Evidence hub: field research and trial data
Evidence hub: field research and trial data
Key measured reference points
We do not publish a fertiliser-replacement percentage: how much nitrogen a cover contributes depends on how much biomass it actually grows on your site, and applied mineral nitrogen suppresses fixation, so the two interact rather than simply substituting.
Species nitrogen data: what is actually measured
| Species | Annual N measured (kg N/ha/yr) | Share of N from fixation (Ndfa) | Biomass-N stock (kg N/ha) | Biomass (t DM/ha) | Establishment (time to cover) | Shade tolerance |
|---|---|---|---|---|---|---|
| Pueraria javanica (PJ) | Up to 250, accumulated in above-ground biomass over four years in one trial under young rubber in northeast Thailand (Clermont-Dauphin et al. 2016, Agriculture, Ecosystems & Environment 217:79-88). A single-trial reference, not a design value. The same trial found the cover reduced the drought resilience of the young rubber on water-limited ground, and a closing canopy thins the cover. | 85 to 93% (same trial) | Not reported separately | 5 to 10 in pure stands (Tropical Forages) | 60 to 70% cover at about 4 months, 90 to 100% at 8 months (PROSEA 11) | Moderate while the canopy is open; thins as it closes |
| Calopogonium mucunoides (CM) | No verified annual rate | Not established | Not established | 4 to 6 (Tropical Forages) | Covers the soil 3 to 6 months after sowing; dense sward at 4 to 5 months (PROSEA 11) | Moderate; first to be shaded out in a mixture |
| Centrosema pubescens (CP) | No verified annual rate | Not established | Not established | Not established | Dense cover in a pure sward at 4 to 8 months (PROSEA 11) | High: one of the two shade-persistent successors |
| Mucuna bracteata (MB) | No single routine annual rate is asserted, so we publish none | 67 to 84%, 15N isotope dilution under three-year-old oil palm on Jawa Series soil in Malaysia (Cheah, Zaharah & Aminuddin 2010, MPOB Oil Palm Bulletin 60) | Not established | Not established | About 100% cover at 6 months at 680 seedlings/ha on mineral soil (Samedani et al. 2015); 31, 58, 75 and 78% cover at 6, 12, 18 and 24 months at 320 seedlings/ha on peat (MPOB TT No. 501) | High: the shade-tolerant species, used under maturing oil palm |
| Calopogonium caeruleum (CC) | No verified annual rate | No general figure; 28 to 75% in one Papua New Guinea oil palm study (Pipai et al. 2023) | Not established | 3 to 7 in the open; 1 to 1.5 under mature oil palm at about 10% light (Tropical Forages) | Slow; may take up to 20 months to full cover (PROSEA 4) | High: the other shade-persistent successor |
Each figure in the table is given with its method and source. Mucuna bracteata is the shade-tolerant species of the group, which is why it is used under maturing oil palm, while PJ thins as the canopy closes.
Seeding rates
| Species | Pure stand | Component of a mixture |
|---|---|---|
| Pueraria javanica (PJ) | About 4 kg/ha (Tropical Forages) | 5 to 7.5 kg/ha with 1 to 1.5 kg/ha CC (Tropical Forages); 4 kg/ha in the MPOB TT No. 501 mixture |
| Calopogonium mucunoides (CM) | Set on the quotation | Set on the quotation |
| Centrosema pubescens (CP) | 3 to 5 kg/ha broadcast (Tropical Forages) | 3 kg/ha in the MPOB TT No. 501 mixture |
| Calopogonium caeruleum (CC) | No published rate for CC sown alone; set on the quotation | 1 to 1.5 kg/ha with 5 to 7.5 kg/ha PJ (Tropical Forages); 1 kg/ha in the MPOB TT No. 501 mixture |
| Mucuna bracteata (MB) | Nursery-raised and transplanted, never broadcast or quoted in kg/ha. Published plantings: 320 seedlings/ha, two per palm point, raised from about 500 seeds (75 g) (MPOB TT No. 501, on peat), and 680 seedlings/ha at 1.5 m spacing (Samedani et al. 2015, on mineral soil). | |
A published mixture recipe is MPOB TT No. 501 (Information Series 588, June 2012), Table 1 treatment C2: PJ 4 : CP 3 : CC 1, total 8 kg/ha, with 5 g of Rhizobium (RRI strain) inoculant per kg of seed. It is an institutional best-management-practice recommendation from a peat trial rather than a primary field measurement, and MPOB does not state whether the total is per gross hectare or per interrow hectare actually sown. The seeding rate for your site is set on the quotation.
Weed suppression effectiveness
Established legume cover crops reduce weed growth substantially compared with unweeded controls. In a UPM trial in oil palm on mineral soil, weed dry weight across the cover crop treatments together was 97.3 to 99.9% lower, and weed density 94.77 to 99.73% lower, than in unweeded plots, 9 to 24 months after planting (Samedani et al. 2015). Shade from a closed legume cover, including Calopogonium, Mucuna and Pueraria, has also been shown to suppress Imperata cylindrica (MacDicken et al. 1996).
The mechanism is primarily light exclusion: a dense cover crop canopy limits weed seed germination and rhizome regrowth by cutting light penetration to the soil surface. One caveat worth carrying: until the canopy closes, weeds still compete, so weeding has to be budgeted for during establishment.
Soil health improvements
This is the weakest link in the case for cover crops, and we would rather flag it than oversell it. We do not claim measurable improvements in soil chemical or physical properties from cover crops, because the plantation trials we have reviewed do not show them consistently over the periods studied.
The better-supported benefits are nitrogen contribution, weed suppression after canopy closure, and surface protection. Nitrogen fixation by cover crop root nodules is confirmed by 15N isotope dilution studies (Cheah, Zaharah & Aminuddin 2010), and fixation is suppressed where soil nitrate is high (Pipai et al. 2023).
Erosion control on slopes
Established cover crops reduce runoff and soil loss on sloping ground. In one study in young rubber in Côte d'Ivoire, plots with a Pueraria legume cover had 88% less runoff and 98% less soil loss than bare soil, measured on 1 m2 plots over three years (Perron et al. 2024); small plots tend to give large relative reductions. On the published Malaysian evidence, however, slope and frond management dominate: stacking fronds along the contour instead of down the slope cut runoff from 30.8% to 17.9%, and to 10.7% with silt pits (Afandi et al. 2017, Oil Palm Bulletin 75). A cover crop is one contributor alongside terracing, frond stacking and silt pits, not a replacement for them.
SoilBoost EA performance
Nutrient uptake enhancement
SoilBoost EA's humic and fulvic acids are used to support nutrient uptake and root-zone conditions in tropical crops. It is a soil conditioner: it is not a fertiliser substitute and not a disease treatment.
SoilBoost EA is applied by broadcast at 50 to 100 kg/ha or by drench at 10 to 15 kg/ha, alongside the existing fertiliser programme. The rate for your crop is confirmed on the quotation.
Field trial: SoilBoost EA on banana (FPA EUP No. 3227)
A company-commissioned bioefficacy trial under FPA Experimental Use Permit No. 3227 (registrant Kudzu Seeds Trading, Chemiseed's Philippines-based sister company) on tissue-cultured Lacatan banana, run by an FPA-accredited researcher at the PCA-Davao Research Center from November 2018 to February 2019, found that SoilBoost EA improved seedling growth, nutrient uptake and soil quality, with the strongest results when combined with a balanced fertiliser programme. All growth differences were statistically significant (p < 0.01).
Read the full SoilBoost EA banana trial: methods, results table, chart and citation →
References and further reading
Key sources cited on this page: Clermont-Dauphin, C. et al. (2016), Agriculture, Ecosystems & Environment 217:79-88, doi:10.1016/j.agee.2015.11.002; Cheah, S.S., Zaharah, A.R. & Aminuddin, H. (2010), MPOB Oil Palm Bulletin 60:22-27; Pipai, R. et al. (2023), Plant and Soil 491:665-680; MPOB TT No. 501 / Information Series 588 (Hasnol Othman, Farawahida Mohamad Darus & Zulkifli Hashim, June 2012); Samedani, B. et al. (2015), International Journal of Agriculture and Biology 17(2):251-260; Afandi, A.M. et al. (2017), Oil Palm Bulletin 75:1-10; Perron, T. et al. (2024), Science of the Total Environment 913:169335; MacDicken, K.G. et al. (1996), Agroforestry Systems 36:131-149; Tropical Forages (CIAT and ILRI 2020); PROSEA 4 (Forages) and PROSEA 11 (Chen Chin Peng & Aminah 1997); Eroy, M.N. (2019), bioefficacy terminal report, FPA EUP No. 3227, PCA-Davao Research Center (unpublished registration report). Specific data ranges reflect variability across different soil types, climatic conditions, and management practices, and are given with their method and scope attached.
We continuously update our evidence base as new research becomes available. If you are conducting field trials with our products and would like to share your results, please contact our technical team.