Nutrients

This chapter is based on Joel Williams's talk on Advanced Plant Nutrition that touches on all key primary, secondary, and micronutrients that are essential for healthy plant development.

Chelation

Chelators are carbon sources that help the absorption of nutrients by attaching to the nutrient element and neutralizing its negative charge, making them more available and easier to uptake by plants. This can be molasses, seaweed, fish extract, humic acids, or fulvic acids. Fulvic acids are especially good for foliar feeding as it makes the leaves more permeable, making them more receptive of the nutrients applied along with fulvic acid.

Mobility

Once the plants have taken up the nutrients they need to utilize them by sending them to a part of the plant where they are required. Some elements are immobile and once they are absorbed they cannot be sent to other parts of the plant. Other elements are mobile and can be reallocated to new growth from old parts of the plant.

• Mobile elements (Deficiencies on old leaves) : Nitrogen [N], Phosphorus [P], Potassium [K], Magnesium [Mg], Chlorine [Cl], Zinc [Zn], Molybdenum [Mo], and Nickel [Ni]

• Immobile elements (Deficiencies on new leaves): Calcium [Ca], Sulfur [S], Boron [B], Copper [Cu], Iron [Fe], and Manganese [Mn]

Leaf sink-source dynamic

• Young leaves (Sink): Exclusively import nutrients from older leaves until they are mature and become a source for newly developing leaves.

• Old Leaves (Source): Exclusively export nutrients to younger leaves and once mature cannot receive nutrients from younger leaves.

Primary nutrients

Nitrogen [N]

Mobile. Crucial for structural components like DNA, chlorophyll, and proteins. A big driver of yield, needed for photosynthesis, production of amino acids, and proteins for DNA.

Synergists: Molybdenum [Mo], Nickel [Ni], Sulfur [S]

Available as: Ammonium sulfate, Calcium nitrate, Amino acids, Fish hydrolysate, Urea (Foliar)

Phosphorus [P]

Somewhat mobile. Part of the ATP molecule, stores energy in cells, driving all processes in plants. Important in root development, accelerates tissue maturity (pathogen, pest, and disease protection).

Antagonists: Aluminium [Al], Calcium [Ca], Iron [Fe], Zinc [Zn]

Synergists: Magnesium [Mg]

Available as: Phosphorus acids (pH down solution), Monopotassium phosphate, Micronised rock phosphates

Potassium [K]

Highly mobile. Catalyzes all sorts of reactions in the plant, part of many enzyme systems, important in Nitrogen utilization. Involved in the movement of sugars and carbohydrates to the fruit and seeds, important in fruit size, improves flavor and quality.

Antagonists: Calcium [Ca], Magnesium [Mg], Nitrogen [N], Phosphorus [P], Sodium [Na]

Synergists: Manganese [Mn], Silicon [Si]

Available as: Potassium sulfate, Potassium chloride, Potassium nitrate, Potassium silicate

Secondary nutrients

Calcium [Ca]

Highly immobile. Deposited in cell walls, makes the plant more resilient against pest and disease by creating a barrier between the outside world and the plant itself. Helps to build strong, structural, rigid plant tissue that is resistant to mold, fungus, insects, and diseases.

Antagonists: Nitrogen [N], Phosphorus [P], Potassium [K], Magnesium [Mg]

Synergists: Boron [B], Silicon [Si]

Available as: Calcium nitrate, Calcium chloride, Liquid lime/gypsum

Magnesium [Mg]

Somewhat mobile. A structural building block of chlorophyll. Catalyzes protein synthesis and Nitrogen utilization. Needed for photosynthesis to produce sugars, carbohydrates, hormones, fats, oils, and protective compounds.

Antagonists: Calcium [Ca], Potassium [K]

Synergists: Phosphorus [P], Nitrogen [N]

Available as: Magnesium sulfate (Epsom salt), Magnesium nitrate, Micronised magnesite

Sulfur [S]

Mobile. An important part of nitrogen utilization, helps to build amino acids and forming proteins, enzymes, and vitamins. Important for root development, nodule formation, and disease resistance.

Antagonists: Zinc [Zn], Molybdenum [Mo]

Synergists: Selenium [Se]

Available as: Ammonium sulfate, Potassium sulfate, Magnesium sulfate (Epsom salt), trace mineral sulfates

Micronutrients (Tertiary/Trace)

Silicon [Si]

Highly immobile. Deposited in cell walls, makes the plant more resilient against pest and disease by creating a barrier between the outside world and the plant itself. Increases Calcium uptake, boosts the plant's immune system, improves frost, heat, drought, salinity, sodium, and heavy metal resistance.

Boron [B]

Highly immobile. Deposited in cell walls, makes the plant more resilient against pest and disease by creating a barrier between the outside world and the plant itself. Responsible for sugar movement around the plant and synthesis of structural compounds (lignin, polyphenols). Required in growing tips and all parts of the reproductive processes (flowers, fruit-sets, seed-sets, pollen).

Foliar: Recommended to apply 1 week before moving into flowering till going into flowering.

Antagonists: Calcium [Ca] (if ratio is incorrect), Nitrogen [N], Potassium [K]

Available as: Sodium borate, Boric acid

Copper [Cu]

Immobile. Part of defense chemicals for disease resistance: Responsible for the synthesis of lignin for primary defense, and antimicrobial compounds for secondary defense. Toughens up the skin of the plant and helps respiration. Also, part of protein and carbohydrate metabolism.

Foliar: Used to sterilize the leaf surface, protect against disease.

Antagonists: Nitrogen [N], Phosphorus [P]

Synergists: Molybdenum [Mo]

Available as: Copper sulfate

Zinc [Zn]

Immobile. Plays a role in determining leaf size - area available to capture sunlight. , auxin production. Involved in the synthesis of chlorophyll,

Foliar: Added as Zinc oxide.

Antagonists: Phosphorus [P], Calcium [Ca], Magnesium [Mg]

Available as: Zinc sulfate, Zinc oxide (Foliar)

Manganese [Mn]

Mobile. Reproductive processes: Germination and seed development. The key disease-fighting nutrient in both primary and secondary plant defenses (Phytoalexin). Important in lignification (Tissue becoming wood-like), callus formation (soft tissue covering cuts/damage).

Antagonists: Calcium [Ca], Copper [Cu]

Synergists: Potassium [K]

Available as: Manganese sulfate

Iron [Fe]

Immobile. Involved in the synthesis of chlorophyll, brings the Nitrogen and Magnesium elements together to form the chlorophyll pigment.

Antagonists: Calcium [Ca], Copper [Cu], Manganese [Mn], Phosphorus [P], Zinc [Zn]

Synergists: Potassium [K]

Available as: Iron sulfate, Iron chelate

Molybdenum [Mo]

Mobile. Needed in protein synthesis and for Nitrogen utilization (converting nitrate into ammonia, before it is converted into amino acids). Helps in the absorption of Nitrogen gas from the air for the supporting bacteria/microbes.

Available as: Sodium molybdate

Cobalt [Co]

Immobile. Used in Nitrogen fixation, where Nitrogen and air are converted into ammonia. Part of vitamin B12 (involved in cell division).

Available as: Cobalt sulfate

Nickel [Ni]

Mobile. Important in urea (carbamide) utilization, turning it into amino acids and proteins. Has a role in nitrogen metabolism.

Foliar: Sprayed along with urea that builds into the plant as a "pre-amino acid" that is energy efficiently converted into proteins.