Legume Crops Fertilization Guide
Comprehensive nutrition program for soybeans, peas, and other legumes to boost nodulation, yield, and soil health.
Introduction to Legume Crops
Legume crops — including soybean, pea, lentil, chickpea, and various field-beans — play a unique role in agricultural systems thanks to their ability to form a symbiotic relationship with Rhizobium bacteria and fix atmospheric nitrogen.
While legumes reduce reliance on synthetic nitrogen fertilisers, they still demand balanced fertility of phosphorus (P), potassium (K), sulphur (S), magnesium (Mg) and certain trace elements to achieve optimal growth, nodulation and yield.
While legumes reduce reliance on synthetic nitrogen fertilisers, they still demand balanced fertility of phosphorus (P), potassium (K), sulphur (S), magnesium (Mg) and certain trace elements to achieve optimal growth, nodulation and yield.
Key Nutrient Requirements
| Nutrient | Function | Deficiency Symptoms | Fertilizer Focus |
|---|---|---|---|
| Nitrogen (N) | Supports vegetative growth, fixed naturally by nodules | Pale leaves, low biomass, poor nodulation | Inoculant + low starter N if soil is poor |
| Phosphorus (P) | Promotes root development and nodulation | Weak roots, limited nodules | Base fertilizer or seed-bed application |
| Potassium (K) | Improves pod setting and disease resistance | Weak stems, poor grain filling | Supplement during flowering stage |
| Sulfur (S) | Essential for amino acid formation and nodulation | Yellowing young leaves, low N fixation | Apply S-enriched fertilizers |
| Micronutrients (Mo, B, Zn) | Critical for nodule enzymes and seed formation | Poor nodulation, reduced yields | Foliar sprays or seed treatment |
Recommended Base Fertilization
Apply base fertility based on soil test. Example baseline program (adjust rates for soil test, climate and variety):
| Fertilizer Type | Recommended Rate (per ha) | Timing / Notes |
|---|---|---|
| NPK (e.g., 10-20-10 or 8-24-24) | 250–350 kg | Before planting — supports root & early growth |
| Lime / Dolomite | 1–2 t | Pre-plant if pH <6.0 — corrects acidity, supplies Ca & Mg |
| Organic matter (compost / manure) | 5–10 t | Soil preparation — improves structure & microbial activity |
| Rhizobium inoculant | Per seed weight / label | At sowing — essential for fields without recent legume history |
Topdressing & Growth-Stage Fertilization
Supplemental feeding improves consistency of yields, especially under suboptimal soils or high-yielding varieties.
| Growth Stage | Nutrient Focus | Recommended Material | Typical Rate / Notes |
|---|---|---|---|
| Pre-sowing / Sowing | P, K, S; inoculation | NPK 10-20-10; Rhizobium; Mo seed treatment | 250–350 kg base; inoculate seed as directed |
| Early vegetative (emergence to nodulation) | Root development; nodule initiation | Starter P/K; minimal starter N (10–20 kg N/ha) if soil N very low | Side-dress small N only when needed |
| Flowering | Micronutrients for nodulation & pod set | Foliar Mo (0.2–0.3%), B & Zn sprays | Apply at early bloom to maximize nodulation/pod set |
| Pod filling | K for seed fill and quality | Potassium sulfate / MOP | Split K application if soil K deficient |
| Post-harvest | Soil restoration | Incorporate residues; organic amendments | Builds soil N & OM for next crop |
Special Recommendations & Management
- Always perform a soil test before deciding final rates — adjust P, K and micronutrients accordingly.
- Use crop-specific Rhizobium inoculants for best nodulation (do not mix with incompatible seed treatments without testing).
- Avoid excessive pre-plant N — high N suppresses nodulation and biological fixation.
- On light or sandy soils, pay attention to Sulfur and K — deficiencies are common.
- Monitor crop mid-season and use foliar micronutrient sprays (Mo, B, Zn) when deficiency signs appear or when soil test indicates low levels.
Quick Reference – Recommended Rates (example)
| Item | Example Rate | Purpose |
|---|---|---|
| NPK 10-20-10 | 250–350 kg/ha | Base P & K for nodulation & early growth |
| Starter N (if required) | 10–20 kg N/ha | Support emergence in very low N soils |
| Foliar Mo | 0.2–0.3% solution | Enhance nodule enzyme activity at flowering |
| Lime (if pH <6.0) | 1–2 t/ha | Correct acidity, improve Ca & Mg availability |
Note: Rates are general guidance — always calibrate to local soil test results, crop variety and target yield.
Recommended Products
Terafon® GrainMax NPK 10-20-10
Ideal for early growth and root development.
Terafon® NPK 12-12-24 + B + Mo
Promotes flowering and pod filling, improves nitrogen fixation.
Terafon Micronutrient Blend
Balanced Mo, Zn, and B supplement for enhanced nodule activity.
Terafon® SoilVital
Organic-mineral soil conditioner to improve soil fertility and nutrient availability over time.
Application Guidelines by Growth Stage
Pre-sowing
Apply balanced NPK 10-20-10 and incorporate into soil.
Tillering
Apply NPK 12-12-24 + B + Mo during the reproductive stage to promote flowering, pod filling, and enhance nitrogen fixation.
Micronutrient Blend
Foliar MicroBoost to aid grain filling and pollination.
Grain Filling
Maintain K and B until grain maturation for higher weight.
Pro Tip: Combining balanced NPK base applications with targeted micronutrient foliar sprays can increase cereal yields by up to 15–20% depending on baseline soil fertility and variety.
Results & Benefits
- Higher yield and grain weight
- Improved nutrient use efficiency
- Stronger root and stem development
- Better drought and lodging resistance
- Uniform maturity and improved grain quality
Related Food Crops
Explore nutrition solutions for other food crops:
Contact & Resources
Need expert advice on fertilizing your cereal crops? Our agronomists will design a customized nutrient plan for your farm.
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