From Foliar Feeding to Soil Health: A Practical Guide to Amino Acid Fertilizers

Industry perspective | August 2026
A practical guide to foliar feeding, fertigation, transplanting, stress management, crop recovery, and soil application.

Amino acid fertilizers are used in many crop programs, but they should not all be applied in the same way. A foliar spray for quick recovery has a different job from a root treatment used after transplanting. Products for drip irrigation also need different properties from ingredients added to a soil fertilizer.

This is especially relevant in 2026. Fertilizer prices remain under pressure, while heat, drought, salinity, and unstable weather can reduce nutrient uptake. Growers are therefore paying more attention to how and when an input is used, not only how much nutrient it contains. The best starting point is the application: foliar feeding, fertigation, root-zone treatment, stress management, or soil improvement. Product specifications can then be matched to that job.

Foliar application delivers a diluted solution directly to the leaves. It is often considered when crops need support during active growth, flowering, fruit setting, or early signs of nutrient stress. Free amino acid products are commonly used in foliar formulas because they are already in a small form. For example, PEPAID HA80 contains at least 75% total free amino acids and at least 13.5% total nitrogen, with a chloride limit of 3%.

A concentrated powder such as HA80 may be used as an ingredient in foliar fertilizers or combined NPK and micronutrient formulas. The final concentration should be selected according to the crop, growth stage, weather, and other ingredients in the tank.

Foliar spraying is generally better under mild conditions. Avoid strong heat, wind, or rain immediately after application. Run a small compatibility test before mixing with pesticides, calcium products, or concentrated fertilizers.

Fertigation applies nutrients through irrigation water. Products used in this system need good solubility and low insoluble material to reduce the risk of sediment or blocked emitters.
Liquid amino acid products are convenient because they are easier to meter into an irrigation system. PEPAID HA20L is positioned for fertigation, hydroponics, and quick foliar use. Its published specification lists at least 18% total amino acids and full solubility in a 5% water solution.

For chloride-sensitive crops or soils where salt is already a concern, chloride level needs closer attention. HA20-LLC contains at least 22% total amino acids and no more than 1.5% chloride. This makes it a more suitable starting point for low-chloride liquid formulas and drip-irrigation programs. Before fertigation, check water pH, hardness, and compatibility with the stock solution. Flush the irrigation line after application, especially when several fertilizers are used in the same system.

Transplanting can temporarily slow root activity. Seedlings may need time to establish new lateral roots and root hairs before normal water and nutrient uptake resumes. Lower-molecular-weight peptides are one option for products designed around root establishment. The PEPAID EA Series includes EA80-LMW with an average molecular weight of 700-900 Da. It is positioned for early-stage root support, transplant recovery, and preparation before expected stress.

Plant-derived products may also be considered. PEPAID EP60P is a soybean enzymatic hydrolysate intended for root establishment and flowering-stage programs. A root-support product may be applied through a transplant drench, drip line, or early foliar program. Apply when the root zone has enough moisture. Amino acid inputs cannot correct poor drainage, damaged roots, or unsuitable planting depth.

Stress-management products are most useful when they are part of a planned program. If a heat wave, dry period, or saline irrigation cycle is expected, an application may be timed before the crop shows serious damage.

EA80-LMW is positioned for this pre-stress stage. For saline-alkali conditions, the plant-derived EP60 grade is another relevant option. Its specification lists at least 8.5% total nitrogen and at least 1.5% alpha-amino nitrogen.

The goal of a pre-stress application is supportive rather than corrective. It should be combined with practical measures such as correct irrigation timing, suitable soil moisture, good drainage, and careful control of fertilizer salt levels.

After heat, drought, salinity, cold, or chemical stress, plants may show slow growth, weak color, or reduced root activity. At this stage, heavy fertilizer application can sometimes add more salt pressure. Smaller peptide or free amino acid products may be considered in recovery formulas. PEPAID EA80-uLMW has an average molecular weight of 500-700 Da and is positioned for faster post-stress use. HA-series free amino acids can also be used where quick nutrient delivery is the main goal.

Recovery applications should begin only after the main cause of damage has been controlled. For example, irrigation must be corrected before treating drought stress, and a spray injury problem should be identified before another tank mix is applied. Start with a conservative rate and observe the crop response.

Not every amino acid product is intended for fast foliar use. Larger peptides, fermented materials, and products containing organic acids may be more relevant to soil or base-fertilizer programs.

PEPAID EA80 has a published average molecular weight of 6,000-7,000 Da and is positioned for longer root-zone and soil-conditioning use. It may be considered in base fertilizers, soil drenches, or programs for low-organic-matter and degraded soils.

PEPAID FP90 is a corn fermentation product containing at least 90% free amino acids, at least 14% total nitrogen, and no more than 0.1% water-insoluble material. It also contains fermentation-derived organic acids and is positioned for soil formulas focused on pH balance and nutrient availability. These inputs should complement soil testing and balanced NPK management. They should not be used to guess at a missing nutrient or replace lime, drainage improvement, or other necessary soil corrections.

Whichever product is selected, follow a few basic steps:
1. Define the crop problem and expected result.
2. Choose foliar, irrigation, or soil application based on that goal.
3. Check the product specification, chloride level, and solubility.
4. Test compatibility in a small container before tank mixing.
5. Begin with a small field trial and keep an untreated comparison where practical.
6. Record crop stage, weather, rate, and visible response.

The value of an amino acid fertilizer depends on fit. Matching the product form and specification to a real application is more useful than choosing a grade only because it has the highest amino acid percentage.

The following sources support the market figures, definitions, and agronomic context used in this article. Accessed August 2026.
• PEPAID Animal-Derived Free Amino Acids
• PEPAID Animal-Derived Enzymatic Polypeptides
• PEPAID Plant-Derived Protein Hydrolysates
• World Bank, Commodity Markets Outlook, April 2026
• FAO, Bioinputs and fertilizer-market volatility
• USDA NRCS, Nutrient Management

More information can be found in the links below