Peer-reviewed publications report beneficial effects on plant growth, soil fertility, crop productivity and livestock nutrition. Agricultural meta-analyses and controlled trials provide the strongest evidence. Animal studies also report benefits, although findings are less consistent. Explore 9 selected publications below.
Average changes against controls in Ma, Cheng and Zhang (2024): 120 publications and 479 observation pairs overall. Different data subsets contribute to each outcome.
Study detailsAverage changes reported by Rose and colleagues (2014). These values concern biomass, not crop yield increases.
Study detailsThese are aggregated research findings, not guaranteed outcomes for every humic-acid product. Source material, concentration, application rate, crop, soil and environmental conditions influence the results.
Meta-analyses, physiological mechanisms and fulvic-acid trials under drought: four publications on plant growth, nutrition and productivity.
The Impact of Humic Acid Fertilizers on Crop Yield and Nitrogen Use Efficiency: A Meta-Analysis
Ma, Y.; Cheng, X.; Zhang, Y. · Agronomy · 2024
What was studied: 120 publications and 479 paired observations overall examining humic-acid fertilizers in field agriculture.
Positive findings: Average improvements of 12% in crop yield, 27% in nitrogen use efficiency and 17% in nitrogen uptake.
Conclusion: The meta-analysis supports the potential of humic amendments to improve productivity and nitrogen management. Effects depend on environmental conditions; different data subsets contribute to each outcome.
Read the publication DOI: 10.3390/agronomy14122763
A Meta-Analysis and Review of Plant-Growth Response to Humic Substances: Practical Implications for Agriculture
Rose, M. T.; Patti, A. F.; Little, K. R.; Brown, A. L.; Jackson, W. R.; Cavagnaro, T. R. · Advances in Agronomy · 2014
What was studied: Relationships between humic substances, plant biomass, application rate and the origin of the organic material.
Positive findings: Average increases of 22% in shoot dry biomass and 21% in root dry biomass.
Conclusion: Humic substances can stimulate growth, but effectiveness varies substantially. Compost-derived materials performed particularly well in the analyzed trials. The percentages concern biomass, not crop yield.
Read the publication DOI: 10.1016/B978-0-12-800138-7.00002-4
Physiological responses to humic substances as plant growth promoter
Canellas, L. P.; Olivares, F. L. · Chemical and Biological Technologies in Agriculture · 2014
What was studied: Physiological mechanisms explaining how humic substances influence root development and nutrient absorption.
Positive findings: Increased root branching, root hair development and stimulation of H⁺-ATPase, an enzyme associated with nutrient transport.
Conclusion: Humic substances can influence plant physiology directly, as well as acting as a soil amendment.
Read the publication DOI: 10.1186/2196-5641-1-3
The Impact of Fulvic Acid on the Growth Physiology, Yield, and Quality of Tomatoes Under Drought Conditions
Song, H.; Zhu, W.; Guo, Z.; Song, T.; Wang, J.; Gao, C.; Zhang, H.; Shen, R. · Agronomy · 2025
What was studied: Fulvic-acid application to tomatoes subjected to drought during seedling and fruiting stages.
Positive findings: Beneficial effects on physiological performance, yield and fruit quality in water-stressed plants.
Conclusion: Fulvic acid shows potential to mitigate some adverse effects of drought on tomato production. Responses are specific to the tested conditions.
Read the publication DOI: 10.3390/agronomy15071528
Five publications on dairy cows, pigs and poultry examine productivity, digestion and immune indicators. Benefits depend on the preparation and dose; some outcomes remain unchanged or worsen.
Prepartum Dietary Supplementation of Potassium Humate Improves Postpartum Lactation Performance, Metabolic Profile of Multiparous Cows, and Immune Response of Their Calves
Uyarlar, C.; Rahman, A.; Gultepe, E. E.; Cetingul, İ. S.; Akhtar, M. U.; Bayram, I. · Animals · 2025
What was studied: 75 dairy cows receiving different dietary concentrations of potassium humate during the dry period before calving.
Positive findings: The 0.5% treatment improved subsequent milk production and certain metabolic indicators. Some treatments increased colostrum and calf IgG concentrations.
Conclusion: Potassium humate may benefit lactation performance, but the response was dose-dependent. The 2% treatment adversely affected some measured outcomes.
Read the publication DOI: 10.3390/ani15020279
Effects of Dietary Supplementation of Humic Acid Sodium and Zinc Oxide on Growth Performance, Immune Status and Antioxidant Capacity of Weaned Piglets
Wang, Q.; Ying, J.; Zou, P.; Zhou, Y.; Wang, B.; Yu, D.; Li, W.; Zhan, X. · Animals · 2020
What was studied: 72 weaned piglets over 30 days, receiving sodium-humate feed, a zinc-oxide and antibiotic comparison treatment, or control feed.
Positive findings: Improved average daily gain, feed-to-gain ratio and immunoglobulin levels, with lower diarrhea incidence and some inflammatory markers.
Conclusion: Sodium humate showed potential in this controlled trial. The findings do not establish that all humic products can replace approved veterinary treatments.
Rounded averages for the 30-day trial by Wang and colleagues (2020), comparing the tested sodium humate with control feed.
Read the publication DOI: 10.3390/ani10112104
Humic acid as a feed additive in poultry diets: a review
Arif, M.; Alagawany, M.; Abd El-Hack, M. E.; Saeed, M.; Arain, M. A.; Elnesr, S. S. · Iranian Journal of Veterinary Research · 2019
What was studied: Published evidence on humic acids in the nutrition of broilers and laying hens.
Positive findings: Some experiments report better growth, nutrient digestibility, intestinal characteristics and feed conversion.
Conclusion: Humic acids have potential as poultry feed additives, but findings are inconsistent across experiments and doses.
Read the publication PMID: 31656520 · PMCID: PMC6811714
Effects of Humic Acid and Blueberry Leaf Powder Supplementation in Feeds on the Productivity, Blood and Meat Quality of Finishing Pigs
Kim, K.; Bae, I.; Cho, J.; Choi, Y.; Ha, J.; Choi, J. · Food Science of Animal Resources · 2019
What was studied: Humic acid alone and combined with blueberry leaf powder in finishing pig diets.
Positive findings: Favorable changes in certain lipid-profile and meat-quality measures.
Conclusion: Potential improvements in selected physiological and meat-quality parameters, without a demonstrated improvement in feed efficiency from humic acid alone.
Read the publication DOI: 10.5851/kosfa.2019.e22
Dietary Supplementation of Inorganic, Organic, and Fatty Acids in Pig: A Review
Ferronato, G.; Prandini, A. · Animals · 2020
What was studied: A review of several acid classes in pig nutrition, including a dedicated section on fulvic acids.
Positive findings: The review describes studies reporting better mineral utilization, feed efficiency and serum IgG, alongside reduced backfat thickness.
Conclusion: It provides useful evidence specifically concerning fulvic acids, although the underlying trials require individual assessment.
Read the publication DOI: 10.3390/ani10101740
A brief overview by application. Assessments reflect the selected publications and are not a formal grading of evidence quality.
| Application | Humic acids | Fulvic acids | Overall assessment |
|---|---|---|---|
| Root development | Strong supporting research | Supporting research | Well-supported potential |
| Crop yield | Field-trial meta-analysis | Crop-specific trials | Positive, conditions-dependent |
| Nutrient uptake | Strong supporting research | Supporting research | Promising |
| Drought resistance | Experimental evidence | Tomato experiments | Promising |
| Soil management | Established soil interactions | Mineral interactions | Dependent on soil and product |
| Dairy production | Controlled animal studies | Limited direct evidence | Preliminary |
| Pig growth and nutrition | Controlled animal studies | Positive studies reviewed | Promising but inconsistent |
| Poultry productivity | Mixed findings | Limited direct evidence | Inconclusive |
Independent research groups and meta-analyses support the positive biological and agricultural potential of humic substances. Evidence is clearest for plant growth and nutrient utilization. Fulvic-acid and livestock applications show encouraging results but need more targeted confirmation. For ProtoHumiX, these publications provide a scientific rationale for testing; the performance of its particular formulation requires product-specific trials.
This table compares a high-tech biostimulant (manufactured in the EU using patented technology) with a product of unknown origin and quality, based on key criteria from Regulation (EU) 2019/1009 and good control practices.
| Requirement | High-tech biostimulant (EU / patented technology) | Biostimulant of unknown origin and quality |
|---|---|---|
| CE certificate (EU 2019/1009) | CE certified in the EU and has a CE certificate number issued by an official EU notified certification body, supported by patented (official) production technology, compliant quality parameters under Regulation (EU) 2019/1009, and long-term successful field trials. | Does not have a European CE certificate under Regulation (EU) 2019/1009. It may present other unclear “certificates” issued by non-official or questionable bodies, or by non-accredited laboratories. |
| Public/official technology (patent/publication) |
Has:
|
Does not have:
|
| Official analyses under Regulation (EU) 2019/1009 |
Has an official analysis report issued by a certified laboratory accredited to perform tests
according to
Regulation (EU) 2019/1009.
The report includes full information about chemical composition, quality indicators, and the content of hazardous elements defined in Regulation (EU) 2019/1009. |
Analysis reports do not provide complete data about the product’s chemical composition.
Testing is performed by laboratories without the required accreditation under Regulation (EU) 2019/1009. |
| Safety: toxic/harmful elements, impurities & microorganisms |
Does not exceed the maximum permissible limits:
|
May exceed permissible limits for toxins, heavy metals, and harmful substances due to inadequate production and purification processes. |
| Biologically active acids (humic type) |
High-tech non-microbial biostimulants should contain a high concentration of humic-type
acids, such as:
|
Low levels of humic and fulvic acids.
Low percentage of free active water-soluble humic and fulvic acids. |
| Expected outcome in practice |
|
Depleted soil
Increased use of mineral fertilizers Lower-quality production with potential residues of harmful chemicals and microorganisms |