Carbon (C)

Role in plants

Carbon is the backbone of all organic molecules in plants: sugars, starch, cellulose, proteins, lipids and nucleic acids. It is fixed during photosynthesis.

Deficiency symptoms

Not diagnosed as a classic nutrient deficiency. Growth limitation is usually due to low light, low CO₂ availability, poor leaf area, or stress reducing photosynthesis.

Toxicity symptoms

Not applicable in the fertiliser sense. Excess CO₂ can affect plant physiology in controlled environments but is managed as a climate parameter.

Natural sources

• Atmospheric CO₂
• Dissolved CO₂ / bicarbonate in water (minor for most crops)

“Fertiliser” sources (managed inputs)

• CO₂ enrichment in protected cropping

Plant uptake forms

• CO₂ (via stomata)