Peer-reviewed publication · Soil & plants · In the living system
A straw-derived fulvic acid raised greenhouse tomato yield at one soil rate, not at lower or higher rates.
This straw-derived fulvic acid raised greenhouse tomato yield at one soil rate only, and the material carries its own nitrogen and potassium, so a nutrient effect cannot be ruled out.
Zhang et al., 11 October 2021. Frontiers in Plant Science 12:736613. Manufacturer-funded study.
Scope, material and route
- Studied
- Tomato: cultivar Hezuo906 in pots; Huangmeiren and Zizhenzhu for germination; Zizhenzhu in hydroponics
- Design
- Three separate experiments, each a randomised complete block: greenhouse pot culture (Experiment 1), seed germination (Experiment 2) and hydroponic culture (Experiment 3)
- Setting
- Naturally lit greenhouse; pots of 5 kg of soil from an 18-year high-tunnel vegetable farm in Shanghai (pH 7.5, high available phosphorus)
- Material
- Corn straw steam-exploded, enzyme-hydrolysed and fermented to ethanol; the residual mash was dried. Reported as 69.5 percent fulvic acids, 30.3 percent total carbon, 5.63 percent total nitrogen, 3.09 percent K2O, pH 3.94
- Route
- Pots: base dressing mixed into soil before transplanting, or top dressing and foliar spray every 10 days, six times, from first fruiting. Germination and hydroponics: added to the solution
- Exposure
- Base dressing 0.3, 0.9, 2.7 or 8.1 g/kg soil; top dressing 0.3 g/kg; foliar 100 mg/L; solutions 0, 10, 20, 40, 80, 160, 320 and 640 mg/L. Study exposure, not application guidance.
- Duration
- 126 days from transplanting (pots); 7 days (germination); 21 days (hydroponics)
Study design
Experiment 1: greenhouse pots
126 days, cultivar Hezuo906. Mixed into soil before planting, or top dressing and foliar spray.
55 pots11 treatments, five pots each.
- 0.3 and 0.9 g/kg soilYield not different from control
- 2.7 g/kg soilAbout 35 percent more fruit, more fruit rather than larger fruit
- 8.1 g/kg soilYield not different from control
- Top dressing, foliar sprayYield not different from control
Experiment 2: seed germination
7 days, two cultivars, 0 to 640 mg/L.
3 replicatesPer concentration and cultivar, eight concentrations.
- GerminationHighest at 80 mg/L, not separated from control in either cultivar
- Vigour at 80 mg/LHigher in Huangmeiren only
Experiment 3: hydroponics
21 days, cultivar Zizhenzhu, 0 to 640 mg/L.
4 replicatesPer concentration, eight concentrations.
- Root length44.4 percent longer at 80 mg/L; also longer at 160
- Biomass40.8 percent more at 160 mg/L
- 320 and 640 mg/LNot different from control
- Leaf ironHigher concentration at 80 mg/L only
More study details
- Research question
- Do dose and application method change the effect of a straw-derived fulvic acid on tomato yield, quality, root growth and soil?
- Experimental unit and replication
- Pots: 11 treatments, five replicates. Germination: eight concentrations, three replicates per cultivar. Hydroponics: eight concentrations, four replicates
- Comparator
- Water in pots; 0 mg/L in germination and hydroponics. A second commercial fulvic acid (JY) was compared for top dressing and foliar spray
- Outcomes measured
- Yield, fruit number and size, plant dry matter, fruit juice minerals and metabolites, soil chemistry; germination rate, radicle length and vigour; root length, root tips, biomass, leaf C/N ratio and leaf mineral concentrations
Findings
Researchers tested a fulvic acid made from corn straw, a by-product of bioethanol fermentation, on tomato in three separate experiments. In greenhouse pots over 126 days, mixing it into the soil before planting at 2.7 g/kg was followed by about 35 percent more fruit by weight than the control, through more fruit rather than larger fruit. Rates of 0.3, 0.9 and 8.1 g/kg did not differ from the control, and neither did top dressing or foliar spray. In 21-day hydroponic culture, 80 to 160 mg/L lengthened roots and 160 mg/L raised plant weight, while higher concentrations did not. Fruit and leaf minerals were measured as concentrations, not total uptake. The producer co-funded the work, supplied the material and employed three of the authors.
| Outcome | Comparison or result | Interpretation |
|---|---|---|
| Fruit yield, pots, base dressing | 35.0 percent above control at 2.7 g/kg (P < 0.05); 0.3, 0.9 and 8.1 g/kg not different from control | A response at one middle rate only |
| Fruit number and fruit size, pots | Fruit number 44.4 percent above control at 2.7 g/kg (P < 0.05); fruit size did not differ in any treatment | More fruit, not larger fruit |
| Yield with top dressing or foliar spray | No treatment differed from control, for either fulvic acid | No supported yield effect from these methods |
| Plant and root dry matter, pots | No treatment differed from control; root dry matter at 2.7 g/kg was 1.71 against 1.83 g per plant | The yield rise came without more root mass in soil |
| Fruit juice minerals, pots | At 2.7 g/kg, calcium and zinc concentrations reported 31.4 and 43.1 percent higher but not separated from control; at 8.1 g/kg, potassium, magnesium, iron, zinc, manganese and copper higher (P < 0.05) | Concentrations, not total uptake; the largest mineral rise came at a rate that did not raise yield |
| Fruit sugars and aroma compounds | Soluble sugars and three aroma compounds unchanged in all treatments; some organic and amino acids reported higher as fold changes | Fold changes are shown without significance tests |
| Soil properties, pots | At 2.7 g/kg, pH 7.81 against 8.06 and organic matter 1.96 against 1.87 percent (P < 0.05); available nitrogen and CEC higher at 8.1 g/kg only; available phosphorus unchanged | Small shifts, mostly at the highest rate |
| Seed germination, 7 days | Highest at 80 mg/L, 12.9 percent above control averaged across cultivars; vigour higher at 80 mg/L in Huangmeiren only; no rise over control in Zizhenzhu | Cultivar-dependent; the averaged rise is not separated from control in either cultivar |
| Hydroponic growth, 21 days | Root length 44.4 percent above control at 80 mg/L, also higher at 160 mg/L; biomass 40.8 percent and leaf C/N 14.5 percent above control at 160 mg/L (P < 0.05); 320 and 640 mg/L not different from control | Rises and then falls with concentration |
| Hydroponic leaf minerals | Iron higher at 80 mg/L only; phosphorus, calcium, magnesium, manganese and zinc did not differ from control; potassium lower at 20, 40 and 640 mg/L | A single-concentration iron rise, measured as concentration |
Significance follows the paper's letter groupings (Duncan's multiple range test, P < 0.05). Yield, germination and hydroponic growth were read from the published figures; minerals, dry matter and soil from the published tables. Values are extracted from the source as reported; no raw data were available.
Interpretation and limits
What this record supports
Higher fruit yield at one base-dressing rate, 2.7 g/kg, of this straw-derived fulvic acid in greenhouse pot tomatoes, and longer roots and more biomass at 80 to 160 mg/L in short hydroponic culture.
What remains uncertain
- Dose. Only one of four soil rates raised yield, and the highest rate did not; the dose window was not tested in another soil or season.
- Nutrients. The material contains 5.63 percent nitrogen, potassium, calcium and iron, and controls received no matching nutrients, so a nutrient effect is not separated from a fulvic acid effect.
- Uptake. Fruit and leaf minerals are concentrations; total uptake was not calculated, and several mineral rises stated in the text are not supported by the paper's own significance letters. The text's iron and magnesium percentages do not match its tables.
- Mechanism. The root-growth explanation comes from a separate 21-day hydroponic experiment in another cultivar; root mass did not rise in the pot trial.
- Setting. Pots of one alkaline, phosphorus-rich soil for one season; no field trial.
Which part of the framework it informs
Environmental conditions
The physical, chemical and management context.
Microbial activity
What microbial communities do within that context.
Observable function
What can be observed or measured in the host or wider system.
This record informs this area.
Source, funding and review
- Source type
- Peer-reviewed publication
- Associated products
- This record does not assess an associated product.
- Funding and relationships
- Supported by the National Key R&D Program of China (2018YFD1100103) and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA23020401). The producer of the material, the COFCO Nutrition and Health Research Institute, provided joint funding and supplied it, and three of the eight authors are affiliated with it; the methods call it ‘our product’. The authors declare no commercial or financial conflict of interest.
- Review status
- Prepared as an editorial summary. External scientific review has not been completed.
- What was read
- Full text read through Europe PMC (PMC8542715), with Figures 1, 3 and 4 read from the published images. The supplementary material, including a pak choi experiment and a cost analysis, was not read.
- Original title
- Dose-Dependent Application of Straw-Derived Fulvic Acid on Yield and Quality of Tomato Plants Grown in a Greenhouse
- Authors
- Zhang P, Zhang H, Wu G, Chen X, Gruda N, Li X, Dong J, Duan Z
- Publication
- Frontiers in Plant Science 12:736613, 11 October 2021
- DOI
- 10.3389/fpls.2021.736613
- Summary prepared by
- Carbon Biome Project
- Date added
- 19 October 2026
- Cite this summary
- Carbon Biome Project. A straw-derived fulvic acid raised greenhouse tomato yield at one soil rate, not at lower or higher rates. Evidence library record, added 19 October 2026. carbonbiomeproject.com/evidence/zhang-2021-straw-derived-fulvic-acid-tomato-dose/
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