Article Information
- Title: 유럽표준분석법과 농진청 표준분석법에 의한 원예용 상토의 물리성 비교분석
- Authors: 이현행, 김계훈, 하상건, & 강지영
- Published: 2006
- Journal: 한국토양비료학회지 (Korean Journal of Soil Science and Fertilizer)
- Volume: 39
- Issue: 2
- Pages: 116-122
- KCI: https://www.kci.go.kr/kciportal/ci/sereArticleSearch/ciSereArtiView.kci?sereArticleSearchBean.artiId=ART001124532
Research Background
A. Research Context
- Growing Media Importance: Horticultural substrates (growing media) are critical for plug seedling production, enabling high-density cultivation and automation in horticulture.
- Global Practices: Organic materials (e.g., peat moss, coir dust) and inorganic materials (e.g., perlite, vermiculite) are widely used, often blended to optimize physical and chemical properties for plant growth.
- Standardization Needs: Varied analysis methods across countries complicate comparisons of substrate quality, leading to disputes between manufacturers and users.
B. Knowledge Gap
- Methodological Discrepancies: Prior to this study, Korea’s Rural Development Administration (RDA) and the European Committee for Standardization (CEN) had distinct methods for analyzing substrate properties, yielding incompatible results.
- Lack of Cross-Validation: No systematic comparison existed between RDA and CEN methods, hindering international collaboration and quality benchmarking.
C. Research Objectives
- Compare physical properties (bulk density, particle density, porosity, water/air volume, available water) of horticultural substrates analyzed by CEN and RDA methods.
- Establish correlation models to convert results between the two standards.
D. Significance
- Harmonization: Facilitates global trade and research by enabling data comparison between Korean and European substrates.
- Practical Resolution: Helps resolve conflicts between substrate producers and users by providing validated conversion metrics.
E. Additional Context
- CEN Methods: Developed in 1999 by 19 European nations to unify substrate analysis protocols.
- RDA Methods: Introduced in 2002 to standardize Korea’s growing media industry, tailored to local materials like coir dust and rice hulls.
- Key Properties: Porosity and air/water volume directly impact plant growth, but measurement inconsistencies persist due to methodological differences (e.g., drying protocols, container dimensions).
Materials and Methods
1. Sample Collection & Preparation
- Samples:
- 40 commercial substrates (vegetable seedling production)
- 10 raw materials (organic: peat moss, coir dust, rice hull; inorganic: perlite, vermiculite, zeolite)
- Processing: Sieved through 5 mm mesh to ensure uniformity.
2. Analytical Methods
- CEN Methods (European Standard)
- Bulk Density: Measured using 100 mm diameter × 50 mm height cylinders after saturation and drying.
- Particle Density: Calculated from organic matter/ash content (450°C combustion).
- Porosity/Water/Air Volume:
- Saturated samples drained at -1 kPa (sand suction table).
- Volumes derived from weight differences.
- RDA Methods (Korean Standard)
- Bulk Density: 74 mm diameter × 25 mm height cylinders + 500g plunger compression.
- Particle Density: Helium pycnometry (Micromeritics, USA).
- Porosity/Water/Air Volume:
- Samples oven-dried at 105°C before saturation.
- Drained at -1 kPa/-5 kPa for water retention metrics.
3. Key Experimental Differences
| Parameter | CEN Method | RDA Method |
|---|---|---|
| Container | 100 mm diameter × 50 mm height | 74 mm diameter × 25 mm height |
| Drying | Air-dried | Oven-dried (105°C, 16 hrs) |
| Particle Density | Organic matter combustion | Helium gas displacement |
| Drainage | 48 hrs at -1 kPa | 24 hrs at -1 kPa |
4. Statistical Analysis
- Correlation: Linear regression (R²) between CEN and RDA results.
- Significance: p < 0.01 (ANOVA).
Key Notes on Methodology
- Precision Focus: CEN prioritized natural state measurements, while RDA emphasized controlled drying for reproducibility.
- Real-World Relevance: Commercial substrates tested reflect actual agricultural use in Korea/EU.
- Limitations:
- Water/air volume showed poor correlation due to methodological divergence.
- Smaller RDA containers may underrepresent heterogeneity.
Results & Discussions
1. High Correlation for Density & Porosity
- Bulk Density: Strong linear relationship (R² = 0.8304, *p* < 0.01).
- CEN values (0.11–0.33 g cm⁻³) consistently higher than RDA (0.07–0.23 g cm⁻³) due to container size effects.
- Particle Density: Significant correlation (R² = 0.8136, *p* < 0.01).
- CEN (1.6–2.7 g cm⁻³) vs. RDA (1.0–2.4 g cm⁻³); differences attributed to combustion vs. helium methods.
- Porosity: Moderate agreement (R² = 0.6374, *p* < 0.01).
- Both methods aligned for total pore space (CEN: 85–94%; RDA: 88–95%).
2. Low Agreement for Hydraulic Properties
- Water Volume: Weak correlation (R² = 0.2692).
- CEN measured higher (52–86%) vs. RDA (20–63%) due to drying protocols.
- Air Volume: Minimal relationship (R² = 0.0739).
- RDA reported wider ranges (30–75%) vs. CEN (5–38%).
- Available Water: Poor alignment (R² = 0.3327).
- CEN values (57–71%) exceeded RDA (1–35%) from drainage time/suction pressure differences.
3. Discussion Points
- 1. Methodological Impacts
- Container Geometry: Larger CEN cylinders better captured bulk heterogeneity, while RDA’s smaller size increased compaction artifacts.
- Drying Artifacts: RDA’s oven-drying shrank pores, reducing measured water/air volumes versus CEN’s air-dried samples.
- 2. Practical Implications
- Density/Porosity: Results convertible between methods for substrate screening.
- Hydraulic Properties: Require method-specific thresholds (e.g., RDA’s lower air volume may still indicate adequate aeration).
- 3. Limitations & Future Work
- Standardization Gap: Harmonize drainage protocols (e.g., equalize suction durations).
- Material-Specific Bias: Test correlations for peat-free substrates (rising sustainability demand).
Conclusions
1. Method-Specific Consistency
- Bulk density, particle density, and porosity showed strong correlations (R² > 0.63) between CEN and RDA methods, enabling cross-method data conversion for these parameters.
- Hydraulic properties (water/air volume, available water) exhibited poor agreement (R² < 0.34), highlighting protocol-dependent variability.
2. Practical Recommendations
- For density/porosity: Use either method interchangeably with conversion factors.
- For water/air metrics: Apply method-specific thresholds (e.g., RDA’s lower water volumes ≠ poor quality).
3. Standardization Needs
Container size and drying protocols are critical variables requiring harmonization for reliable hydraulic property comparisons.
4. Final Statement
This study confirms that while CEN and RDA methods yield comparable results for basic physical properties, their divergent approaches to hydraulic measurements necessitate careful method selection based on application needs. Future efforts should focus on aligning experimental protocols—particularly for water-related metrics—to enhance global interoperability in substrate quality assessment.