RB209
RB209, or the Nutrient Management Guide, is a guide that provides best practices for applying fertilizers and organic materials to crops and grassland in England, Wales, and Northern Ireland. It’s published by the AHDB (Agriculture and Horticulture Development Board)
Go to AHDB Website and download resources
RB209 Video Playlist
RB209 Nutrient Management Guide
Section 1: Principles of Nutrient Management and Fertiliser Use
🎯 Key Principles
Good nutrient management balances economic efficiency with environmental protection through:
Test pH, P, K, and Mg every 3-5 years to maintain optimal soil conditions. Regular testing helps identify nutrient deficiencies early and prevents over-application of fertilisers.
Assess soil nitrogen supply before each fertiliser application. This ensures you apply the right amount at the right time, maximizing crop uptake and minimizing losses.
Maximize use of organic materials to reduce fertiliser requirements. Organic materials improve soil structure, increase organic matter, and provide a slow-release source of nutrients.
Apply fertilisers at the right time, in the right amounts, with calibrated equipment. Proper calibration and timing prevents waste, reduces environmental impact, and ensures even crop growth.
Maintain detailed field records for informed decision-making. Good records help track nutrient balances, identify trends, and ensure regulatory compliance.
🌿 Major Nutrients Covered
Nitrogen (N)
Most dynamic nutrient requiring annual assessment through Soil Nitrogen Supply (SNS) Index system. Recommendations based on crop requirement minus soil supply.
Key points:
- Annual assessment essential
- SNS Index system (0-6)
- Timing critical for uptake efficiency
- Risk of leaching and gaseous losses
Phosphorus (P) & Potassium (K)
Managed by maintaining target Soil Indices (Index 2 for most crops). Apply maintenance dressings to replace crop offtake, or build-up applications if below target.
Key points:
- Target Index 2 for arable and grassland
- Maintenance = replacement of offtake
- Build-up over 5-15 years if low
- Soil test every 3-5 years
Magnesium (Mg)
Monitor through soil testing; apply when at Index 0-1, especially for sensitive crops like potatoes, sugar beet, and vegetables.
Key points:
- Apply 50-100 kg/ha MgO at Index 0-1
- Sensitive crops most at risk
- Magnesian limestone provides long-term supply
- Common deficiency on sandy/light soils
Sulphur (S)
Increasingly important due to reduced atmospheric deposition. Apply to high-risk situations based on soil type and rainfall patterns.
Key points:
- Atmospheric deposition greatly reduced
- OSR and grass silage particularly sensitive
- High risk on sandy/chalky soils
- Annual application needed
🌍 Environmental Challenges Addressed
- Reducing greenhouse gas emissions (especially nitrous oxide – 300x more potent than CO2)
- Protecting water quality from nutrient pollution
- Minimizing ammonia emissions to air (agriculture accounts for ~90% of UK emissions)
- Maintaining soil health and organic matter levels
🪴 Soil Management
pH Optimization
- pH optimization is critical: typically 6.0-6.5 for grass, 6.5 for arable crops
- Lime recommendations based on soil texture and current pH
- Regular monitoring: soil pH should not vary by more than ±0.5 units from optimum
- Good soil structure essential for nutrient efficiency and root development
🔧 Practical Tools
🗺️Field Assessment Method
Use field-specific information for SNS determination without soil sampling.
🔬Measurement Method
Laboratory-based soil analysis for precise nitrogen supply assessment.
📏Soil Index System
0-9 scale for P, K, and Mg to guide fertiliser applications.
⚙️Adjustment Factors
Modify recommendations based on soil types and expected yields.
🧮Break-Even Ratio
Calculate economic optimum nitrogen rates based on crop value and fertiliser cost.
🌍Practices making best economic use of nutrients also protect the environment