Foliar Fertilizing Specialty Crops
Supplemental and Corrective Foliar Fertilizing of Specialty Crops
Foliar fertilization offers growers the ability to supplement their regular feeding regime or to quickly overcome unforeseen nutrient deficiency.
Several factors to consider when mixing foliar fertilizer solutions are:
- Proper Spray Equipment — construction material and spray droplet size
- Solubility — the fertilizer must be soluble in water to be effective as a foliar fertilizer
- Concentration — the ideal concentration range should be selected according to the kind of nutrient (macro- or micronutrient), plant species, plant age, nutritional status, and weather conditions
- Point of Deliquescence (POD) — low POD helps prolong the time the fertilizer is in solution while in contact with the plant surface
- Leaf wetting — the ability of the solution to spread evenly across the waxy cuticle surface of plant leaves
- Solution pH — avoid extremes in pH; adjust foliar fertilizer solutions to a range of 5–6.5
- Electric Charge — plant cuticles are negatively charged; uncharged or negatively-charged compounds and anions penetrate the leaf and translocate in the apoplast more easily than positively-charged cations
- Environmental factors — relative humidity and temperature affect foliar spray performance and uptake; environment also alters efficacy through its influence on plant biology
Formulations and Adjuvants
Foliar nutrient sprays are generally composed of two major components: the active ingredient and inert materials or adjuvants. Adjuvants improve the spreading (wetting) and persistence (sticking) of mineral elements on the leaf surface, and increase the rate of uptake and bioactivity. Browse adjuvants that improve the performance of spray treatments.
Mineral Compounds Applied as Foliar Sprays
A preliminary distinction should be made between macro- and micro-nutrients — the latter supplied at lower rates and concentrations, and often unstable when applied as inorganic salts. The tables below list the pure mineral and high-performance chelated fertilizer compounds Custom Hydro stocks for foliar use.
| Macronutrient | Foliar Fertilizer Compound |
|---|---|
| Nitrogen | Urea (low biuret), Ammonium Sulfate, Calcium Nitrate, Magnesium Nitrate, Protein Hydrolysate (Ferti-Nitro Plus, 3D Soluble Fish) |
| Phosphorus | Phosphoric Acid, Mono Potassium Phosphate, Mono Ammonium Phosphate, Phosphite |
| Potassium | Potassium Acetate, Potassium Amino Acid Complex, Potassium Carbonate, MKP, Potassium Nitrate, Potassium Sulfate, Potassium Silicate |
| Calcium | Calcium Amino Acid Chelate, Calcium Chloride, Calcium Nitrate |
| Magnesium | Magnesium Amino Acid Chelate, Magnesium Nitrate, Magnesium Sulfate |
| Sulfur | Magnesium Sulfate |