Cobalt (Co)
Role in plants
Cobalt is not essential for most plants but is beneficial for legumes, where it supports nitrogen fixation through its role in rhizobia metabolism.
Deficiency symptoms
- Poor nodulation in legumes
- Reduced nitrogen fixation
- Weak growth in cobalt-responsive systems
Toxicity symptoms
- Chlorosis
- Reduced root growth
- Narrow safety margin at higher concentrations
Natural sources
- Soil minerals
- Organic matter
Fertiliser sources
- Cobalt sulphate (rare, specialist use)
- Trace impurity in some fertilisers
Plant interaction form