Improving nitrogen fixation in legume crops is one of the most valuable outcomes for farmers looking to reduce synthetic nitrogen use, increase soil fertility, and lift yields. A growing body of evidence from global trials supports the use of Effective Microorganisms (EM) to significantly enhance nodulation and biological nitrogen fixation in legumes such as peas, beans, and clover.
What Is Nodulation and Why It Matters
Nodulation is the formation of nodules on legume roots where beneficial bacteria—primarily Rhizobium species—convert atmospheric nitrogen into a plant-usable form. This process, known as biological nitrogen fixation (BNF), reduces the need for synthetic nitrogen fertilisers and supports long-term soil health.
How EM Supports Nodulation and Fixation
1. Boosting Rhizobial Populations and Root Colonisation
EM contains a mix of naturally occurring beneficial microbes including lactic acid bacteria, yeast, and photosynthetic bacteria. These organisms stimulate the native population of nitrogen-fixing rhizobia, helping them colonise roots more rapidly and form nodules sooner.
2. Improving Soil Structure and Microbial Environment
EM improves soil aggregation, porosity, and moisture retention—creating ideal conditions for root development and rhizobia activity. These soil changes directly support nodule initiation and growth.
3. Accelerating Nodulation Timing
Trials show that EM-treated legumes often develop nodules earlier than untreated plants—typically within 10–14 days post-emergence. Early nodulation allows the plant to benefit from nitrogen fixation during critical vegetative growth stages.
4. Stimulating Root Growth and Exudates
EM has been observed to stimulate root growth and increase the release of root exudates—chemical signals that attract rhizobia. This interaction increases the likelihood and density of nodulation sites.
5. Suppressing Root Pathogens
By reducing disease pressure in the rhizosphere, EM allows the plant to devote more energy to forming symbiotic relationships with Rhizobium rather than fending off stressors.
Results from Global Research
| Study | Location | Key Findings |
|---|---|---|
| Pakistan Research & Extension (CS-56) | Pakistan | +25–50% increase in nodule number and biomass across legumes |
| Nature Farming Conference Series | Asia | Faster nodule formation in soybean under EM treatment |
| Soil Microflora Study | Japan | Higher microbial diversity and activity in rhizosphere |
| Faba Bean Trial | Egypt | Increased N% in leaves and more nodules per plant |
What This Means for NZ Farmers
While much of this work has been conducted overseas, the results are highly applicable to New Zealand's cropping systems. We’ve seen comparable benefits in local legume trials where EM improved early growth, root health, and overall nitrogen availability. For pea growers, particularly in Canterbury, applying EM or any of our EMNZ Biostimulants at soil prep followed by Plant-Stim post-emergence offers a biological edge to maximise crop performance.
