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Comprehensive Analysis of NPK (Nitrogen, Phosphorus, Potassium) Absorption (g/m²) at Each Growth Stage of Bell Pepper (Capsicum annuum)
Overview
In bell pepper (Capsicum annuum) cultivation, proper application of NPK (nitrogen, phosphorus, potassium) fertilizers is key to improving yield and quality. However, quantitative data on actual NPK absorption (g/m²) at each growth stage (germination, seedling, vegetative growth, flowering, fruit set/enlargement, and maturation/coloring) is limited both in Japan and internationally. This report systematically compiles estimation methods for stage-specific absorption amounts, their rationale, and practical considerations based on Japanese and international literature, experiments, model data, and government sources, providing in-depth understanding and practical guidelines for field application.
1. Fundamental Data on NPK Absorption Throughout the Entire Bell Pepper Growing Period
Reference Values for Total Absorption (g/m²)
In standard Japanese bell pepper cultivation, the approximate NPK absorption per yield unit (1,000 kg/10a; 1,000 kg/1,000 m², i.e., 1 kg/m²) is as follows [1]:
- Nitrogen (N): 3.0–5.2 g/m²
- Phosphorus (P): 0.6–1.1 g/m²
- Potassium (K): 5.0–6.5 g/m²
These are average absorption values at economically viable yield levels and are consistent with values indicated by Japanese agricultural guidance organizations and fertilization standards [2][3].
2. Growth Stage Classification and Duration
Definition and Characteristics of Growth Stages
Typical growth stages of bell pepper can be classified as follows [2][3][8]:
- Germination stage (sowing to immediately after germination): 2–7 days
- Seedling stage (after germination to true leaf development/transplanting): 20–40 days
- Vegetative growth stage (transplanting to first flowering): 20–30 days
- Flowering stage (first flowering to beginning of fruit set): 10–15 days
- Fruit set/enlargement stage (fruit set to fruit enlargement/beginning of harvest): 30–50 days
- Maturation/coloring stage (late harvest to coloring/maturation): 20–30 days
Actual durations vary depending on cultivar and growing conditions, but these serve as standard guidelines.
3. Estimation Methods and Distribution Ratios of NPK Absorption by Growth Stage
Limitations of Direct Data and Estimation Approaches
In Japanese public data and experimental records, systematically published absorption data by developmental stage is extremely scarce; values must mainly be back-calculated from seasonal totals and split-application ratios [3][4]. Therefore, the following estimation methods are effective.
3.1 Estimation Method Based on Total Absorption
- Procedure:
- Use the target yield and total NPK absorption per unit area (see above) as the baseline
- Multiply by the biomass accumulation rate for each growth stage, differentiation progress, and ratios from international absorption ratio models (see table below) to estimate absorption at each stage [13][19][8]
3.2 Distribution Ratios (Recommended Values from International Models and Previous Studies)
According to multiple domestic and international publications and simulations [13][8][19], the approximate NPK absorption ratios by growth stage are as follows.
| Growth Stage | Absorption Ratio (%) | Notes |
|---|---|---|
| Germination | 0–2 | Very minimal |
| Seedling | 5–10 | Low nutrient absorption capacity |
| Vegetative growth (transplanting to flowering) | 20–25 | Rapid plant growth |
| Flowering | 15–20 | Growth + reproductive transition |
| Fruit set/enlargement | 30–40 | Highest absorption |
| Maturation/coloring | 10–20 | Quality formation |
While N/P/K show similar trends, potassium absorption is particularly high during the fruit set/enlargement stage, and phosphorus tends to be absorbed more intensively from the vegetative growth to flowering stages.
4. Specific Estimated Absorption Values (g/m²) — Standard Case
Sample Calculation (for a yield of 1,000 kg/1,000 m²)
Based on the standard Japanese yield of 1,000 kg/1,000 m² and total absorption values, the estimated absorption at each stage is as follows. Distribution ratios are based on the average model values described above, applying the same ratio for N, P, and K.
| Stage | N (g/m²) | P (g/m²) | K (g/m²) |
|---|---|---|---|
| 1. Germination (2%) | 0.10 | 0.02 | 0.13 |
| 2. Seedling (8%) | 0.40 | 0.07 | 0.52 |
| 3. Vegetative growth (22%) | 1.10 | 0.22 | 1.43 |
| 4. Flowering (18%) | 0.90 | 0.16 | 1.17 |
| 5. Fruit set/enlargement (35%) | 1.75 | 0.33 | 2.34 |
| 6. Maturation/coloring (15%) | 0.75 | 0.13 | 0.98 |
| Total | 5.0 | 0.93 | 6.57 |
* Based on N = 5 g/m², P = 0.93 g/m², K = 6.57 g/m². Distribution ratio example: 2%/8%/22%/18%/35%/15%
* The absorption pattern remains the same even when calculated using the lower and upper bounds.
Notes
- In the early seedling stage, root mass and leaf area are small, limiting absorption capacity
- Absorption increases dramatically during vegetative growth, flowering, and fruit enlargement (especially N and K)
- Phosphorus is actively absorbed from the early stages through the reproductive transition, affecting fruit set count and flower bud formation
- During the maturation stage, potassium contributes to fruit quality and coloring
5. Supplementary Information and Practical Considerations
- Actual absorption varies depending on region, cultivar, cropping system, and weather conditions. These are approximate values only [2][5]
- In Japanese fertilization practices, split applications and top-dressing to concentrate nutrient effectiveness at critical stages are generally recommended [3][2]
- Field diagnosis, soil analysis, and leaf analysis are extremely important for enhancing practical adaptability [2][4][5]
- Excessive nitrogen application or late-season top-dressing can cause deterioration of fruit quality, disease induction, and material waste [3][5][22]
- Absorption dynamics and optimization strategies differ for distinctive cropping systems such as organic farming and greenhouse cultivation [7][3]
6. References: Key Literature and Models for Estimation and Distribution
- Japanese government sources and fertilization guidelines (MAFF, prefectural guidance manuals) [3][4][5]
- International absorption modeling studies and split-application design literature [13][8][19]
- Estimation methods based on yield, biomass accumulation, and dry matter weight ratios by growth stage [13][19]
- International knowledge on cultivation management strategies and top-dressing timing design based on absorption patterns [8][13][14]
Summary
Although direct data on NPK absorption (g/m²) at each growth stage of bell pepper is scarce both in Japan and internationally, logical estimation based on yield benchmarks, biomass accumulation data, model distributions, and fertilization guidance reveals that absorption is very low in the early stages, increases sharply from the vegetative growth stage through flowering and fruit enlargement, and strongly contributes to fruit quality formation during the maturation stage. It is recommended to apply these findings to region- and cultivar-specific diagnostics and fertilization planning in the field.
Sources
[1] 完璧なBell pepperを育てるには？ヒントをいくつかご紹介します！: https://www.goldenefertilizer.com/ja/news/how-to-grow-the-perfect-green-pepper-some-tips-to-share-with-you/
[2] 「Bell pepper」栽培のポイント - みらい蔵: https://mirai-zou.co.jp/advice/62/
[3] 4．作物の栄養生理と養分吸収 - MAFF: https://www.maff.go.jp/j/seisan/kankyo/hozen_type/h_sehi_kizyun/pdf/gum12.pdf
[4] 第2部 果菜類の有機栽培の基本・共通技術 - 日本土壌協会: https://www.japan-soil.net/report/h25tebiki_02.pdf
[5] 土壌肥料対策指針 - 和歌山県: https://www.pref.wakayama.lg.jp/prefg/072000/ecofamar/shishin/d00216389_d/fil/shishinzenbun.pdf
[7] Organic Fertilizer Optimization for Enhanced Growth and Nutrient ...: https://www.mdpi.com/2311-7524/11/9/1066
[8] Crop Guide: Nutrients for Pepper - Haifa Group: https://www.haifa-group.com/articles/crop-guide-nutrients-pepper
[13] Growth stage wise fertigation scheduling improves nutrient uptake ...: https://www.tandfonline.com/doi/abs/10.1080/01904167.2020.1862194
[14] nutrition of the hot pepper crop - FAO: https://www.fao.org/4/y5259e/y5259e07.htm
[19] Modelling Nutrient Uptake of Sweet Pepper - ResearchGate: https://www.researchgate.net/publication/40094508_Modelling_Nutrient_Uptake_of_Sweet_Pepper
[22] Growth and Yield Responses of Sweet Pepper (Capsicum annum L ...: https://jpp.journals.ekb.eg/article_35501_ba9a11dfdd2dd82e39d5005669c3a32a.pdf