Mucuna bracteata (MB): cover crop guide for tropical plantations

Mucuna bracteata (MB) is a vigorous, deep-rooting leguminous cover crop used across tropical oil palm and rubber plantations. It fixes nitrogen, forms a dense ground cover that reduces erosion and weeds, and builds soil organic matter through heavy biomass. Unlike smaller legume seeds, MB is established by raising seedlings in a nursery and transplanting them, not by broadcast sowing.

What is Mucuna bracteata?

Mucuna bracteata is a tropical legume grown as a leguminous cover crop (LCC) in plantation systems. It is valued for fast, vigorous growth, deep rooting, drought tolerance, and the ability to form a thick living mulch between young trees. In association with Rhizobium bacteria in its roots, it fixes atmospheric nitrogen and returns nutrients to the soil through leaf litter.

Why plantations use Mucuna bracteata

Nitrogen fixation

15N isotope-dilution studies under oil palm report that MB derives 67 to 84 percent of its nitrogen from biological fixation (Cheah, Zaharah & Aminuddin 2010, MPOB Oil Palm Bulletin 60). That study measured the proportion of nitrogen drawn from the atmosphere, not an absolute quantity per hectare. We used to publish an absolute annual kilograms-per-hectare figure alongside it; we could not trace that figure to a sound primary source, so we have withdrawn it rather than replace it with another number. What the isotope work supports is that a well-established MB cover meets most of its own nitrogen demand from the air, which can reduce reliance on applied nitrogen during the immature phase.

Ground cover and erosion control

MB spreads quickly to cover bare inter-rows, protecting soil from rainfall impact and runoff on slopes. A dense cover lowers soil loss and helps retain moisture during dry spells.

Weed suppression

By shading the ground, an established MB cover limits light to weeds and reduces manual and chemical weeding in inter-rows.

Biomass and soil organic matter

MB produces large amounts of biomass, up to about 28 t/ha dry matter in the open and around 13 t/ha under 60 to 70 percent shade (MPOB). Decomposing litter feeds soil organic matter and soil biology over time.

How to establish Mucuna bracteata

Because MB seed is large and relatively costly, estates establish it through a nursery rather than broadcasting:

1. Prepare the seed. Hard MB seed benefits from scarification, commonly a hot-water soak, to improve and synchronise germination.
2. Raise seedlings. Germinate and grow seedlings in polybags in a nursery until they are ready to transplant.
3. Transplant. Plant out around 320 seedlings per hectare along the inter-rows (MPOB best management practice on peat). This needs roughly 85 to 100 g of seed per hectare. If you have been quoted MB in kilograms per hectare, the quantity is wrong by a factor of roughly forty: ask before you order.
4. Establish early. Set MB out before or alongside young palm or rubber so the cover is in place during the vulnerable immature phase.

Where Mucuna bracteata fits, and where it does not

Well suited to: immature and young oil palm and rubber, sloping sites that need erosion control, and blocks where rapid ground cover plus a nitrogen contribution are priorities. MB is the shade-tolerant species among the plantation legume covers, which is why it is used under maturing oil palm: MPOB still records around 13 t/ha of dry matter under 60 to 70 percent shade. Pueraria javanica, by contrast, thins as the canopy closes.

Less suitable for: very dry sites without attention to establishment, and the deepest, fully closed canopies, where biomass does eventually fall away. For long-term cover under a closed canopy, Centrosema pubescens and Calopogonium caeruleum are the shade-persistent successors and should be established before closure.

Mucuna bracteata compared with other cover crops

MB typically produces more biomass than conventional leguminous cover crop mixtures, but it is established by transplanting rather than broadcast sowing. Smaller-seeded species such as Pueraria javanica, Calopogonium mucunoides, and Centrosema pubescens are broadcast at a few kilograms per hectare and are quicker and cheaper to sow. Many estates combine MB with these species: MPOB TT No. 501 (Information Series 588, June 2012), Table 1 treatment C4, pairs MB with PJ 3 + CP 1 = 4 kg/ha, against the conventional cover of PJ 4 : CP 3 : CC 1, total 8 kg/ha, in treatment C2. Those are institutional best-management-practice rates from a peat trial, not primary field measurements. See the five-species comparison and the best cover crop for oil palm by growth stage guide.

Frequently asked questions

How much Mucuna bracteata seed do you need per hectare?
MB is nursery-raised and transplanted, not broadcast. Plan around 320 seedlings per hectare, which needs roughly 85 to 100 g of seed per hectare via a polybag nursery (MPOB best management practice). A kilogram-per-hectare rate for MB is wrong by a factor of roughly fifty; confusing the two will put your order badly out.

How much nitrogen does MB fix?
15N isotope-dilution studies report that MB derives 67 to 84 percent of its nitrogen from biological fixation (Cheah, Zaharah & Aminuddin 2010, MPOB Oil Palm Bulletin 60). That is a proportion, not a quantity per hectare, and we are not able to give you a defensible absolute figure. We would rather say that than publish one we cannot stand behind.

How much biomass does MB produce?
Up to about 28 t/ha dry matter in the open and around 13 t/ha under 60 to 70 percent shade (MPOB).

Does MB grow under oil palm shade?
Yes. MB is the shade-tolerant species among the plantation legume covers, which is why it is used under maturing oil palm, and MPOB records around 13 t/ha of dry matter under 60 to 70 percent shade. Biomass does decline as the canopy fully closes, at which point Centrosema pubescens and Calopogonium caeruleum are the shade-persistent successors.

How is MB different from Pueraria javanica?
MB produces more biomass, tolerates shade better, and is transplanted from a nursery, while Pueraria javanica is broadcast-seeded at about 4 to 6 kg per hectare as a pure stand and thins as the canopy closes. Many estates use them together.

Related reading

• Mucuna Bracteata (MB): The Complete Plantation Guide
• Mucuna bracteata in Oil Palm: A Field Guide for Distributors and Estate Managers
• Pueraria javanica vs Mucuna bracteata: Which Cover Crop Suits Your Estate?
• Cover Crop Establishment Guide: From Planting to 80% Ground Cover

Sources: MPOB Oil Palm Bulletin 60 (Cheah, Zaharah & Aminuddin 2010), 15N nitrogen fixation in Mucuna bracteata; MPOB TT No. 501 / Information Series 588 (June 2012), Mucuna bracteata as ground cover crop on peat; Tropical Forages database (CSIRO, CIAT, ILRI). Figures are given with method and context; results depend on site, soil, rainfall, and management. Last reviewed August 2026.