Comprehensive Report on NPK (Nitrogen, Phosphorus, Potassium) Absorption by Growth Stage for Tomato (g/m²)

Overview

This report presents the latest comprehensive findings and necessary estimated values for NPK (nitrogen, phosphorus, potassium) absorption (g/m²) at each growth stage of tomato (① germination/seedling, ② vegetative growth, ③ flowering/fruit set (reproductive), ④ fruit enlargement/maturation), based on scientific literature, government guidelines, and agricultural extension materials from both Japan and international sources. Where direct absorption data is unavailable, logical estimation methods based on yield and growing days are clearly stated along with their rationale and assumptions.

1. Fundamental Total NPK Absorption of Tomato over the Entire Growth Period

The approximate absorption per ton of tomato is as follows:

• Nitrogen (N): 2 kg
• Phosphorus (P₂O₅): 0.6 kg
• Potassium (K₂O): 4 kg

The average yield of greenhouse and open-field tomato cultivation in Japan is 6–10 kg/m² (60–100 t/ha). Based on this, the total NPK absorption over the entire growing period of tomato is as follows [1][2][3][4]:

• Nitrogen (N): 12–20 g/m²
• Phosphorus (P₂O₅ equivalent): 3.6–6 g/m²
• Potassium (K₂O equivalent): 24–40 g/m²

These values are broadly consistent with figures from Japanese agricultural extension materials, research papers, and major international fertilization guidelines.

2. NPK Absorption Patterns by Growth Stage

NPK absorption in tomato varies significantly by growth stage. Below is a summary of the characteristics, absorption allocation, and proportional ratios for each stage.

2.1 Germination/Seedling Stage

• Period: From sowing to true leaf development/transplanting
• Estimated total absorption: Less than 5–10% of total
• Reason: The plant is small at this stage, and nutrient absorption required for tissue formation is minimal. Excessive fertilization poses risks such as root damage.
• Estimated values (based on a 10 kg/m² yield model):
  • N: 1–2 g/m²
  • P: 0.3–0.6 g/m²
  • K: 2–4 g/m²

2.2 Vegetative Growth Stage

• Period: From transplanting to initial flower bud formation
• Estimated total absorption: 20–30% of total
• Reason: Active elongation of stems, leaves, and root systems builds the foundation for photosynthetic capacity and reproductive growth. N and K absorption accelerate as root development progresses.
• Estimated values:
  • N: 3–6 g/m²
  • P: 1–1.8 g/m²
  • K: 5–12 g/m²

2.3 Flowering/Fruit Set (Reproductive Stage)

• Period: From bud formation to flowering and initial fruit set (including pinching)
• Estimated total absorption: 30–40% of total (N and K); P is also relatively high
• Reason: With the development of flowers and fruit, the absorption rate of N, P, and K increases further. K in particular surges during fruit set and truss enlargement. The NPK balance shifts slightly toward K.
• Estimated values:
  • N: 6–8 g/m²
  • P: 1.5–2.4 g/m²
  • K: 9–14 g/m²

2.4 Fruit Enlargement/Maturation Stage

• Period: From initial fruit expansion to harvest/final ripening
• Estimated total absorption: 40–60% of total (N and K); P absorption decreases somewhat
• Reason: High K absorption continues for fruit enlargement, sugar content improvement, and quality stabilization. Excess N can cause excessive vegetative growth and quality deterioration, so appropriate quantity management is important.
• Estimated values:
  • N: 8–12 g/m²
  • P: 2.2–3.5 g/m²
  • K: 14–20 g/m²

3. Estimation Methods and Rationale

• The above values are based on yield-corresponding absorption data (g/m²) from Japan and international sources, with each stage's absorption ratios (5–10%, 20–30%, 30–40%, 40–60%) applied cumulatively.
• The absorption ratios are based primarily on the following factors [2][4][5][6][7]:
  • Absorption concentration trends after truss formation documented in domestic and international agricultural extension materials and papers
  • Fertilization split records from actual cultivation (basal/topdressing ratios and timing)
  • Empirical data showing absorption rate transitions between stages
• Phosphorus absorption peaks during the vegetative growth to early flowering stage, then plateaus somewhat, but a certain amount is still required for basal metabolism during the fruiting stage [3][4].
• Potassium absorption remains at a high level continuously from flowering through fruit enlargement and maturation.
• While minor differences exist due to plant spacing, planting density, and management systems, the above ratios are applicable to both greenhouse and open-field cultivation under general conditions.

4. Variation by Cultivar and Environmental Factors

• Notable differences in absorption allocation by cultivar are generally not significant except for long-term cultivation or specialized lines [1][4][7].
• Environmental conditions (temperature, irrigation, nutrient management) cause some variation in total absorption, but the relative allocation by growth stage remains consistent.
• Therefore, while fine-tuning fertilization to individual conditions is optimal, the general estimated values presented here are sufficiently reliable.

5. Summary Table: NPK Absorption by Growth Stage (g/m², 10 kg/m² Yield Model)

Growth Stage	N (g/m²)	P (g/m²)	K (g/m²)
Germination/Seedling	1–2	0.3–0.6	2–4
Vegetative Growth	3–6	1–1.8	5–12
Flowering/Fruit Set (Reproductive)	6–8	1.5–2.4	9–14
Fruit Enlargement/Maturation	8–12	2.2–3.5	14–20

* Each value assumes standard yield and planting density.

6. Reference: Application to Fertilization Planning and Field Management

• These can be directly linked to actual fertilization programs, including pinching and topdressing schedules at each phase.
• The amount of K topdressing from the fruit enlargement stage onward is closely related to quality management (lycopene content, sugar content maintenance, blossom-end rot reduction, etc.).
• To prevent the risk of excessive vegetative growth and fruit quality deterioration from excess N, quantitative management according to growth stage is essential.

7. Conclusion

NPK absorption in tomato exhibits distinct peaks and shifts at each growth stage. The estimated values and allocation ratios compiled in this report integrate major scientific and agronomic evidence from multiple primary sources in both Japanese and English, and can serve as a baseline for practical fertilization planning and crop management.

---

Sources

[1] Tomatoの施肥｜養分吸収の特性から成長ステージごとの施肥調整まで: https://www.zero-agri.jp/guide/fertilization-for-tomato/
[2] Absorption of Nutrient Ions by the Tomato Plant at Various Stages of Development: https://scholarworks.uni.edu/cgi/viewcontent.cgi?article=2894&context=pias
[3] Evaluation of the Nutrients Uptake by Tomato Plants in Different Phenological Stages Using an Electrical Conductivity Technique: https://www.mdpi.com/2077-0472/11/4/292
[4] TOMATO - CA.gov (Nitrogen Fertilizer Management for Processing Tomatoes): https://apps1.cdfa.ca.gov/FertilizerResearch/docs/TomatoBrochure.pdf
[5] N and K for Tomato Production - e-GRO: https://e-gro.org/pdf/E809.pdf
[6] 促成Tomatoの養液土耕栽培における窒素施肥量削減: https://www.pref.ibaraki.jp/nourinsuisan/enken/seika/yasai/tomato/documents/s1711.pdf
[7] 第1章 緒 論 - 北海道立総合研究機構: https://www.hro.or.jp/upload/14994/139.pdf
[8] Tomato養液栽培における施肥の量的管理法: https://www.kankyou-marc.jp/fukyuu/pdf/820228.pdf