Pueraria for Philippine rubber interrows: nitrogen to the trees

Pueraria javanica is the classic interrow cover for rubber: a vigorous nitrogen-fixing legume that blankets the ground between young trees, suppresses weeds,

Kudzu Seeds Agronomy

June 11, 2026 · 3 min read · 772 words

Pueraria for Philippine rubber interrows: nitrogen to the trees

Pueraria javanica is the classic interrow cover for rubber: a vigorous nitrogen-fixing legume that blankets the ground between young trees, suppresses weeds, protects the soil, and moves fixed nitrogen toward the rubber. Research using nitrogen tracing has confirmed that nitrogen fixed by Pueraria transfers to Hevea (rubber) trees rather than staying locked in the cover. For Philippine rubber growers in Zamboanga, Basilan, and beyond, that nitrogen transfer is the reason this cover has been a standard for generations.

A naming note before anything else: Pueraria javanica is a managed tropical legume, not the invasive kudzu (Pueraria montana). They are different plants. The legume we plant in rubber interrows is the well-behaved, agronomically valued cover species used across Southeast Asian plantations.

Does Pueraria really feed nitrogen to rubber trees?

Yes, and it has been measured. Work on nitrogen transfer from Pueraria to Hevea, using isotope tracing, shows that nitrogen fixed by the legume cover moves into the rubber trees. The cover is not just fixing nitrogen for itself; a portion ends up benefiting the crop you are actually growing. For a young rubber stand, that is supplementary nitrogen reaching the trees during the years when establishment matters most.

On the broader figures, Pueraria is a strong fixer: a typical contribution is on the order of around 150 kg N/ha/yr under good conditions, though the exact amount depends on site, soil, and stand. We cite this as a typical level rather than a guaranteed number, because real-world fixation varies.

What else does a Pueraria cover do in rubber?

Beyond nitrogen, the cover does the standard interrow jobs, and does them well because of its vigour:

Smothers weeds across the interrow, cutting herbicide and slashing costs during the immature years.
Protects the soil surface from raindrop impact and runoff, which matters on the sloping rubber land common in Mindanao.
Holds soil moisture by shading the surface through dry spells.
Builds soil organic matter as the cover cycles leaf and stem material back to the ground.

Like any vigorous legume, Pueraria needs to be kept off the young trees. Train and trim the cover so it does not climb the saplings, especially in the first couple of years.

How should I establish Pueraria in rubber interrows?

Establishment is about clean ground, the right seeding rate, and good timing:

Sow onto prepared, reasonably weed-free interrow ground at the start of reliable rains.
For Pueraria sown pure, plan a seeding rate of around 4 to 6 kg/ha; in a mix with other cover legumes, around 2 to 4 kg/ha.
Ensure the right rhizobia are present so nitrogen fixation actually starts; on new ground, appropriate inoculation supports establishment.
Keep the cover trimmed back from the young rubber stems through the vulnerable early years.

In a designed mix, Pueraria pairs well with shade-tolerant legumes that persist as the canopy closes, so the interrow keeps a living nitrogen source through the cycle.

Where does Pueraria fit in Philippine rubber?

It fits the immature and establishing phase of rubber most strongly, when interrows are open, weed pressure is high, and the young trees benefit most from supplementary nitrogen and erosion control. As the canopy closes, plan a transition to shade-tolerant companions so the ground does not go bare. For estates and smallholders alike, Pueraria is the backbone interrow legume for the establishment years.

FAQ

Is Pueraria javanica the same as invasive kudzu?

No. Pueraria javanica is a managed tropical legume, not the invasive kudzu (Pueraria montana). The interrow cover used in rubber and oil palm is the agronomically valued, well-behaved legume species, not the aggressive temperate kudzu that causes problems elsewhere.

How much nitrogen does Pueraria fix, and does it reach the trees?

A typical contribution is around 150 kg N/ha/yr under good conditions, though it varies by site. Isotope-tracing research confirms that fixed nitrogen transfers from Pueraria to the rubber trees, so the cover genuinely supplements the crop, not just itself.

What seeding rate should I use in rubber interrows?

Around 4 to 6 kg/ha sown pure, or about 2 to 4 kg/ha in a mix with other cover legumes. Match the rate to whether Pueraria is the headline cover or one component of a designed blend.

Get a Pueraria interrow plan for your rubber

We can match Pueraria javanica and its companion legumes to your rubber stand, slope, and stage so the cover protects the ground and feeds nitrogen to the trees. To plan a mix and seeding rate, request a quote or message us on WhatsApp at +60 17-237 4058.