Evidence hub: field research and trial data
Evidence hub: field research and trial data
How to read the evidence on this page
| Label | What it means |
|---|---|
| Peer-reviewed field measurement | A number measured in a specific trial and published in a peer-reviewed journal. The species, site and method are named. Peer-reviewed reviews and meta-analyses are labelled as such, because they synthesise other people's trials rather than reporting new field measurements. |
| Institutional reference work | A figure quoted from a standard agronomic reference such as PROSEA (Plant Resources of South-East Asia). These are authoritative compilations, not primary experiments, and they usually give broad ranges across many sites. |
| Our own records or commissioned trial | Something we or our manufacturer have recorded, including trials we commissioned for product registration. Useful, but not peer-reviewed. We say so plainly. |
Three measured findings
Species performance data
The seeding-rate column gives published rates with their source; where no published rate exists for a species sown alone, the rate is set on the quotation for your site. The other columns are drawn from the source named in each cell. Ranges are wide because these species behave very differently across soils, rainfall and canopy shade.
| Species | Published seeding rate | Reported nitrogen contribution | Reported biomass (t DM/ha/yr) | Time to full ground cover | Shade tolerance |
|---|---|---|---|---|---|
| Pueraria javanica (PJ) | About 4 kg/ha sown alone (Tropical Forages) | 85 to 93% of its N derived from the atmosphere (%Ndfa), and up to 250 kg N/ha/yr accumulated in aboveground biomass, measured in a well-established stand in a rubber intercrop in northeast Thailand (Clermont-Dauphin et al. 2016, peer-reviewed). A measured upper reference point from one trial, not a design value; see the note below, including the drought caveat. | 5 to 10 in pure stands (Tropical Forages) | 60 to 70% cover at about 4 months, 90 to 100% at 8 months (PROSEA 11) | Good (PROSEA) |
| Calopogonium mucunoides (CM) | No published rate for CM sown alone; set on the quotation for your site | No verified species-specific nitrogen figure is published. | 4 to 6 under regular cutting every 9 to 12 weeks (Tropical Forages) | Covers the soil 3 to 6 months after sowing, sooner on newly cleared fertile land; dense sward at 4 to 5 months (PROSEA 11) | Poor; top growth, root growth and nodulation all decline sharply in shade (PROSEA) |
| Centrosema pubescens (CP) | 3 to 5 kg/ha broadcast (Tropical Forages) | No verified species-specific nitrogen figure is published. | No figure confirmed for this species yet | Dense cover in a pure sward 4 to 8 months after sowing; slow to establish (PROSEA 11) | High; persists under heavy shade (PROSEA) |
| Mucuna bracteata (MB) | Not broadcast. 320 nursery-raised seedlings/ha, two per palm point, from about 500 seeds (75 g) (MPOB TT No. 501); 680 seedlings/ha in the Samedani et al. 2015 trial | 67 to 84% of its N derived from the atmosphere (%Ndfa), by 15N isotope dilution (Cheah et al. 2010, peer-reviewed). We do not publish a bare kg N/ha/yr design value for MB. | No figure confirmed for this species yet | About 100% at 6 months on mineral soil at 680 seedlings/ha, 1.5 m spacing (Samedani et al. 2015); 31% at 6 months, 58% at 12, 75% at 18 and 78% at 24 on deep peat at 320 seedlings/ha (MPOB TT No. 501) | Moderate; not quantified in the sources cited here |
| Calopogonium caeruleum (CC) | 1 to 1.5 kg/ha sown with 5 to 7.5 kg/ha PJ (Tropical Forages); no published rate for CC sown alone | Not separately quantified in the sources cited here | 3 to 7 in the open; 1 to 1.5 under mature oil palm at about 10% light (Tropical Forages) | Slower than PJ; may take up to 20 months for complete cover (PROSEA 4) | Very high; still productive under mature oil palm (Tropical Forages) |
On the PJ nitrogen figure. Clermont-Dauphin et al. (2016) measured dinitrogen fixation by Pueraria phaseoloides (PJ) in a rubber intercrop on a toposequence in northeast Thailand. The legume derived 85 to 93% of its nitrogen from the atmosphere (%Ndfa) depending on the year, produced about 8 Mg/ha/yr of aboveground biomass accumulating up to 250 kg N/ha/yr, and supplied 39 to 46% of the nitrogen in the rubber leaves. The 250 kg N/ha/yr figure is a measured upper reference point from one well-established stand under favourable conditions, not a design value and not a promise. Published figures vary widely with site, stand age and management, and a thin or young stand fixes far less. Published methods for quantifying legume cover-crop N in oil palm (for example the ureide technique calibrated by Pipai et al. 2023) show that the answer depends strongly on plantation age and soil nitrate. Legume cover contributes nitrogen; adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
Weed suppression
Cover crops versus unweeded vegetation, Malaysian oil palm
Samedani et al. (2015) compared four ground covers (Axonopus compressus, Calopogonium caeruleum + Centrosema pubescens, Mucuna bracteata, and Pueraria javanica + C. pubescens) against a herbicide-weeded control and unweeded natural vegetation in an oil palm plantation.
Across the cover crop treatments together, weed dry weight was 97.3 to 99.9% lower and weed density 94.77 to 99.73% lower than in the unweeded plots, 9 to 24 months after planting (UPM trial, mineral soil, oil palm). Mucuna bracteata, planted at 680 seedlings per hectare, reached about 100% ground cover at 6 months.
A peer-reviewed review of Mucuna cover cropping that deals mostly with Mucuna pruriens (Dissanayaka et al. 2024) reports the same direction of effect on weeds.
On Imperata cylindrica and the shading mechanism. The suppression mechanism is competitive shading: MacDicken et al. (1996) review shade-based control of Imperata cylindrica and describe it as shade-intolerant, with shading reducing carbohydrate storage, rhizome and tuber-bulb production and shoot dry weight, and increasing susceptibility to competition and to herbicides. That review does not state a specific light threshold. Expect suppression, not eradication, and plan a separate strategy for established Imperata stands.
Soil health and nitrogen
Soil organic matter under Mucuna cover
Dissanayaka et al. (2024), a review of Mucuna cover cropping that deals mostly with Mucuna pruriens in coconut systems, report higher soil organic matter under Mucuna cover than without it, on both flat and sloping land. Improvements of this kind build up over years and are generally largest on degraded or sandy soils where organic matter starts low.
Nitrogen fixation, confirmed isotopically
Nitrogen fixation by cover crop root nodules is not inferred here; it has been measured directly. Cheah, Zaharah and Aminuddin (2010) applied 15N-labelled ammonium sulphate under oil palm field conditions and found Mucuna bracteata derived 67 to 84% of its nitrogen from the atmosphere over a 60-day measurement window, depending on the reference plant used, equivalent to 0.26 to 0.31 g N fixed per square metre over those 60 days. The paper does not annualise this to a kg N/ha/yr figure, and neither do we.
Pipai et al. (2023) calibrated the ureide technique for legume cover plants in oil palm and showed that fixation depends strongly on plantation age and soil nitrate, which is the main reason we will not give you a single design number. Legume cover contributes nitrogen; adjust your fertiliser programme only after soil and leaf analysis shows what the cover supplies on your block.
Erosion and soil physical properties
Ground cover on sloping terrain
Legume covers reduce runoff and erosion on sloping plantation land by intercepting rainfall, slowing overland flow and improving soil physical condition. This has been measured directly for Mucuna bracteata across three slope classes in an immature oil palm plantation by Wawan, Dini and Hapsoh (2019), "The effect of legume cover crop Mucuna bracteata on soil physical properties, runoff and erosion in three slopes of immature oil palm plantation" (IOP Conference Series: Earth and Environmental Science 250: 012021).
The trial ran on 2 x 3 m plots with two replicates in a 3-year-old oil palm plantation in Riau, Indonesia, monitored from February to April. In April, erosion averaged 26.44 t/ha without MB against 9.25 t/ha with MB. It is a small, short conference study, so read it as the direction of the effect rather than a design figure. PROSEA gives how quickly each species closes canopy (roughly 3 to 6 months for CM, 4 months to 60 to 70% cover for PJ, 4 to 8 months for CP, and up to 20 months for CC), and cover established sooner means bare soil exposed for less of the wet season.
SoilBoost EA
What SoilBoost EA is
SoilBoost EA is a Leonardite-derived soil conditioner analysing at 0.45 percent sulphur and pH 3.84. It is manufactured exclusively for Chemiseed Sdn. Bhd. and Kudzu Seeds Trading.
It is not a fertiliser and not a substitute for one, and it is not a fungicide or pesticide. It carries no organic certification; of our range, only Hyacinth Plus is BAFS and Control Union certified. SoilBoost EA is designed to be used alongside a balanced fertiliser programme, not instead of it.
Humic substances are generally understood to support root activity and micronutrient availability. That is the general mechanism proposed for humic amendments, not a measured result for SoilBoost EA.
What the humic acid literature says: about humic acid, not about this product
Ma, Cheng and Zhang (2024) published a meta-analysis in Agronomy pooling humic acid fertiliser trials. Across that pooled dataset, humic acid amendment was associated with an average 12% increase in crop yield, 27% increase in nitrogen use efficiency and 17% increase in nitrogen uptake.
Read that carefully. This meta-analysis is about humic acid products as a class. It did not test SoilBoost EA, and these averages should not be read as a performance promise for SoilBoost EA on your crop. The same paper found that effects were largest in regions with annual precipitation above 300 mm and mean annual temperature above 10 °C and in soils of moderate pH (6 < pH ≤ 8) or low total nitrogen, and that effectiveness diminished under alkaline conditions and in soils with high total nitrogen or low organic carbon. Acidic soils below pH 6 sit outside that band.
Field trial: SoilBoost EA on banana (FPA EUP No. 3227)
This is a bioefficacy trial we commissioned for our own Philippine product registration, not an independent study and not peer-reviewed literature. It was run under Fertilizer and Pesticide Authority Experimental Use Permit No. 3227, registered to Kudzu Seeds Trading, by an FPA-accredited researcher at the PCA-Davao Research Center, on tissue-cultured Lacatan banana seedlings, using a randomized complete block design (6 treatments, 3 replications, 12 seedlings per treatment) and certified as following Good Agricultural Practices. The permit and the report are held by us; they are not published in a journal or in a public database, so you cannot look this up independently. We will send the full summary on request.
Growth was measured 3 months after application, on seedlings. This is a seedling growth trial, not a harvested-yield trial. Differences below were reported as statistically significant (p < 0.01).
| Growth measure | Unfertilized control | SoilBoost EA alone | Full fertilizer + SoilBoost EA |
|---|---|---|---|
| Girth size (cm) | 10.5 | 13.6 | 21.5 |
| Plant height (cm) | 57.9 | 86.6 | 131.0 |
| Living fronds (no.) | 9.3 | 10.7 | 12.4 |
| Leaves produced (no.) | 9.1 | 10.8 | 13.1 |
The trial also recorded higher soil organic matter, available phosphorus and exchangeable potassium, a higher soil pH (5.8 against 5.1 in the control), and improved water-holding capacity (88.7% against 80.0%) with slower soil drying. Note the pattern in the table: SoilBoost EA alone did less than full fertiliser plus SoilBoost EA. That is the point: it is a soil conditioner, used alongside a balanced fertiliser programme rather than as a replacement for it. The trial measured growth, nutrition and soil properties on banana seedlings; it does not support any disease or pest claim, and we make none. Verify the contribution on your own block against your own soil and leaf analysis rather than assuming a fixed fertiliser credit.
Sources
Primary peer-reviewed field measurement: specific trials, named sites and methods.
- Cheah, S.S., Zaharah, A.R. & Aminuddin, H. (2010). Biological nitrogen fixation by Mucuna bracteata under oil palm field environments. Oil Palm Bulletin 60: 22-27. MPOB PDF. 15N isotope dilution; 67 to 84% Ndfa.
- Clermont-Dauphin, C., Suvannang, N., Pongwichian, P., Cheylan, V., Hammecker, C. & Harmand, J.-M. (2016). Dinitrogen fixation by the legume cover crop Pueraria phaseoloides and transfer of fixed N to Hevea brasiliensis: impact on tree growth and vulnerability to drought. Agriculture, Ecosystems & Environment 217: 79-88. doi:10.1016/j.agee.2015.11.002. Rubber intercrop on a toposequence, northeast Thailand; 85 to 93% Ndfa, up to 250 kg N/ha/yr in aboveground biomass from about 8 Mg/ha/yr of biomass, 39 to 46% of rubber leaf N derived from the legume, and reduced drought resilience of the young trees on the water-limited part of the slope.
- Samedani, B., Juraimi, A.S., Rafii, M.Y., Sheikh Awadz, S.A., Anwar, M.P. & Anuar, A.R. (2015). Effect of cover crops on weed suppression in oil palm plantation. International Journal of Agriculture and Biology 17(2): 251-260. CABI PDF. UPM trial on mineral soil under oil palm; weed dry weight and density 9 to 24 months after planting, cited for the cover crop treatments together.
- Pipai, R., McNeill, A.M., Unkovich, M., Banabas, M. & Nelson, P.N. (2023). Biological nitrogen fixation by legume cover plants in oil palm plantations: calibration of the ureide technique and effects of plantation age and soil nitrate. Plant and Soil 491: 665-680. doi:10.1007/s11104-023-06147-8; cited for method and for the age and nitrate dependence, not for a headline number.
- MacDicken, K.G., Hairiah, K., Otsamo, A., Duguma, B. & Majid, N.M. (1996). Shade-based control of Imperata cylindrica: tree fallows and cover crops. Agroforestry Systems 36: 131-149. doi:10.1007/BF00142871; cited for the shading mechanism only; it states no light threshold.
- Wawan, Dini, I.R. & Hapsoh (2019). The effect of legume cover crop Mucuna bracteata on soil physical properties, runoff and erosion in three slopes of immature oil palm plantation. IOP Conference Series: Earth and Environmental Science 250: 012021. doi:10.1088/1755-1315/250/1/012021; 2 x 3 m plots, two replicates, Riau, Indonesia, February to April.
Peer-reviewed evidence synthesis: reviews and meta-analyses. These pool other researchers' trials; they are peer-reviewed, but they are not new field measurements.
- Ma, Y., Cheng, X. & Zhang, Y. (2024). The impact of humic acid fertilizers on crop yield and nitrogen use efficiency: a meta-analysis. Agronomy 14(12): 2763. doi:10.3390/agronomy14122763; about humic acid as a class, not about SoilBoost EA.
- Dissanayaka, D.M.N.S., Udumann, S.S., Nuwarapaksha, T.D. & Atapattu, A.J. (2024). Harnessing the potential of Mucuna cover cropping: a comprehensive review of its agronomic and environmental benefits. Circular Agricultural Systems 4: e003. doi:10.48130/cas-0024-0001; a review of the Mucuna genus, mostly M. pruriens, cited for qualitative points only.
Institutional reference works: standard compilations, not primary experiments.
- PROSEA 4: 't Mannetje, L. & Jones, R.M. (eds) (1992). Plant Resources of South-East Asia No. 4: Forages. Pudoc, Wageningen. Calopogonium caeruleum: time to complete cover.
- PROSEA 11: Faridah Hanum, I. & van der Maesen, L.J.G. (eds) (1997). Plant Resources of South-East Asia No. 11: Auxiliary plants. Backhuys, Leiden. Pueraria phaseoloides, Calopogonium mucunoides and Centrosema pubescens: time to ground cover and shade response.
- Tropical Forages: an interactive selection tool (2020). CIAT and ILRI. tropicalforages.info. Species fact sheets for Neustanthus phaseoloides (PJ), Calopogonium mucunoides, Calopogonium caeruleum and Centrosema pubescens: seeding rates and dry matter yields.
- Hasnol Othman, Farawahida Mohamad Darus & Zulkifli Hashim (2012). Best management practices for oil palm cultivation on peat: Mucuna bracteata as ground cover crop. MPOB Information Series 588 / MPOB TT No. 501. Malaysian Palm Oil Board. MPOB PDF. Deep peat, Teluk Intan; 320 seedlings/ha; ground cover at 6, 12, 18 and 24 months.
PROSEA entries are consultable through the Pl@ntUse platform.
Our own records and commissioned trials: not peer-reviewed.
- SoilBoost EA product specification: 0.45% sulphur, pH 3.84. Manufactured exclusively for Chemiseed Sdn. Bhd. and Kudzu Seeds Trading.
- Eroy, M.N. (2019). Bioefficacy terminal report: SoilBoost EA on tissue-cultured Lacatan banana, FPA Experimental Use Permit No. 3227. PCA-Davao Research Center, Ula, Tugbok, Davao City (November 2018 to February 2019), for registrant Kudzu Seeds Trading. Commissioned by us for product registration; unpublished. Summary available on request.
We update this evidence base as new research becomes available. If you are running field trials with our products and would like to share results, please contact our technical team, including results that disagree with what is on this page.