H
Hydrogen (H)
Fundamental component of water (H₂O) and all organic compounds. Drives proton gradients essential for energy transfer and nutrient transport. Note: Supplied via water; not affected by fertiliser inputs.
pH relevance: Not pH-dependent (water availability is the key factor).
Li
Lithium (Li)
Not an essential plant nutrient. Only observed effects occur at ultra-trace levels in experimental conditions. Practical: No agronomic role.
pH relevance: No known plant uptake dependency in standard soils.
B
Boron (B)
Essential for cell wall formation, membrane integrity, and reproductive development (flowering, fruit set). Deficiency: death of growing points, poor fruit/seed set.
pH lockout: becomes unavailable in high pH soils (>7.5) and leaches easily in sandy acidic soils.
C
Carbon (C)
Structural backbone of all plant organic compounds. Acquired via CO₂ through photosynthesis. Limiting factor: light and leaf area, not soil nutrition.
pH relevance: not soil-controlled..
N
Nitrogen (N)
Primary driver of vegetative growth and chlorophyll production. Deficiency: uniform yellowing of older leaves. Highly mobile in soil and plant.
pH lockout: best availability around pH 6–8; losses increase in very acidic soils due to leaching and volatilisation.
O
Oxygen (O)
Essential for root respiration and energy production. Controls nutrient uptake efficiency in roots.
pH relevance: not pH-dependent, but strongly affected by soil compaction and waterlogging.
Na
Sodium (Na)
Not essential for most plants but can partially substitute potassium in some C4 and CAM species. Risk: excess leads to salinity stress and soil structure decline.
pH relevance: more influenced by salinity and sodicity than pH directly.
Mg
Magnesium (Mg)
Central atom in chlorophyll and essential for enzyme activation and energy metabolism. Deficiency: interveinal chlorosis on older leaves.
pH lockout: reduced availability in acidic soils (<6) and highly alkaline soils (>8.5).
Al
Aluminium (Al)
Not a required nutrient. Becomes toxic in acidic soils, restricting root growth and nutrient uptake.
pH lockout effect: becomes more soluble and toxic below pH 5.5.
Si
Silicon (Si)
Beneficial element that strengthens cell walls, improves drought tolerance, and reduces pest/disease pressure. Important in high-stress crops.
pH relevance: more available in neutral to slightly alkaline soils; uptake decreases in strongly acidic conditions.
P
Phosphorus (P)
Critical for energy transfer (ATP), root development, flowering, and seed formation. Deficiency: poor early root growth and delayed maturity.
pH lockout: strongly fixed in acidic soils (<6) by iron/aluminium and in alkaline soils (>7.5) by calcium.
S
Sulfur (S)
Required for amino acids and enzyme systems. Important for chlorophyll formation. Deficiency: yellowing of younger leaves.
pH relevance: generally available across most pH ranges but can leach in sandy soils.
Cl
Chloride (Cl)
Micronutrient involved in osmosis and photosynthesis (oxygen evolution). Deficiency: rare in most soils.
pH relevance: not strongly pH-limited; more influenced by soil moisture and salinity.
K
Potassium (K)
Regulates water balance, enzyme activation, and stress tolerance. Improves fruit quality and drought resistance. Deficiency: leaf scorch and weak stems.
pH lockout: reduced availability in very acidic soils and high-magnesium or high-calcium antagonism systems.
Ca
Calcium (Ca)
Structural nutrient essential for cell wall integrity and root development. Immobile in plants, requiring continuous supply. Deficiency: distorted new growth and physiological disorders.
pH lockout: low availability in acidic soils (<6); excessive Ca in alkaline soils can suppress Mg and K uptake.
Mn
Manganese (Mn)
Important in photosynthesis and enzyme activation. Deficiency: interveinal chlorosis, often mistaken for iron deficiency.
pH lockout: strongly unavailable in alkaline soils (>7.5); toxicity can occur in acidic soils (<5.5).
Fe
Iron (Fe)
Essential for chlorophyll formation and electron transport in photosynthesis. Deficiency: yellowing of young leaves with green veins.
pH lockout: becomes insoluble in alkaline soils (>7); most common deficiency in high pH conditions.
Co
Cobalt (Co)
Supports nitrogen-fixing bacteria in legumes rather than direct plant metabolism.
pH relevance: availability reduced in highly alkaline soils.
Ni
Nickel (Ni)
Required for urease enzyme activity and nitrogen metabolism. Deficiency: rare but affects nitrogen utilisation.
pH lockout: low availability in very alkaline soils.
Cu
Copper (Cu)
Important for photosynthesis, lignin formation, and reproductive growth. Deficiency: dieback and poor flowering.
pH lockout: reduced availability in alkaline soils (>7.5); toxicity more likely in acidic soils.
Zn
Zinc (Zn)
Essential for hormone regulation and enzyme activity. Deficiency: stunted growth and distorted young leaves.
pH lockout: strongly unavailable in alkaline soils (>7); common deficiency in high pH turf systems.
Se
Selenium (Se)
Beneficial element in trace amounts for some plants and microbial systems. Caution: toxicity occurs at low thresholds depending on soil type.
pH relevance: more available in alkaline soils, increasing toxicity risk.
Sr
Strontium (Sr)
No confirmed essential role in plant nutrition. Limited research on physiological substitution effects.
pH relevance: not well-defined in agronomic systems.
Mo
Molybdenum (Mo)
Essential for nitrate reduction and nitrogen fixation enzymes. Deficiency: resembles nitrogen deficiency due to impaired nitrate use.
pH lockout: uniquely becomes unavailable in acidic soils (<6), opposite of most micronutrients.
