BIOMASS COMPOSITION, PROPERTIES, AND CHARACTERIZATION - Biomass as a Sustainable Energy Source for the Future - page 50

TABLE 2.6 Essential plant nutrients

Typical wt%
relative to N in
plant species'
dry tissue

Category of
nutrient Element Plant function

Nitrogen (N) 100 Amino acids, proteins

Potassium (K) 25 Enzyme activation, protein

synthesis, osmotic pressure
control, transport, cation/
anion balancing

Primary
macronutrients

Phosphorus (P) 6 Composing part of the

information carriers, nucleic
acids (deoxyribonucleic acid
(DNA), ribonucleic acid
(RNA)); energy household
carrier constituent, adenosine
diphosphate (ADP),
adenosine triphosphate (ATP)

Calcium (Ca) 12.5 Cell wall structural component

Magnesium (Mg) 8 Chlorophyll constituent Secondary

macronutrients

Sulfur (S) 3 Amino acids, proteins

Chlorine (Cl) 0.3 Photosynthesis reactions

Boron (B) 0.2 Cell wall component

Iron (Fe) 0.2 Chlorophyll synthesis

Manganese (Mn) 0.1 Activates enzymes Micronutrients

Zinc (Zn) 0.03 Activates enzymes

Copper (Cu) 0.01 Enzyme component

Molybdenum (Mo) 0.0001 Involved in N fixation

Adapted from Tortosa Masia (2010).

Some of the aforementioned elements that are important for mineral- and ash-
related problems in processing biomass are briefly discussed here.
Potassium is the macronutrient needed in plant life in the largest quantities after
nitrogen. For optimum plant growth, its demand is of the order of 1

5 wt% dry matter,
depending on the particular species, while the potassium concentration inmature plants
generally does not exceed 2 wt% dry matter. Potassium has a high mobility in plants at
all levels. Furthermore, it plays a key role in a large number of processes for plant
growth, which include activation of enzymes, protein synthesis, photosynthesis,
regulation of osmotic pressure, vascular transport, and cation/anion balancing.
The amount of calcium compounds incorporated in plants varies between 0.1 and
>5.0 wt% (db) depending on plant growth conditions, plant species, and plant part
(Marschner, 1993). This element might either be strongly bound to the plant structure
or is exchangeable at the cell walls. Like potassium, calcium is a nutrient that plays an

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