Best cover crop species for oil palm plantations in Southeast Asia
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For oil palm in tropical Southeast Asia, Pueraria javanica (PJ), with a recommended seeding rate of 10 kg/ha sown alone (Chemiseed recommendation, 2026 catalogue), is the standard cover on open and immature ground, with Calopogonium mucunoides as the fast pioneer alongside it. As the canopy closes PJ thins, and Mucuna bracteata, Centrosema pubescens and Calopogonium caeruleum carry the cover forward. Species choice depends on canopy stage, labour availability, and soil condition.
| Species | Recommended Seeding Rate (sown alone) | Annual N measured (kg N/ha/yr) | Share of N from fixation (Ndfa) | Biomass-N stock (kg N/ha) | Shade Tolerance | Establishment |
|---|---|---|---|---|---|---|
| Pueraria javanica (PJ) | 10 kg/ha sown alone (Chemiseed recommendation, 2026 catalogue) | Up to 250, accumulated in above-ground biomass in one trial under young rubber, NE Thailand (Clermont-Dauphin et al. 2016). Not a design value. | 85-93% (same trial) | Not reported separately | Moderate while the canopy is open; thins as it closes | Drilled or in holes |
| Calopogonium mucunoides (CM) | 10 kg/ha sown alone (Chemiseed recommendation, 2026 catalogue) | No verified annual rate | Not established | Not established | Moderate | Drilled or in holes |
| Centrosema pubescens (CP) | 10 kg/ha sown alone (Chemiseed recommendation, 2026 catalogue) | No verified annual rate | Not established | Not established | High: shade-persistent successor | Drilled or in holes |
| Mucuna bracteata (MB) | 1 kg/ha sown alone (Chemiseed recommendation, 2026 catalogue) | No single routine annual rate is asserted | 67-84%, 15N isotope dilution under three-year-old oil palm on Jawa Series soil (Cheah, Zaharah & Aminuddin 2010, Oil Palm Bulletin 60) | Not established | High: this is the shade-tolerant species, used under maturing palm | Drilled or planted in holes, or nursery seedlings; not broadcast |
Seeding rates in the table are our recommendations for one species sown alone (Chemiseed recommendation, 2026 catalogue); for a mixture, the quantity of each species is set on the quotation for your site. The other columns show what the literature actually measures. Where no sound measurement exists, we say so rather than substitute another number.
Pueraria javanica (PJ), the standard cover for open and immature blocks
PJ is the workhorse cover crop for oil palm, sown in drills or in holes. It establishes quickly from seed; recommended seeding rate (sown alone): 10 kg/ha (Chemiseed recommendation, 2026 catalogue). In the one rubber-intercrop trial where it has been measured in detail, the cover accumulated up to 250 kg N/ha/yr in aboveground biomass at 85 to 93% Ndfa (Clermont-Dauphin et al. 2016, Agriculture, Ecosystems & Environment 217:79-88). Treat that as an upper reference point from a single site, not a planning figure. The same trial also found the cover reduced the drought resilience of the young trees on water-limited ground. PJ thins as the canopy closes, so plan a successor.
View PJ ProductMixed stand for a closing canopy
These rates are for one species sown alone. For a mixture, the quantity of each species is set on the quotation for your site. For the record, MPOB's trial on deep peat (MPOB TT No. 501, Information Series 588, June 2012, Table 1 treatment C2) used PJ 4 : CP 3 : CC 1, total 8 kg/ha, with 5 g of Rhizobium (RRI strain) inoculant per kg of seed; MPOB does not state whether the total is per gross hectare or per interrow hectare actually sown.
View CM View CPMucuna bracteata (MB), high biomass and shade-tolerant, sown or nursery-raised
MB is the shade-tolerant species of the group, which is why it is used under maturing oil palm, and it carries the heaviest biomass. Recommended seeding rate: 1 kg/ha sown alone, drilled or planted in holes. MB can also be raised in a nursery and transplanted; in MPOB's trial on deep peat, 320 seedlings/ha, two per palm point, were raised from about 500 seeds (75 g) (MPOB TT No. 501), and on mineral soil Samedani et al. (2015) planted 680 seedlings per hectare. MB is not broadcast. On nitrogen, 15N isotope dilution puts MB at 67 to 84% of its nitrogen drawn from the atmosphere (Cheah, Zaharah & Aminuddin 2010); that is a proportion, and we do not publish an absolute kg N/ha figure for MB because none we can trace is sound.
View MBSoilBoost EA, complement your cover crop
Pair biological cover crops with SoilBoost EA, a humic acid soil conditioner, to support soil condition and nutrient cycling. It is a soil conditioner: it is not a fertiliser substitute and not a disease treatment.
View SoilBoost EAWe do not put a figure on how much fertiliser a cover crop lets you cut, and we would be cautious about anyone who does: the nitrogen a legume contributes depends on how much biomass it actually grew on your site, and applied mineral nitrogen suppresses fixation, so the two interact rather than simply substituting. What is well supported is that legume covers reduce erosion and runoff on exposed ground, suppress weeds during the immature phase, and build organic matter. Species choice should follow canopy stage: PJ and CM on open ground, MB through the maturing phase, CP and CC as the shade-persistent successors.
Will a cover crop compete with oil palm for water during dry season?
It can, and this is worth planning for rather than dismissing. In the northeast Thailand rubber trial that gives us the best PJ nitrogen measurement (Clermont-Dauphin et al. 2016), the legume cover reduced the drought resilience of the young trees on water-limited ground. PJ and CM have shallow fibrous roots that tap the organic-rich surface layer while palm roots extend deeper, so competition is limited in soils with adequate organic matter and rainfall. On sandy or low-rainfall sites, keep the cover managed back from the planting circle and expect to manage it more actively.
Can I overseed cover crops into existing mature palm without replanting?
Yes, but choose for the light level. After weeding, sow the seed in drills or in holes in the bare soil between palm fronds; broadcasting does not guarantee good germination, especially where the soil dries out easily. Under a closed canopy, CP and CC are the shade-persistent species and will do better than PJ, which thins as light falls. MB tolerates shade well but is not broadcast: sow it at 1 kg/ha, drilled or planted in holes, or transplant nursery seedlings. Let the seedlings establish before applying herbicides near them.
Do I need to inoculate seeds with rhizobia?
Southeast Asian plantation soils often carry sufficient native rhizobia for legume nodulation, but MPOB's published mixture specification includes inoculation at 5 g of Rhizobium (RRI strain) per kg of seed, so it is standard practice rather than an optional extra. Inspect roots for nodules once the seedlings are established; inoculation matters most on previously uncropped or heavily disturbed ground.
How long before I see nitrogen benefit?
Nodulation and fixation begin within the first few months of establishment, and the nitrogen becomes available to the system gradually as cover biomass decomposes rather than as a single release. How much arrives depends on how much biomass the cover actually grows on your site, which is why we give measured reference points rather than a per-hectare promise.
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