliser directly into the planting hole or furrow. This gives the plant access to nutrients in the earliest period, when the root system is still weak and cannot effectively explore the entire soil volume. This "starter" charge is especially important for phosphorus, which is immobile and poorly absorbed from the bulk soil.

What can be applied to the hole:

• Phosphorus‑potassium mixture – 5–10 g of double superphosphate and 5–10 g of potassium sulphate per hole (or 10–15 g of compound fertiliser with a predominance of phosphorus and potassium, e.g., 12:24:12).
• Manure or compost – 0.5–1 handful per hole (especially on poor soils).
• Wood ash – a good source of potassium, phosphorus, and micronutrients (1–2 tablespoons per hole), but not on alkaline soils.

Important: fertilisers are thoroughly mixed with soil at the bottom of the hole to avoid root contact with high salt concentrations, which could cause burn. You can also apply a solution of compound fertiliser when watering the seedlings.

Starter solutions (for seedling watering) – use diluted solutions of water‑soluble fertilisers (e.g., 0.2–0.3% solution of potassium monophosphate or compound fertiliser 20:20:20) at 0.5–1 L per plant. This promotes rapid rooting.

4.6. Accounting for Soil Fertility and Dose Adjustment

Basal fertiliser application should be strictly differentiated according to soil type and fertility. Here are general guidelines for adjustment:

Note: on soils with high organic matter content, nitrogen fertiliser can be reduced, as part of nitrogen is released during mineralisation. On soils with high available phosphorus and potassium, these elements can be applied in lower doses.

4.7. Micronutrients in Basal Application

During basic soil preparation, it is useful to add micronutrients, especially if soils are poor or specific deficiencies are common in the region. Usually, micronutrients are added as part of compound fertilisers or separately, based on agrochemical service recommendations. On medium‑fertility soils, you can limit to adding boron (0.5–1 kg/ha of boron) and zinc (1–2 kg/ha of zinc) as part of the basal fertiliser. On acidic sandy soils, molybdenum and copper may be needed (Autko et al., 2012; Swiader & Ware, 1992).

Practical Recommendations

1. Do soil analysis at least once every 3–4 years – this allows precise dose adjustment and avoids overuse or deficiency.

2. Apply organic matter in autumn – over winter it will be processed by microorganisms and become available to plants in spring. In spring, only well‑rotted manure can be applied.

3. Apply phosphorus and potassium mainly in autumn – they do not leach, and by spring they are evenly distributed in the plough layer.

4. Apply nitrogen fertilisers in spring, part (30–40%) before planting, the rest in top‑dressings, as nitrogen is mobile and can be leached by winter precipitation.

5. Local application in holes or furrows (a small amount of well‑balanced fertiliser) is an excellent practice for eggplant, as it provides early nutrition and stimulates root formation.

6. On heavy soils, be sure to create beds or ridges so that the root system does not suffer from waterlogging.

5.1. General Principles of Eggplant Top‑Dressing

Before moving to specific schemes, it is important to grasp several key rules:

1. Split application. Eggplant, as a crop with a long fruiting period, responds better to frequent application of small doses than to a single large dose. This is especially important on light soils, where nutrients are quickly leached (Hochmuth & Sideman, 2023; Autko et al., 2012).

2. Potassium priority during fruiting. During fruit filling, potassium demand rises sharply. It is responsible for fruit quality, taste, and storage life. The N : K₂O ratio during this period should shift toward potassium (e.g., 1 : 1.5–2) (Autko et al., 2012; Rubatzky & Yamaguchi, 1997).

3. Nitrogen – in early growth. Nitrogen is mainly needed in the first half of the growing season for building a strong photosynthetic apparatus. During mass fruiting, its share is reduced to avoid excessive leaf growth at the expense of fruits and nitrate accumulation (Swiader & Ware, 1992).

4. Phosphorus – constant companion. Phosphorus is needed at all stages, but is especially critical during flowering and fruit set, and for root development after transplanting.

5. Calcium – prevention of blossom‑end rot. Calcium must be maintained at adequate levels throughout the fruiting period, especially with uneven irrigation (Hochmuth & Sideman, 2023).

6. Micronutrients – in critical windows. The greatest need for micronutrients occurs during active growth (boron, zinc, manganese, iron) and during flowering‑fruit set (boron).

5.2. Growth Phases and Top‑Dressing Objectives

Conventionally, the growing season of eggplant can be divided into the following phases:

5.3. Feeding in the Seedling Stage

Quality seedlings are the key to future harvest. During the seedling stage, it is important not to over‑feed, but to supply everything needed for a healthy root and compact bush.

Timing and compositions:

• First feeding (at 2–3 true leaves, 10–14 days after pricking out). Main goal – stimulate root growth and stem strengthening. Use a solution of compound fertiliser with a predominance of phosphorus (e.g., 10:20:10 or 15:30:15 + ME) at 0.1–0.2% concentration. Application rate – 3–5 L per 1 m² (Autko et al., 2012; Tarakanov & Mukhin, 2003).

• Second feeding (12–14 days after the first, 10–15 days before transplanting). At this stage, a balanced composition with a slight increase in potassium is needed (e.g., 14:14:14 or 13:20:13). Calcium nitrate (0.5%) can also be used to prevent later blossom‑end rot.

• Foliar feeding with micronutrients (7–10 days before transplanting) – spraying with a solution of chelated micronutrients (Fe, Zn, Mn, B, Mo) at low concentration (0.01–0.02%) helps prepare plants for transplanting stress (Autko et al., 2012).

Important: do not allow seedlings to overgrow (age more than 60–70 days) or excessive nitrogen nutrition, which leads to elongation and poor establishment. Optimal temperature, lighting, and watering are also critical at this stage (Swiader & Ware, 1992).

5.4. Feeding After Transplanting (Rooting Phase)

After transplanting into open ground or a greenhouse, eggplant experiences stress; its root system is partially damaged. In the first 7–14 days, plants adapt, so feeding during this period should be gentle but stimulating new root formation.

Recommendations:

• 7–10 days after transplanting, give a starter feeding with a predominance of phosphorus and potassium, e.g., a solution of potassium monophosphate (0.2–0.3%) or compound fertiliser 12:24:12 + ME. Rate – 0.3–0.5 L of working solution per plant or 3–5 L per 1 m² when watering in furrows (Autko et al., 2012). Phosphorus stimulates root growth, potassium increases stress resistance.

• You can also use potassium or sodium humate (according to instructions) to improve establishment and reduce stress.

• At this stage, it is not recommended to apply high nitrogen doses, as it can stimulate leaf growth at the expense of root formation and slow adaptation (Rubatzky & Yamaguchi, 1997).

• If the weather is hot, it is better to combine feeding with watering to avoid root burn.

5.5. Feeding During Active Vegetative Growth

After rooting (usually 2–3 weeks after transplanting), eggplant begins to actively build up leaf mass. During this period, nitrogen demand increases. However, moderation is important: excess nitrogen will cause excessive "luxuriant" shoot growth and delay flowering.

Recommendations:

• Root feeding (14–20 days after transplanting): ammonium nitrate (20–25 g/10 L water) + potassium sulphate (15–20 g/10 L water) per 1 m², or use compound fertiliser with formula 20:20:20 or 15:15:15 + ME (0.2–0.3% solution). Rate – 5–8 L per 1 m². You can also use manure slurry (1:10) or poultry manure (1:20) – 2–3 L per 1 m², but only if well fermented (Tarakanov & Mukhin, 2003).

• Foliar feeding with magnesium and micronutrients (10–14 days after the root feeding) – especially important on light soils, where magnesium and iron may be deficient. Use a solution of magnesium sulphate (0.5–1%) + chelates of zinc and manganese (0.02%). This increases photosynthesis intensity and prevents chlorosis (Hochmuth & Sideman, 2023).

5.6. Feeding During Budding, Flowering, and Fruit Set

This is one of the most critical periods. The number of fruit set and future harvest depend on how fully eggplant is supplied with nutrients. During this time, reduce the nitrogen share and increase phosphorus, potassium, and boron.

Recommendations:

• Root feeding at the start of budding (1–2 weeks before mass flowering): potassium sulphate (20–25 g/10 L) + double superphosphate (10–15 g/10 L) per 1 m², or compound fertiliser with low nitrogen and high phosphorus and potassium (e.g., 10:30:20 or 12:24:12 + ME) – 0.2–0.3% solution, 5–8 L per 1 m² (Autko et al., 2012).

• Foliar feeding with boron (during budding and early flowering) – critically important for increasing fruit set. Use boric acid (0.05–0.1%, i.e., 5–10 g per 10 L water) or special boron‑containing fertilisers. Apply 1–2 times with an interval of 7–10 days, trying to wet flowers and young fruits (Hochmuth & Sideman, 2023; Rubatzky & Yamaguchi, 1997). This technique is especially effective on boron‑deficient soils and in dry weather.

• Foliar feeding with zinc and manganese (during mass flowering) promotes good pollination and ovary development. Doses as in the previous phase.

5.7. Feeding During Fruit Growth and Filling (First Wave)

During this time, the bulk of marketable fruits is formed. Plants experience maximum potassium demand, as well as calcium (to prevent blossom‑end rot) and moderate nitrogen to sustain growth.

Recommendations:

• Root feeding (at the start of active fruit growth, when ovaries reach 3–5 cm size): potassium sulphate (25–30 g/10 L) + calcium nitrate (15–20 g/10 L) per 1 m². Add a little nitrogen (ammonium nitrate – 10–15 g/10 L) if plants look green and healthy. If leaves start to lighten, increase nitrogen dose but within reasonable limits. Using calcium nitrate simultaneously supplies both nitrogen and calcium (Autko et al., 2012; Swiader & Ware, 1992).

• Foliar feeding with calcium nitrate (0.5–1% solution) during fruit filling – especially effective for preventing blossom‑end rot, as calcium through leaves reaches fruits faster. Repeat every 10–14 days when first signs of calcium deficiency appear (watery spots on fruit tip) (Hochmuth & Sideman, 2023).

• Potassium feeding (potassium sulphate) can be done as root or foliar (0.5–1% solution). Potassium improves taste and increases fruit size.

5.8. Feeding During Subsequent Fruiting Waves

Eggplant can fruit in waves until frost. After harvesting the first wave, plants often "recover" and form new ovaries. During this period, it is important to maintain balanced nutrition, but with a predominance of potassium and micronutrients.

Recommendations:

• After mass harvest of the first wave (usually 2–3 weeks after the start of fruiting), carry out a maintenance feeding with compound fertiliser high in potassium (e.g., 12:12:36 or 10:20:30 + ME) at 20–25 g/10 L per 1 m², or an equivalent set of straight fertilisers (potassium sulphate – 20–25 g, ammonium nitrate – 5–10 g, superphosphate – 10 g).

• Foliar micronutrient feedings (especially boron and zinc) are repeated when new buds and flowers appear to stimulate the next wave of fruit set.

• The interval between feedings – 10–14 days. In hot and dry weather, doses can be slightly increased (but not more than 20%), as root uptake is hindered and removal with harvest is high.

5.9. Recommended Top‑Dressing Rates (per Hectare)

For large areas and greenhouse production, it is more convenient to use hectare rates. The table below gives approximate doses for major elements in different phases (based on average recommendations, adjusted from sources). For small gardens, convert doses to area (e.g., 10 g/m² = 100 kg/ha).

Note: doses may vary depending on soil type, variety, and weather. The given norms are totals for feedings in each phase; they do not include basal application.

5.10. Practical Tips for Top‑Dressing

1. Feedings are best done in the morning or evening when evaporation is lower. In sunny weather, combine root feeding with watering to avoid root burn.

2. Solutions for feeding should be prepared immediately before use. Long storage is not allowed, as many elements may precipitate.

3. Alternating root and foliar feedings increases uptake efficiency. Root supplies the bulk, foliar quickly corrects micronutrient and calcium deficiencies.

4. Maintain an interval of 10–14 days between feedings – too frequent feedings can lead to salt buildup in the soil and poor growth.

5. Consider plant condition. If leaves are dark green and large – nitrogen is not needed yet. If lower leaves yellow – possibly nitrogen or magnesium deficiency. If fruits have a dark spot at the tip – urgently apply calcium nitrate foliar.

6. On sandy soils, the interval between feedings can be shortened to 7–10 days, and doses slightly reduced (by 10–15%), as elements leach faster and plants need more frequent replenishment.

6.1. Classification of Application Methods

All fertiliser application methods can be divided into two broad groups:

1. Root fertilisation – fertilisers are applied to the soil, into the active root zone (in dry or dissolved form). This is the main way to supply plants with macronutrients, especially nitrogen, phosphorus, and potassium.

2. Foliar (leaf) fertilisation – fertilisers in the form of aqueous solutions are applied to leaves, stems, and other above‑ground parts. This method is intended for rapid correction of micronutrient deficiencies, and for emergency delivery of macronutrients (especially calcium, magnesium, potassium) during critical growth phases.

Each of these methods has its own varieties, which we will examine in detail below.

6.2. Root Application Methods

6.3. Foliar (Leaf) Feedings

Foliar feeding is spraying plants with aqueous fertiliser solutions. This method allows quick delivery of nutrients to the parts of the plant that need them at that moment. For eggplant, foliar feedings are especially effective for:

• Correcting micronutrient deficiencies (boron, zinc, manganese, iron, molybdenum, copper) and calcium.
• Quick feeding during critical phases (budding, flowering, fruit filling).
• Supporting plants under stress (drought, waterlogging, root damage).

Advantages of foliar feeding:

• High uptake speed (through leaves, elements enter tissues within hours).
• Targeted delivery to problem areas (e.g., calcium to fruits).
• Low fertiliser consumption (doses 5–10 times lower than root feedings).
• Possibility to combine with pest and disease treatments (if compatible).

Disadvantages:

• Limited ability to apply macronutrients in large quantities (leaves cannot absorb more than a certain concentration).
• Dependence on weather conditions (spraying effective only in the absence of bright sun and wind, before or after rain).
• Risk of leaf burn if concentration is exceeded or at high temperatures.

Basic rules for foliar feeding:

1. Timing. Spray early morning (before 9–10 am) or evening (after 6–7 pm) when sun is not intense to avoid burns. On cloudy days, can be done during the day, but not in rain.

2. Solution concentrations. For eggplant, the following concentrations are recommended (by active ingredient):

• Urea (for nitrogen) – 0.5–1% (5–10 g/L).
• Potassium sulphate – 0.5–1% (5–10 g/L).
• Calcium nitrate – 0.5–1% (5–10 g/L).
• Magnesium sulphate – 0.5–1% (5–10 g/L).
• Boric acid – 0.05–0.1% (0.5–1 g/L), at early stages up to 0.2% if pronounced deficiency.
• Chelated micronutrients (Fe, Zn, Mn, Cu) – according to instructions (usually 0.01–0.05%).
• Complex water‑soluble fertilisers (20:20:20 or 10:30:20) – 0.2–0.3% (2–3 g/L).

3. Volume of working solution. For complete wetting of leaves, 300–500 L/ha (3–5 L per 100 m²) is sufficient. Abundant spraying to run‑off is not needed – fine droplet coverage is enough.

4. Adding surfactants. To improve wetting and retention of the solution on leaves, add soap (20–30 g per 10 L) or special surfactants (0.01–0.05% of volume).

5. Combining with other treatments. Foliar feeding can be combined with disease and pest treatments, but first check compatibility (do not mix alkaline and acidic formulations, Bordeaux mixture with chelates, etc.) (Hochmuth & Sideman, 2023; Autko et al., 2012).

6. Frequency. Foliar feedings are done as needed, but not more than once every 7–10 days, to avoid accumulation of elements in leaves and metabolic disturbances.

Specific foliar feeding schemes for eggplant:

• To prevent chlorosis (iron and manganese deficiency) – spray with chelates of iron and manganese (0.01–0.02% each) during active leaf growth, repeat after 10–14 days if necessary.

• To improve fruit set – spray with boric acid (0.05–0.1%) during budding and at the start of mass flowering. Repeat after 7–10 days if fruit set is weak.

• To prevent blossom‑end rot – spray with calcium nitrate (0.5–0.7%) during intensive fruit growth, every 10–14 days, especially when soil moisture is unstable.

• To maintain potassium status – spray with potassium sulphate (0.5–1%) during fruit filling, especially on light soils.

• Combined foliar feeding (e.g., solution of compound fertiliser 10:30:20 + micronutrients in chelated form) during flowering and fruit set for comprehensive nutrition.

6.4. Comparative Efficiency of Application Methods

The table below gives approximate data on the efficiency of different application methods for eggplant (based on generalised data, with specific recommendations for the crop).

Note: efficiency given for average conditions; it may vary depending on soil type, moisture, and other factors.

6.5. Recommendations for Choosing the Method for Different Conditions

For open field on medium loams (temperate climate):

• Basal application – broadcast under autumn or spring ploughing.
• Starter application – local in holes (or furrows) at planting.
• Top‑dressings – dry (inter‑row with incorporation) or liquid root, with frequency 10–14 days. Foliar – as needed (for micronutrients, calcium, boron).

For open field on light sandy soils (southern regions, arid climate):

• Basal application – definitely local (in furrows) or with controlled‑release forms (especially phosphorus and potassium).
• Top‑dressings – only liquid (root via irrigation or fertigation) with frequency 7–10 days, as elements leach quickly. Foliar feedings – essential for micronutrients and calcium.
• Drip irrigation with fertigation is recommended – the most effective method in such conditions.

For greenhouses and plastic tunnels (protected cultivation):

• Basal application – organic fertilisers and minerals (phosphorus, potassium) incorporated into soil during bed preparation.
• During the season – mainly fertigation via drip system or liquid root feedings.
• Foliar feedings – especially important for preventing calcium and micronutrient deficiencies, and for rapid correction of nutritional disorders.

For organic farming (without synthetic fertilisers):

• Basal application – manure, compost, green manures.
• Top‑dressings – manure slurries, poultry manure infusions, herbal teas, wood ash (for potassium and phosphorus), as well as foliar sprays with weak solutions of these infusions.
• Fertigation in organic systems is limited – only well‑filtered organic infusions with humic additives can be used.

6.6. Typical Mistakes in Fertiliser Application and How to Avoid Them

1. Applying fertilisers too close to the stem. This can cause burn of the root collar and roots. Always leave 10–15 cm from the stem for dry applications and mix local doses with soil.

2. Exceeding solution concentration in foliar feedings. This causes leaf burn. Always strictly follow dosages; better to use the minimum recommended concentrations.

3. Applying fertilisers to dry soil without subsequent watering. Leads to slow action and possible root burn. Always water after dry fertiliser application, or combine with rain/irrigation.

4. Mixing incompatible products in one tank. Can cause precipitation and reduced efficiency. Check compatibility or consult specialists before mixing.

5. Ignoring weather conditions. In hot weather, foliar feedings should be done only in the morning or evening; root feedings after watering. In cool weather (below 15 °C), phosphorus and micronutrient uptake slows, so apply them in more available forms (chelates, phosphites) or warm the solution to 20–22 °C.

7.1. Influence of Soil Type on Eggplant Nutrition

7.2. Nutritional Specifics in Protected Cultivation (Greenhouses and Tunnels)

In greenhouses, eggplant nutrition conditions have several peculiarities compared to open field. They are related to limited soil volume, absence of natural precipitation, more intensive fruiting, and higher temperature.

Main differences in greenhouse nutrition:

1. Intensive fruiting and high nutrient removal. In greenhouses, eggplant yield is often 1.5–2 times higher than in open field (Autko et al., 2012). Accordingly, nutrient consumption increases, especially potassium. Therefore, total fertiliser rates (especially potassium and phosphorus) should be increased by 20–30% compared to open field.

2. Fertigation as the main method. In modern greenhouses, eggplant is almost always grown with drip irrigation and fertigation. This allows precise dosing, maintaining optimal moisture, and avoiding soil salinisation (Hochmuth & Sideman, 2023; Autko et al., 2012). All top‑dressings are applied through the drip system.

3. Increased calcium requirement. In greenhouses, due to high temperature and intensive transpiration, calcium transport to fruits may be disrupted, provoking blossom‑end rot. Therefore, calcium nitrate is included in the fertigation solution regularly (in each feeding, at low dose) and/or foliar sprays (0.5–0.7%) are applied (Hochmuth & Sideman, 2023).

4. High micronutrient demand. In protected cultivation, due to limited soil volume and intensive use, micronutrient reserves are quickly depleted. Regular (every 10–14 days) foliar sprays with chelates of zinc, manganese, iron, boron are obligatory, especially during flowering and fruiting (Autko et al., 2012).

5. Salinity control. With fertigation, it is important to regularly (every 2–3 weeks) irrigate with clean water to leach excess salts from the root zone. Electrical conductivity of the soil solution should not exceed 2.0–2.5 mS/cm (for eggplant this is higher than for tomato, but still critical) (Hochmuth & Sideman, 2023).

6. Greenhouse fertigation schedule: Start 7–10 days after transplanting with a dose of 0.5–0.7 g/L of compound fertiliser. During active growth and flowering, increase concentration to 1–1.2 g/L; during fruiting – to 1.2–1.5 g/L with an emphasis on potassium. Irrigate daily or every other day, but with low‑concentration solutions (0.1–0.2% N) for uniform nutrition.

Recommended N : P₂O₅ : K₂O ratios for greenhouse eggplant fertigation (by phases):

• Active growth: 1 : 0.5 : 1.2 (e.g., 20:10:25 + ME).
• Flowering and fruit set: 1 : 0.8 : 1.8 (e.g., 15:12:30 + ME).
• Fruiting: 1 : 0.5 : 2.5 (e.g., 10:5:35 + ME) with calcium nitrate added separately (for calcium).

7.3. Nutritional Specifics in Arid Regions (Southern Zones, without Irrigation)

In regions with insufficient rainfall and high temperatures, eggplant often experiences moisture deficit, which sharply reduces availability of nutrients, especially phosphorus and potassium (Swiader & Ware, 1992; Autko et al., 2012).

Main problems and solutions:

• Reduced phosphorus availability. In dry soil, phosphorus is immobile; roots cannot absorb it. Therefore, phosphorus fertilisers are applied locally (in holes or furrows) and in readily soluble forms (double superphosphate, ammonium phosphate). Starter solutions of potassium monophosphate at watering are also effective.
• Increased potassium requirement. Potassium increases drought resistance. In arid zones, potassium rate is increased by 30–40% compared to average norms, preferring sulphate forms (potassium sulphate, K‑Mg sulphate).
• Emphasis on foliar feedings. Under drought, root nutrition is hindered, so micronutrients and part of macronutrients (potassium, magnesium, calcium) are applied through leaves to bypass root uptake limitations.
• Soil moisture conservation. Mulching (straw, manure, agro‑textile) helps reduce evaporation and maintain moisture, improving nutrient uptake. Mulch also protects roots from overheating (Autko et al., 2012).

Recommendations for nutrition regime in arid conditions:

• Basal fertiliser application (especially phosphorus and potassium) is done deep (20–25 cm) so roots can reach them in more humid layers.
• Liquid fertilisers should be combined with irrigation (if available), otherwise their efficiency drops sharply.
• Micronutrients (boron, zinc, manganese) must be applied foliarly during budding and flowering.

7.4. Nutritional Specifics in Cold and Humid Climates (Northern Zones)

In conditions of cool summers and short growing seasons, the main nutritional problems for eggplant are related to slow root growth and low phosphorus availability (at soil temperatures below 15 °C, phosphorus uptake drops by 50–75%) (Autko et al., 2012; Rubatzky & Yamaguchi, 1997).

Main approaches:

• Starter phosphorus priority. Before planting, apply readily soluble phosphorus fertilisers (potassium monophosphate, ammonium phosphate, double superphosphate) in holes to stimulate root formation.
• Reduced nitrogen feedings early in growth. In cold soil, nitrogen is absorbed slowly; excess can accumulate as nitrates and inhibit growth. Apply nitrogen only in nitrate form (calcium nitrate, sodium nitrate), which is more easily absorbed at low temperatures.
• Use warm water for irrigation and feeding. Water for solutions should have a temperature of 20–22 °C to avoid cooling the soil and stimulate root activity.
• Foliar feedings. In cold weather, foliar treatments (especially micronutrients) become the main way of rapid nutrition, as root uptake is limited.
• Growing on ridges. In northern regions, it is recommended to plant eggplant on raised beds, which warm up better, improving phosphorus and potassium uptake.

7.5. Effect of Mulching on Nutrition

Mulching is an effective agronomic practice that affects not only soil moisture and temperature, but also nutrient availability.

Organic mulch (straw, manure, grass clippings, compost):

• Retains moisture, prevents root overheating.
• As it decomposes, gradually releases nutrients (especially nitrogen, potassium, micronutrients), reducing the need for mineral top‑dressings.
• Reduces nitrogen leaching on light soils.
• However, high‑carbon mulch (straw, sawdust) may temporarily immobilise nitrogen during decomposition, so it is better to apply it in autumn or add nitrogen fertilisers in spring (Hochmuth & Sideman, 2023; Autko et al., 2012).

Black plastic mulch (or agro‑fabric):

• Used in the south and in greenhouses to accelerate soil warming and conserve moisture.
• Limits natural precipitation, so all feedings must be done through drip irrigation or liquid solutions in holes.
• Requires more frequent application of water‑soluble fertilisers, as organic matter does not decompose under the mulch.

Recommendations: when using organic mulch, reduce nitrogen top‑dressing rates by 15–20%, especially in the second half of the season. When using black film, обязательно use fertigation or liquid root feedings every 7–10 days.

7.6. Nutritional Specifics with Different Irrigation Methods

• Drip irrigation (fertigation) – the best method for precise nutrition, as described above. Allows split doses, reduce losses, and adapt nutrition to growth phases.
• Sprinkler irrigation (surface watering) – less effective for nutrition, as fertilisers may be washed off leaves and sprayed unevenly. With sprinkling, it is better to use dry top‑dressings in inter‑rows or foliar treatments before or after watering (Hochmuth & Sideman, 2023).
• Furrow irrigation – with this method, fertilisers are applied either dry (in inter‑rows followed by incorporation and watering) or as liquid solutions through irrigation furrows (starter and top‑dressing). Efficiency is lower than fertigation but higher than broadcast.

7.7. Summary of Nutrition Adaptation to Growing Conditions

8.1. General Principles of Diagnosis

Before moving on to specific symptoms, it is important to understand several general rules for diagnosing nutritional disorders:

1. Localisation of symptoms. Deficiency of mobile elements (nitrogen, phosphorus, potassium, magnesium) primarily appears on old (lower) leaves, as the plant mobilises these elements from old tissues and directs them to young, actively growing parts. Deficiency of immobile elements (calcium, iron, boron, copper, manganese, zinc, sulfur) appears on young (upper) leaves and growing points, as these elements cannot be redistributed from old tissues (Hochmuth & Sideman, 2023; Autko et al., 2012).

2. Character of yellowing. Chlorosis (yellowing) may be uniform (over the whole leaf) or interveinal (veins remain green, tissue between them yellows). Uniform chlorosis often indicates nitrogen or sulfur deficiency. Interveinal chlorosis – deficiency of magnesium, iron, manganese, or zinc.

3. Speed of symptom appearance. Acute deficiencies (with sharp shortage of an element) appear quickly – within days. Chronic deficiencies develop gradually over weeks. This helps distinguish them from diseases or mechanical damage.

4. Exclude other factors. Similar symptoms can be caused by diseases, pests, waterlogging or drought, root damage. Therefore, it is important to assess plant condition comprehensively and check soil moisture, pH, and pest presence.

5. Use laboratory analysis. Visual diagnosis is only the first step. For accurate confirmation and adjustment of fertilisation, agrochemical soil analysis and leaf diagnostics (element content in dry leaf matter) are recommended (Hochmuth & Sideman, 2023; Rubatzky & Yamaguchi, 1997).

8.2. Macronutrient Deficiencies

8.3. Secondary Nutrient Deficiencies

8.4. Micronutrient Deficiencies

8.5. Differential Diagnosis: How to Distinguish Deficiency from Diseases and Other Problems

Many deficiency symptoms resemble disease or pest damage. Here are key differences:

Important: when suspecting deficiency, always check soil moisture and pH. Often, symptoms resembling deficiency arise from water regime or pH issues, not from lack of elements in soil (Hochmuth & Sideman, 2023).

8.6. Summary Table of Deficiency and Excess Symptoms in Eggplant

8.7. Practical Recommendations for Diagnosis and Correction

1. Regularly inspect plants (at least once a week) and note any changes in colour, leaf shape, and fruits.

2. Keep a feeding diary – record when, with what, and in what doses you fertilised. This helps determine the cause of problems faster.

3. When symptoms appear, first check:

• Soil moisture (at 10–15 cm depth) – is it dry or waterlogged.
• Soil pH (using pH paper or meter) – if pH outside 6.0–6.8, correct it.
• Presence of pests and diseases (look at leaf undersides, stems, root collar).

4. If symptoms indicate deficiency, start with foliar feeding of the relevant element (at low concentration) – this is the fastest way. Apply root feeding after 2–3 days if foliar did not work.

5. Do not mix several micronutrients in one tank without checking compatibility, especially chelates with sulphates (they may precipitate). It is better to apply treatments separately or use ready‑made compound micronutrient fertilisers (Hochmuth & Sideman, 2023).

6. In case of element excess, stop its application and try to leach excess with irrigation (on light soils) or add organic matter to bind it.

7. Do not try to treat "all deficiencies at once" – this often leads to excess. Diagnose the specific problem and act purposefully.

9.1. Mistakes in Fertiliser Selection

9.2. Mistakes in Timing and Dosages

9.3. Mistakes in Application Methods

9.4. Mistakes Related to Soil Condition

9.5. Mistakes in Diagnosis and Correction

9.6. Table of Typical Mistakes and Their Prevention

9.7. General Recommendations for Preventing Mistakes

1. Plan the nutrition system in advance – based on soil analysis, planned yield, and growth phases. This reduces the likelihood of spontaneous decisions.

2. Keep a feeding diary – record dates, compositions, doses, and plant condition. This helps analyse mistakes and adjust strategy in future (Hochmuth & Sideman, 2023).

3. Start with small doses – when using new fertilisers or foliar feedings, first apply the minimum recommended concentration and observe plant response.

4. Learn to diagnose – regularly inspect plants, compare with descriptions of deficiencies. Use keys (see chapter 8).

5. Combine methods – combine root and foliar feedings, dry and liquid forms, organic and mineral fertilisers for best results.

6. Do not rely only on intuition – if possible, conduct agrochemical soil and leaf analysis. This is the most reliable way to avoid mistakes.

10.1. General Nutrition Scheme by Growth Phases (Summary Table)

Below is a summary table that brings together all growth phases, feeding objectives, recommended fertiliser compositions, and application methods.

10.2. Nutrient Application Rates for Major Elements by Phase (kg/ha of active ingredient)

This table gives the total amount of each element recommended to apply in specific phases (per hectare). To convert to per 100 m², divide by 100.

Note: doses are totals for all feedings in that phase and do not include basal application. For micronutrients (boron), doses are in grams per hectare.

10.3. Nutrient Ratios by Growth Phase

For quick reference on element proportions in different periods, use this table with recommended N : P₂O₅ : K₂O ratios.

Note: these ratios reflect nutrition priorities in each phase. Actual fertilisers may have slight deviations, but the overall trend should be followed.

10.4. Fertiliser Calculator for Feedings (Simple Conversion)

Often fertiliser packaging gives dosages in grams per 10 litres of water. Below is a table for quick calculation of simple fertiliser amounts for preparing a standard bucket (10 L) of working solution for root feeding.

Example: for feeding in active growth phase (see table 10.1, item 5) you need to prepare solution per 1 m²: ammonium nitrate 20 g + potassium sulphate 15 g per 10 L water. From the table above, this corresponds to 20 g ammonium nitrate and 15 g potassium sulphate per 10 L water, which is exactly the dose for watering 1 m².

10.5. Fertigation Schedule for Eggplant (Drip Irrigation)

With fertigation, fertilisers are applied with each irrigation at low concentrations. This is the most efficient nutrition system, especially on light soils and in greenhouses. Below is an approximate fertigation schedule for eggplant using water‑soluble fertilisers.

General rules for fertigation:

• Working solution concentration – 0.05–0.15% (0.5–1.5 g fertiliser per 1 L water).
• Irrigate daily or every other day, depending on weather.
• At the start of irrigation – clean water (10–15 minutes), then fertiliser application, at the end – clean water again to flush the system.
• Adjust irrigation rate and fertiliser amount according to growth phase and weather.

Note: these figures are approximate. To convert to grams of fertiliser per 1 m², use the element content in the fertiliser (e.g., calcium nitrate – 15% N, so to get 0.1 g N per 1 m² you need 0.1 / 0.15 = 0.67 g fertiliser per 1 m²).

Example: For active growth phase with irrigation rate 1.5 L/m² and desired N concentration = 100 mg/L (0.1 g/L), you need to supply 0.15 g N per 1 m². If using calcium nitrate (15% N), you need 0.15 / 0.15 = 1 g per 1 m². Dissolve this dose in 1.5 L water (irrigation rate) and apply via fertigation.

10.6. Quick‑Reference Table: What to Do in Case of Deficiency

This table helps quickly orient when the first signs of deficiency appear in eggplant.

10.7. How to Adapt Schemes to Your Conditions (Checklist)

Before applying any of the above schemes, complete this checklist to adapt to your conditions:

1. Determine soil type. Sandy, loamy, peat? Doses and frequency of feedings depend on this (see chapter 7).

2. Check soil pH (with pH paper or meter). Optimal 6.0–6.8. If deviations – correct (liming or acidification).

3. Assess fertility. Was organic fertiliser applied in autumn? What was the predecessor? This affects starter nitrogen rates.

4. Consider weather. In heat and drought – increase irrigation frequency and fertigation, reduce solution concentration. In cool weather – use nitrate forms of nitrogen and phosphorus feedings in available forms (potassium monophosphate).

5. Observe plants. Regularly (weekly) inspect leaves and fruits for deficiency or excess symptoms (see chapter 8). Adjust feedings accordingly.

6. Keep records. Record what and when you applied, and how plants responded. This helps optimise the scheme for next season.