The Neglected Plant Nutrient

The neglected plant nutrient, carbon, is arguably the most important plant nutrient because, out of seventeen recognized plant nutrients, carbon makes up the largest portion of the plant’s dry weight.  Is it realistic to expect all this carbon to come from atmospheric CO2?  Are you including  carbon with your N, P, and K?


Humic Acids and Lignins: Prebiotics for Soil
Relationship Between Plant Lipid Bodies and Fungal Endophytes

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Carbon (C)
(Widely recognized by plant biologists, carbon is the neglected nutrient in practice.  Carbon makes up about 50 percent of the plant’s dry weight.  It is important for structure, function, and energy.

Nitrogen (N) – Essential for DNA, protein, ATP, and many defense molecules (ex. polyamines).  Nitrogen is the most commonly used fertilizer ingredient, and is often applied in excess.

Oxygen (O) – Essential for DNA, sugars, proteins, fatty acids, and more.  Oxygen can be obtained from water, from soil, or from the atmosphere.

Phosphorus (P) – Essential for DNA, phospholipids, energy molecules, and more.  Phosphorus is usually obtained from the soil, and is commonly added as fertilizer.

Potassium (K) – This element is essential for helping the plant maintain osmotic balance and aids in metabolism of other nutrients.   It also helps plants manage stress.

Sulfur (S)-Sulfur is an essential component of two different amino acids that are used to make proteins.  It aids in chlorophyll formation and plays a role in managing metabolic wastes or  toxins.

Calcium (Ca) – Calcium is important for development of cell walls and for intracellular signalling.

Magnesium (Mg)-Magnesium is essential for chlorophyll development and aids in utilization of cellular energy (stored as ATP).

Iron (Fe) – Iron plays a key role in electron transport.  All plant metabolic pathways require energy, which is usually obtained through electron transport processes.

Boron (B) – Boron is essential for cell wall formation, cell membrane structure, translocation of energy, pollination, and seed set.

Nickel (Ni) – Important for nitrogen metabolism

Chlorine (Cl) – supports photosynthesis, may help maintain osmotic balance.

Zinc (Zn) – Zinc is a component of many enzymes involved in DNA transcription.

Molybdenum (Mo) – Molybdenum is a component of enzymes involved in nitrogen, carbon, and sulfur metabolism

Cobalt (Co) – This element has only recently been proposed as an essential nutrient for plants. It’s roles in nitrogen fixation, not only in legumes, but in the symbiotic bacterial that colonize leaves, stems, and roots of all plants, make it invaluable for maintaining plant nitrogen levels.   Cobalt is also important for production of vitamin B12.


0:00  In human nutrition, nutrients include small molecules.  In plants, recognized essential nutrients are elements.
0:50 Plants and microbes work together to convert elements to nutrition.

1:19 Plant essential nutrients are classified as macronutrients and micronutrients

2:53  Less than 3% of a plant’s biomass is made up of the three most widely applied nutrients: Nitrogen (N), Phosphorus (P), and Potassium (K).

5:15  The neglected nutrient, carbon, makes up 45-50% of a plant’s dry weight.

7:18   Mycoheterotrophy is a symbiotic relationship between plants and fungi through which a plant obtains some or all of its carbon from fungi rather than from photosynthesis.

9:17  Three facts to remember about carbon as a plant nutrient.

10:15 How to add carbon to your soil.

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